diff --git a/Remotion/Core/Reflection.CodeGeneration.TypePipe.PerformanceTests/CachePerformanceTest.cs b/Remotion/Core/Reflection.CodeGeneration.TypePipe.PerformanceTests/CachePerformanceTest.cs
index 57014f6b92..38781e8722 100644
--- a/Remotion/Core/Reflection.CodeGeneration.TypePipe.PerformanceTests/CachePerformanceTest.cs
+++ b/Remotion/Core/Reflection.CodeGeneration.TypePipe.PerformanceTests/CachePerformanceTest.cs
@@ -65,7 +65,7 @@ public void TypePipe ()
                                SafeServiceLocator.Current.GetInstance<ITargetTypeModifier>(),
                                SafeServiceLocator.Current.GetInstance<IConcreteTypeMetadataImporter>()),
                            new DomainObjectParticipant(
-                               SafeServiceLocator.Current.GetInstance<ITypeDefinitionProvider>(),
+                               SafeServiceLocator.Current.GetInstance<IClassDefinitionProvider>(),
                                SafeServiceLocator.Current.GetInstance<IInterceptedPropertyFinder>())
                          };
       var pipelineFactory = new RemotionPipelineFactory();
diff --git a/Remotion/Data/DomainObjects.ObjectBinding.UnitTests/BindableDomainObjectTest.cs b/Remotion/Data/DomainObjects.ObjectBinding.UnitTests/BindableDomainObjectTest.cs
index ac44e6c70d..38e0aabf00 100644
--- a/Remotion/Data/DomainObjects.ObjectBinding.UnitTests/BindableDomainObjectTest.cs
+++ b/Remotion/Data/DomainObjects.ObjectBinding.UnitTests/BindableDomainObjectTest.cs
@@ -145,7 +145,7 @@ public void Reloading ()
     [Test]
     public void ObjectReference ()
     {
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(SampleBindableDomainObject));
+      var classDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(SampleBindableDomainObject));
       var instance = LifetimeService.GetObjectReference(TestableClientTransaction, new ObjectID(classDefinition, Guid.NewGuid()));
 
       var implementation = (BindableDomainObjectImplementation)PrivateInvoke.GetNonPublicField(instance, "_implementation");
@@ -222,7 +222,7 @@ public void UniqueIdentifier ()
     [Test]
     public void BindableDomainObject_IsNotPartOfMapping ()
     {
-      Assert.That(MappingConfiguration.Current.GetTypeDefinitions().Where(o => o.ClassType == typeof(BindableDomainObject)), Is.Empty);
+      Assert.That(MappingConfiguration.Current.GetTypeDefinitions().Where(o => o.Type == typeof(BindableDomainObject)), Is.Empty);
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.ObjectBinding.UnitTests/SerializableStorageSettings.cs b/Remotion/Data/DomainObjects.ObjectBinding.UnitTests/SerializableStorageSettings.cs
index 749ab96801..2f805c7026 100644
--- a/Remotion/Data/DomainObjects.ObjectBinding.UnitTests/SerializableStorageSettings.cs
+++ b/Remotion/Data/DomainObjects.ObjectBinding.UnitTests/SerializableStorageSettings.cs
@@ -46,9 +46,9 @@ public IReadOnlyCollection<StorageProviderDefinition> GetStorageProviderDefiniti
     return _storageSettingsImplementation.GetStorageProviderDefinitions();
   }
 
-  public StorageProviderDefinition GetStorageProviderDefinition (ClassDefinition classDefinition)
+  public StorageProviderDefinition GetStorageProviderDefinition (TypeDefinition typeDefinition)
   {
-    return _storageSettingsImplementation.GetStorageProviderDefinition(classDefinition);
+    return _storageSettingsImplementation.GetStorageProviderDefinition(typeDefinition);
   }
 
   public StorageProviderDefinition GetStorageProviderDefinition (Type storageGroupTypeOrNull)
diff --git a/Remotion/Data/DomainObjects.PerformanceTests/ClassDefinitionTest.cs b/Remotion/Data/DomainObjects.PerformanceTests/ClassDefinitionTest.cs
index 1d8ff8f716..7adda92452 100644
--- a/Remotion/Data/DomainObjects.PerformanceTests/ClassDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.PerformanceTests/ClassDefinitionTest.cs
@@ -40,7 +40,7 @@ public void GetOppositeClassDefinition ()
       var stopwatch = new Stopwatch();
       stopwatch.Start();
       for (int i = 0; i < TestRepititions; i++)
-        found &= endPoints[i % endPoints.Count].GetOppositeEndPointDefinition().ClassDefinition != null;
+        found &= endPoints[i % endPoints.Count].GetOppositeEndPointDefinition().TypeDefinition != null;
       stopwatch.Stop();
 
       Console.WriteLine(found);
@@ -65,7 +65,7 @@ public void GetMandatoryOppositeClassDefinition ()
       var stopwatch = new Stopwatch();
       stopwatch.Start();
       for (int i = 0; i < TestRepititions; i++)
-        found &= endPoints[i % endPoints.Count].GetOppositeEndPointDefinition().ClassDefinition != null;
+        found &= endPoints[i % endPoints.Count].GetOppositeEndPointDefinition().TypeDefinition != null;
       stopwatch.Stop();
 
       Console.WriteLine(found);
diff --git a/Remotion/Data/DomainObjects.Security.UnitTests/TestDomain/StubStorageProvider.cs b/Remotion/Data/DomainObjects.Security.UnitTests/TestDomain/StubStorageProvider.cs
index af0ac4b1ac..5632888efb 100644
--- a/Remotion/Data/DomainObjects.Security.UnitTests/TestDomain/StubStorageProvider.cs
+++ b/Remotion/Data/DomainObjects.Security.UnitTests/TestDomain/StubStorageProvider.cs
@@ -54,7 +54,7 @@ public override IEnumerable<DataContainer> ExecuteCollectionQuery (IQuery query)
 
       var collection = new List<DataContainer>();
       if (query.ID == GetSecurableObjectsQueryID)
-        collection.Add(DataContainer.CreateNew(CreateNewObjectID(MappingConfiguration.Current.GetTypeDefinition(typeof(SecurableObject)))));
+        collection.Add(DataContainer.CreateNew(CreateNewObjectID(MappingConfiguration.Current.GetClassDefinition(typeof(SecurableObject)))));
 
       return collection.ToArray();
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/ClientTransactionTest.cs b/Remotion/Data/DomainObjects.UnitTests/ClientTransactionTest.cs
index 9a67320cc6..c6c914c119 100644
--- a/Remotion/Data/DomainObjects.UnitTests/ClientTransactionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/ClientTransactionTest.cs
@@ -562,10 +562,10 @@ public void IsInvalid ()
     [Test]
     public void NewObject ()
     {
-      var typeDefinition = GetTypeDefinition(typeof(Order));
+      var classDefinition = GetClassDefinition(typeof(Order));
       var constructorParameters = ParamList.Create(_fakeDomainObject1);
       _objectLifetimeAgentMock
-          .Setup(mock => mock.NewObject(typeDefinition, constructorParameters))
+          .Setup(mock => mock.NewObject(classDefinition, constructorParameters))
           .Returns(_fakeDomainObject1)
           .Verifiable();
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/DataManagement/DataContainerTest.cs b/Remotion/Data/DomainObjects.UnitTests/DataManagement/DataContainerTest.cs
index 2cfcf3e78f..ad890cace7 100644
--- a/Remotion/Data/DomainObjects.UnitTests/DataManagement/DataContainerTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/DataManagement/DataContainerTest.cs
@@ -1664,7 +1664,7 @@ public void SetDataFromSubTransaction_SetsChangedFlag_IfChanged_WithPersistentPr
     public void SetDataFromSubTransaction_SetsChangedFlag_IfChanged_WithNonPersistentProperty ()
     {
       var sourceDataContainer = DataContainer.CreateForExisting(
-          new ObjectID(_nonPersistentPropertyOnPersistentDataContainer.ClassDefinition, Guid.NewGuid()),
+          new ObjectID((ClassDefinition)_nonPersistentPropertyOnPersistentDataContainer.TypeDefinition, Guid.NewGuid()),
           null,
           propertyDefinition => propertyDefinition.DefaultValue);
       sourceDataContainer.SetValue(_nonPersistentPropertyOnPersistentDataContainer, 42);
diff --git a/Remotion/Data/DomainObjects.UnitTests/DataManagement/PropertyValueTest.cs b/Remotion/Data/DomainObjects.UnitTests/DataManagement/PropertyValueTest.cs
index aceed80b67..b04e8643af 100644
--- a/Remotion/Data/DomainObjects.UnitTests/DataManagement/PropertyValueTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/DataManagement/PropertyValueTest.cs
@@ -84,13 +84,13 @@ public void AreValuesDifferent_True ()
     [Test]
     public void PropertyValue_WithReferenceType_NotAllowed ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition("ClassName");
-      PropertyDefinition propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition, "test", typeof(List<object>));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition("ClassName");
+      PropertyDefinition propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(typeDefinition, "test", typeof(List<object>));
       Assert.That(
           () => new PropertyValue(propertyDefinition, null),
           Throws.InstanceOf<NotSupportedException>()
               .With.Message.EqualTo(
-                  @"The property 'test' (declared on class 'ClassName') is invalid because its values cannot be copied. "
+                  @"The property 'test' (declared on type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order') is invalid because its values cannot be copied. "
                   + @"Only value types, strings, the Type type, byte arrays, types implementing IStructuralEquatable, and ObjectIDs are currently supported, "
                   + @"but the property's type is 'System.Collections.Generic.List`1[[" + typeof(object).AssemblyQualifiedName + "]]'."));
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RealObjectEndPoints/SynchronizedRealObjectEndPointSyncStateTest.cs b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RealObjectEndPoints/SynchronizedRealObjectEndPointSyncStateTest.cs
index 3486c6905d..06c7b0b38b 100644
--- a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RealObjectEndPoints/SynchronizedRealObjectEndPointSyncStateTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RealObjectEndPoints/SynchronizedRealObjectEndPointSyncStateTest.cs
@@ -303,9 +303,9 @@ public void FlattenedSerializable ()
       Assert.That(result.TransactionEventSink, Is.Not.Null);
     }
 
-    private IRelationEndPointDefinition GetRelationEndPointDefinition (Type classType, string shortPropertyName)
+    private IRelationEndPointDefinition GetRelationEndPointDefinition (Type type, string shortPropertyName)
     {
-      return Configuration.GetTypeDefinition(classType).GetRelationEndPointDefinition(classType.FullName + "." + shortPropertyName);
+      return Configuration.GetTypeDefinition(type).GetRelationEndPointDefinition(type.FullName + "." + shortPropertyName);
     }
 
     private Action<DomainObject> GetOppositeObjectIDSetter (ObjectEndPointSetCommand command)
diff --git a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RealObjectEndPoints/UnsynchronizedRealObjectEndPointSyncStateTest.cs b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RealObjectEndPoints/UnsynchronizedRealObjectEndPointSyncStateTest.cs
index 9c2e7a405c..bb1dea055e 100644
--- a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RealObjectEndPoints/UnsynchronizedRealObjectEndPointSyncStateTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RealObjectEndPoints/UnsynchronizedRealObjectEndPointSyncStateTest.cs
@@ -101,9 +101,9 @@ public void FlattenedSerializable ()
       Assert.That(result, Is.Not.Null);
     }
 
-    private IRelationEndPointDefinition GetRelationEndPointDefinition (Type classType, string shortPropertyName)
+    private IRelationEndPointDefinition GetRelationEndPointDefinition (Type declaringType, string shortPropertyName)
     {
-      return Configuration.GetTypeDefinition(classType).GetRelationEndPointDefinition(classType.FullName + "." + shortPropertyName);
+      return Configuration.GetTypeDefinition(declaringType).GetRelationEndPointDefinition(declaringType.FullName + "." + shortPropertyName);
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RelationEndPointIDTest.cs b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RelationEndPointIDTest.cs
index 35cd526cb5..94135a1962 100644
--- a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RelationEndPointIDTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RelationEndPointIDTest.cs
@@ -94,7 +94,7 @@ public void Create_WithPropertyIdentifier_InvalidPropertyName ()
       Assert.That(
           () => RelationEndPointID.Create(DomainObjectIDs.Order1, "PropertyName"),
           Throws.ArgumentException
-              .With.ArgumentExceptionMessageEqualTo("No relation found for class 'Order' and property 'PropertyName'.", "propertyIdentifier"));
+              .With.ArgumentExceptionMessageEqualTo("No relation found for type 'Remotion.Data.DomainObjects.UnitTests.TestDomain.Order' and property 'PropertyName'.", "propertyIdentifier"));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RelationEndPointObjectMother.cs b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RelationEndPointObjectMother.cs
index 100cfe07f2..206dfc9f85 100644
--- a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RelationEndPointObjectMother.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RelationEndPointObjectMother.cs
@@ -110,7 +110,7 @@ public static RelationEndPointID CreateRelationEndPointID (ObjectID objectID = n
     {
       objectID = objectID ?? new ObjectID(typeof(Order), Guid.NewGuid());
       shortPropertyName = shortPropertyName ?? "OrderItems";
-      return RelationEndPointID.Create(objectID, objectID.ClassDefinition.ClassType, shortPropertyName);
+      return RelationEndPointID.Create(objectID, objectID.ClassDefinition.Type, shortPropertyName);
     }
 
     public static RelationEndPointID CreateAnonymousEndPointID ()
diff --git a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RootRelationEndPointRegistrationAgentTest.cs b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RootRelationEndPointRegistrationAgentTest.cs
index 03eedc4525..f834991985 100644
--- a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RootRelationEndPointRegistrationAgentTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/RootRelationEndPointRegistrationAgentTest.cs
@@ -152,7 +152,7 @@ public void Serialization ()
     private Mock<IRealObjectEndPoint> CreateRealObjectEndPointMock (ObjectID originatingObjectID, string shortPropertyName, ObjectID oppositeObjectID)
     {
       var endPointMock = new Mock<IRealObjectEndPoint>(MockBehavior.Strict);
-      var relationEndPointID = RelationEndPointID.Create(originatingObjectID, originatingObjectID.ClassDefinition.ClassType, shortPropertyName);
+      var relationEndPointID = RelationEndPointID.Create(originatingObjectID, originatingObjectID.ClassDefinition.Type, shortPropertyName);
       endPointMock.Setup(stub => stub.ID).Returns(relationEndPointID);
       endPointMock.Setup(stub => stub.Definition).Returns(relationEndPointID.Definition);
       endPointMock.Setup(stub => stub.OriginalOppositeObjectID).Returns(oppositeObjectID);
diff --git a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/DomainObjectCollectionEndPointCollectionProviderTest.cs b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/DomainObjectCollectionEndPointCollectionProviderTest.cs
index b4d5ef1998..5881ebe31e 100644
--- a/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/DomainObjectCollectionEndPointCollectionProviderTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/DomainObjectCollectionEndPointCollectionProviderTest.cs
@@ -75,7 +75,7 @@ public void GetCollection ()
     [Test]
     public void GetCollection_CollectionWithWrongCtor ()
     {
-      var classDefinition = GetTypeDefinition(typeof(DomainObjectWithCollectionMissingCtor));
+      var classDefinition = GetClassDefinition(typeof(DomainObjectWithCollectionMissingCtor));
       var relationEndPointDefinition = GetEndPointDefinition(typeof(DomainObjectWithCollectionMissingCtor), "OppositeObjects");
       var endPointID = RelationEndPointID.Create(new ObjectID(classDefinition, Guid.NewGuid()), relationEndPointDefinition);
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/Database/TestDomainDBScriptGenerationTest.cs b/Remotion/Data/DomainObjects.UnitTests/Database/TestDomainDBScriptGenerationTest.cs
index 45dd7acc8b..ebfe9557fe 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Database/TestDomainDBScriptGenerationTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Database/TestDomainDBScriptGenerationTest.cs
@@ -70,7 +70,7 @@ private IEnumerable<Script> GenerateScripts ()
 
       var typeDefinitions = MappingConfiguration.Current.GetTypeDefinitions()
           .Where(e => e.StorageEntityDefinition.StorageProviderID is c_testDomainProviderID or TableInheritanceMappingTest.TableInheritanceTestDomainProviderID)
-          .Where(e => !Attribute.IsDefined(e.ClassType, typeof(ExcludeFromTestDomainDBAttribute)));
+          .Where(e => !Attribute.IsDefined(e.Type, typeof(ExcludeFromTestDomainDBAttribute)));
 
       return scriptGenerator.GetScripts(typeDefinitions)
           .Select(e => new Script(e.StorageProviderDefinition, PatchGeneratedScript(e.SetUpScript), PatchGeneratedScript(e.TearDownScript)));
diff --git a/Remotion/Data/DomainObjects.UnitTests/DomainImplementation/LifetimeServiceTest.cs b/Remotion/Data/DomainObjects.UnitTests/DomainImplementation/LifetimeServiceTest.cs
index cdc646695d..db2eba07f6 100644
--- a/Remotion/Data/DomainObjects.UnitTests/DomainImplementation/LifetimeServiceTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/DomainImplementation/LifetimeServiceTest.cs
@@ -35,7 +35,7 @@ public void NewObject_InvalidType ()
       Assert.That(
           () => LifetimeService.NewObject(TestableClientTransaction, typeof(object), ParamList.Empty),
           Throws.InstanceOf<MappingException>()
-              .With.Message.EqualTo("Mapping does not contain class 'System.Object'."));
+              .With.Message.EqualTo("Mapping does not contain type 'System.Object'."));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/DomainObjectTest.cs b/Remotion/Data/DomainObjects.UnitTests/DomainObjectTest.cs
index 4bdfdebfb6..e6ee1e41fc 100644
--- a/Remotion/Data/DomainObjects.UnitTests/DomainObjectTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/DomainObjectTest.cs
@@ -580,7 +580,7 @@ public void TransactionContext ()
 
     private Type GetConcreteType (Type requestedType)
     {
-      var pipeline = ((DomainObjectCreator)GetTypeDefinition(requestedType).InstanceCreator).PipelineRegistry.DefaultPipeline;
+      var pipeline = ((DomainObjectCreator)GetClassDefinition(requestedType).InstanceCreator).PipelineRegistry.DefaultPipeline;
       var type = pipeline.ReflectionService.GetAssembledType(requestedType);
       return type;
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/DomainObjects/PropertyAccessorDataTest.cs b/Remotion/Data/DomainObjects.UnitTests/DomainObjects/PropertyAccessorDataTest.cs
index ef66323159..092431dafd 100644
--- a/Remotion/Data/DomainObjects.UnitTests/DomainObjects/PropertyAccessorDataTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/DomainObjects/PropertyAccessorDataTest.cs
@@ -42,7 +42,7 @@ public void GetPropertyObjects_StringProperty ()
 
       var propertyObjects = PropertyAccessorData.GetPropertyDefinitionObjects(classDefinition, propertyIdentifier);
       Assert.That(propertyObjects.Item1, Is.Not.Null);
-      Assert.That(propertyObjects.Item1.ClassDefinition, Is.SameAs(classDefinition));
+      Assert.That(propertyObjects.Item1.TypeDefinition, Is.SameAs(classDefinition));
       Assert.That(propertyObjects.Item1.PropertyName, Is.EqualTo(propertyIdentifier));
       Assert.That(propertyObjects.Item2, Is.Null);
     }
@@ -55,7 +55,7 @@ public void GetPropertyObjects_CollectionProperty ()
 
       var propertyObjects = PropertyAccessorData.GetPropertyDefinitionObjects(classDefinition, propertyIdentifier);
       Assert.That(propertyObjects.Item2, Is.Not.Null);
-      Assert.That(propertyObjects.Item2.ClassDefinition, Is.SameAs(classDefinition));
+      Assert.That(propertyObjects.Item2.TypeDefinition, Is.SameAs(classDefinition));
       Assert.That(propertyObjects.Item2.PropertyName, Is.EqualTo(propertyIdentifier));
     }
 
@@ -67,7 +67,7 @@ public void GetPropertyObjects_CollectionProperty_BackReference ()
 
       var propertyObjects = PropertyAccessorData.GetPropertyDefinitionObjects(classDefinition, propertyIdentifier);
       Assert.That(propertyObjects.Item2, Is.Not.Null);
-      Assert.That(propertyObjects.Item2.ClassDefinition, Is.SameAs(classDefinition));
+      Assert.That(propertyObjects.Item2.TypeDefinition, Is.SameAs(classDefinition));
       Assert.That(propertyObjects.Item2.PropertyName, Is.EqualTo(propertyIdentifier));
     }
 
@@ -79,7 +79,7 @@ public void GetPropertyObjects_OneOne_VirtualSide ()
 
       var propertyObjects = PropertyAccessorData.GetPropertyDefinitionObjects(classDefinition, propertyIdentifier);
       Assert.That(propertyObjects.Item2, Is.Not.Null);
-      Assert.That(propertyObjects.Item2.ClassDefinition, Is.SameAs(classDefinition));
+      Assert.That(propertyObjects.Item2.TypeDefinition, Is.SameAs(classDefinition));
       Assert.That(propertyObjects.Item2.PropertyName, Is.EqualTo(propertyIdentifier));
     }
 
@@ -91,7 +91,7 @@ public void GetPropertyObjects_OneOne_RealSide ()
 
       var propertyObjects = PropertyAccessorData.GetPropertyDefinitionObjects(classDefinition, propertyIdentifier);
       Assert.That(propertyObjects.Item2, Is.Not.Null);
-      Assert.That(propertyObjects.Item2.ClassDefinition, Is.SameAs(classDefinition));
+      Assert.That(propertyObjects.Item2.TypeDefinition, Is.SameAs(classDefinition));
       Assert.That(propertyObjects.Item2.PropertyName, Is.EqualTo(propertyIdentifier));
     }
 
@@ -122,7 +122,7 @@ public void InstancePropertyObjects_CollectionProperty ()
     {
       PropertyAccessorData accessor = CreateAccessorData(typeof(IndustrialSector), "Companies");
 
-      Assert.That(accessor.ClassDefinition, Is.SameAs(MappingConfiguration.Current.GetTypeDefinition(typeof(IndustrialSector))));
+      Assert.That(accessor.TypeDefinition, Is.SameAs(MappingConfiguration.Current.GetTypeDefinition(typeof(IndustrialSector))));
       Assert.That(accessor.PropertyIdentifier, Is.EqualTo("Remotion.Data.DomainObjects.UnitTests.TestDomain.IndustrialSector.Companies"));
       Assert.That(accessor.PropertyDefinition, Is.Null);
       Assert.That(accessor.RelationEndPointDefinition, Is.Not.Null);
@@ -315,9 +315,9 @@ public void GetHashCode_Equal ()
       Assert.That(data1.GetHashCode(), Is.EqualTo(data2.GetHashCode()));
     }
 
-    private static string GetPropertyIdentifier (ClassDefinition classDefinition, string shortPropertyName)
+    private static string GetPropertyIdentifier (TypeDefinition typeDefinition, string shortPropertyName)
     {
-      return classDefinition.ClassType.FullName + "." + shortPropertyName;
+      return typeDefinition.Type.FullName + "." + shortPropertyName;
     }
 
     private PropertyAccessorData CreateAccessorData (Type type, string shortIdentifier)
diff --git a/Remotion/Data/DomainObjects.UnitTests/Factories/TableInheritanceDomainObjectIDs.cs b/Remotion/Data/DomainObjects.UnitTests/Factories/TableInheritanceDomainObjectIDs.cs
index a05034a3bd..fcdb0fb4e4 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Factories/TableInheritanceDomainObjectIDs.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Factories/TableInheritanceDomainObjectIDs.cs
@@ -119,7 +119,7 @@ public ObjectID Folder1
 
     private ObjectID CreateObjectID (Type classType, Guid id)
     {
-      return new ObjectID(_mappingConfiguration.GetTypeDefinition(classType), id);
+      return new ObjectID(_mappingConfiguration.GetClassDefinition(classType), id);
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/ObjectLifetime/ObjectLifetimeAgentTest.cs b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/ObjectLifetime/ObjectLifetimeAgentTest.cs
index 3956f195de..e40e0e26b2 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/ObjectLifetime/ObjectLifetimeAgentTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/ObjectLifetime/ObjectLifetimeAgentTest.cs
@@ -58,7 +58,7 @@ public class ObjectLifetimeAgentTest : StandardMappingTest
     private DomainObject _domainObject2;
     private DataContainer _dataContainer2;
     private Mock<IDomainObjectCreator> _domainObjectCreatorMock;
-    private ClassDefinition _typeDefinitionWithCreatorMock;
+    private ClassDefinition _classDefinitionWithCreatorMock;
     private ObjectID _objectIDWithCreatorMock;
 
     public override void SetUp ()
@@ -89,12 +89,12 @@ public override void SetUp ()
       _dataContainer2 = DataContainerObjectMother.CreateExisting(_domainObject2);
 
       _domainObjectCreatorMock = new Mock<IDomainObjectCreator>(MockBehavior.Strict);
-      _typeDefinitionWithCreatorMock = ClassDefinitionObjectMother.CreateClassDefinitionWithTable(
+      _classDefinitionWithCreatorMock = ClassDefinitionObjectMother.CreateClassDefinitionWithTable(
           TestDomainStorageProviderDefinition,
           classType: typeof(OrderItem),
           instanceCreator: _domainObjectCreatorMock.Object);
 
-      _objectIDWithCreatorMock = new ObjectID(_typeDefinitionWithCreatorMock, Guid.NewGuid());
+      _objectIDWithCreatorMock = new ObjectID(_classDefinitionWithCreatorMock, Guid.NewGuid());
     }
 
     [Test]
@@ -102,8 +102,8 @@ public void NewObject ()
     {
       var constructorParameters = ParamList.Create("Some Product");
 
-      _eventSinkWithMock.Setup(mock => mock.RaiseNewObjectCreatingEvent(_typeDefinitionWithCreatorMock.ClassType)).Verifiable();
-      _persistenceStrategyMock.Setup(mock => mock.CreateNewObjectID(_typeDefinitionWithCreatorMock)).Returns(_objectID1).Verifiable();
+      _eventSinkWithMock.Setup(mock => mock.RaiseNewObjectCreatingEvent(_classDefinitionWithCreatorMock.Type)).Verifiable();
+      _persistenceStrategyMock.Setup(mock => mock.CreateNewObjectID(_classDefinitionWithCreatorMock)).Returns(_objectID1).Verifiable();
 
       _domainObjectCreatorMock
           .Setup(
@@ -113,7 +113,7 @@ public void NewObject ()
           .Returns(_domainObject1)
           .Verifiable();
 
-      var result = _agent.NewObject(_typeDefinitionWithCreatorMock, constructorParameters);
+      var result = _agent.NewObject(_classDefinitionWithCreatorMock, constructorParameters);
 
       _eventSinkWithMock.Verify();
       _persistenceStrategyMock.Verify();
@@ -143,7 +143,7 @@ public void NewObject_WithSubTransaction ()
           .Returns(_domainObject1)
           .Verifiable();
 
-      agent.NewObject(_typeDefinitionWithCreatorMock, ParamList.Empty);
+      agent.NewObject(_classDefinitionWithCreatorMock, ParamList.Empty);
 
       _domainObjectCreatorMock.Verify();
     }
@@ -151,9 +151,9 @@ public void NewObject_WithSubTransaction ()
     [Test]
     public void NewObject_AbstractClass ()
     {
-      var typeDefinition = GetTypeDefinition(typeof(AbstractClass));
+      var classDefinition = GetClassDefinition(typeof(AbstractClass));
       Assert.That(
-          () => _agent.NewObject(typeDefinition, ParamList.Empty),
+          () => _agent.NewObject(classDefinition, ParamList.Empty),
           Throws.InvalidOperationException.With.Message.EqualTo(
               "Cannot instantiate type 'Remotion.Data.DomainObjects.UnitTests.TestDomain.AbstractClass' because it is abstract. "
               + "For classes with automatic properties, InstantiableAttribute must be used."));
@@ -166,8 +166,8 @@ public void NewObject_CreationException_CausesObjectToBeDeleted ()
 
       var constructorParameters = ParamList.Empty;
 
-      _eventSinkWithMock.Setup(stub => stub.RaiseNewObjectCreatingEvent(_typeDefinitionWithCreatorMock.ClassType));
-      _persistenceStrategyMock.Setup(stub => stub.CreateNewObjectID(_typeDefinitionWithCreatorMock)).Returns(_objectID1);
+      _eventSinkWithMock.Setup(stub => stub.RaiseNewObjectCreatingEvent(_classDefinitionWithCreatorMock.Type));
+      _persistenceStrategyMock.Setup(stub => stub.CreateNewObjectID(_classDefinitionWithCreatorMock)).Returns(_objectID1);
 
       var exception = new Exception("Test");
       _domainObjectCreatorMock
@@ -185,7 +185,7 @@ public void NewObject_CreationException_CausesObjectToBeDeleted ()
       var deleteCommandMock = SetupDeleteExpectations(sequence, _dataManagerMock, _domainObject1);
       _enlistedDomainObjectManagerMock.Setup(mock => mock.DisenlistDomainObject(_domainObject1)).Verifiable();
 
-      Assert.That(() => _agent.NewObject(_typeDefinitionWithCreatorMock, constructorParameters), Throws.Exception.SameAs(exception));
+      Assert.That(() => _agent.NewObject(_classDefinitionWithCreatorMock, constructorParameters), Throws.Exception.SameAs(exception));
 
       _domainObjectCreatorMock.Verify();
       _dataManagerMock.Verify();
@@ -201,8 +201,8 @@ public void NewObject_CreationException_WithExceptionInDelete ()
 
       var constructorParameters = ParamList.Empty;
 
-      _eventSinkWithMock.Setup(stub => stub.RaiseNewObjectCreatingEvent(_typeDefinitionWithCreatorMock.ClassType));
-      _persistenceStrategyMock.Setup(stub => stub.CreateNewObjectID(_typeDefinitionWithCreatorMock)).Returns(_objectID1);
+      _eventSinkWithMock.Setup(stub => stub.RaiseNewObjectCreatingEvent(_classDefinitionWithCreatorMock.Type));
+      _persistenceStrategyMock.Setup(stub => stub.CreateNewObjectID(_classDefinitionWithCreatorMock)).Returns(_objectID1);
 
       var exceptionInCreate = new Exception("Test");
       _domainObjectCreatorMock
@@ -220,7 +220,7 @@ public void NewObject_CreationException_WithExceptionInDelete ()
       var deleteCommandMock = SetupDeleteExpectationsWithException(sequence, _dataManagerMock, _domainObject1, exceptionInDelete);
 
       Assert.That(
-          () => _agent.NewObject(_typeDefinitionWithCreatorMock, constructorParameters),
+          () => _agent.NewObject(_classDefinitionWithCreatorMock, constructorParameters),
           Throws.TypeOf<ObjectCleanupException>()
               .With.Message.EqualTo(
                   "While cleaning up an object of type 'Remotion.Data.DomainObjects.UnitTests.TestDomain.Order' that threw an exception of type "
@@ -244,8 +244,8 @@ public void NewObject_CreationException_WithoutRegisteredObject ()
     {
       var constructorParameters = ParamList.Empty;
 
-      _eventSinkWithMock.Setup(stub => stub.RaiseNewObjectCreatingEvent(_typeDefinitionWithCreatorMock.ClassType));
-      _persistenceStrategyMock.Setup(stub => stub.CreateNewObjectID(_typeDefinitionWithCreatorMock)).Returns(_objectID1);
+      _eventSinkWithMock.Setup(stub => stub.RaiseNewObjectCreatingEvent(_classDefinitionWithCreatorMock.Type));
+      _persistenceStrategyMock.Setup(stub => stub.CreateNewObjectID(_classDefinitionWithCreatorMock)).Returns(_objectID1);
 
       var exception = new Exception("Test");
       // No object is registered before the exception is thrown
@@ -254,7 +254,7 @@ public void NewObject_CreationException_WithoutRegisteredObject ()
           .Throws(exception)
           .Verifiable();
 
-      Assert.That(() => _agent.NewObject(_typeDefinitionWithCreatorMock, constructorParameters), Throws.Exception.SameAs(exception));
+      Assert.That(() => _agent.NewObject(_classDefinitionWithCreatorMock, constructorParameters), Throws.Exception.SameAs(exception));
 
       _domainObjectCreatorMock.Verify();
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/ObjectPersistence/SubPersistenceStrategyTest.cs b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/ObjectPersistence/SubPersistenceStrategyTest.cs
index 80bcb2377d..68fd42f5d1 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/ObjectPersistence/SubPersistenceStrategyTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/ObjectPersistence/SubPersistenceStrategyTest.cs
@@ -74,7 +74,7 @@ public override void SetUp ()
     [Test]
     public void CreateNewObjectID ()
     {
-      var classDefinition = GetTypeDefinition(typeof(Order));
+      var classDefinition = GetClassDefinition(typeof(Order));
       var fakeResult = DomainObjectIDs.Order1;
 
       _parentTransactionContextMock
diff --git a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/DomainObjectCreatorTest.cs b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/DomainObjectCreatorTest.cs
index 7e28687f74..282cae403c 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/DomainObjectCreatorTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/DomainObjectCreatorTest.cs
@@ -52,7 +52,7 @@ public override void SetUp ()
           SafeServiceLocator.Current.GetInstance<ITargetTypeModifier>(),
           SafeServiceLocator.Current.GetInstance<IConcreteTypeMetadataImporter>());
       var restoreParticipant = new DomainObjectParticipant(
-          SafeServiceLocator.Current.GetInstance<ITypeDefinitionProvider>(),
+          SafeServiceLocator.Current.GetInstance<IClassDefinitionProvider>(),
           SafeServiceLocator.Current.GetInstance<IInterceptedPropertyFinder>());
       _pipeline = SafeServiceLocator.Current.GetInstance<IPipelineFactory>().Create("DomainObjectCreatorTest", remixParticipant, restoreParticipant);
       var pipelineRegistry = new DefaultPipelineRegistry(_pipeline);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/DomainObjectParticipantTest.cs b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/DomainObjectParticipantTest.cs
index dc8ba81e88..ebb88b9d1e 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/DomainObjectParticipantTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/DomainObjectParticipantTest.cs
@@ -33,7 +33,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Infrastructure.TypePipe
   [TestFixture]
   public class DomainObjectParticipantTest : StandardMappingTest
   {
-    private Mock<ITypeDefinitionProvider> _typeDefinitionProviderMock;
+    private Mock<IClassDefinitionProvider> _classDefinitionProviderMock;
 
     private DomainObjectParticipant _participant;
     private Mock<IInterceptedPropertyFinder> _interceptedPropertyFinderMock;
@@ -45,10 +45,10 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _typeDefinitionProviderMock = new Mock<ITypeDefinitionProvider>(MockBehavior.Strict);
+      _classDefinitionProviderMock = new Mock<IClassDefinitionProvider>(MockBehavior.Strict);
       _interceptedPropertyFinderMock = new Mock<IInterceptedPropertyFinder>(MockBehavior.Strict);
 
-      _participant = new DomainObjectParticipant(_typeDefinitionProviderMock.Object, _interceptedPropertyFinderMock.Object);
+      _participant = new DomainObjectParticipant(_classDefinitionProviderMock.Object, _interceptedPropertyFinderMock.Object);
 
       _proxyTypeAssemblyContext = ProxyTypeAssemblyContextObjectMother.Create(requestedType: typeof(Order));
       _proxyType = _proxyTypeAssemblyContext.ProxyType;
@@ -67,12 +67,12 @@ public void Participate_UsesDomainObjectTypeToGetInterceptedProperties ()
     {
       var fakeClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
       var fakeInterceptors = new IAccessorInterceptor[0];
-      _typeDefinitionProviderMock.Setup(mock => mock.GetTypeDefinition(_proxyType.BaseType)).Returns(fakeClassDefinition).Verifiable();
+      _classDefinitionProviderMock.Setup(mock => mock.GetClassDefinition(_proxyType.BaseType)).Returns(fakeClassDefinition).Verifiable();
       _interceptedPropertyFinderMock.Setup(mock => mock.GetPropertyInterceptors(fakeClassDefinition, _proxyType.BaseType)).Returns(fakeInterceptors).Verifiable();
 
       _participant.Participate(null, _proxyTypeAssemblyContext);
 
-      _typeDefinitionProviderMock.Verify();
+      _classDefinitionProviderMock.Verify();
       _interceptedPropertyFinderMock.Verify();
     }
 
@@ -115,13 +115,13 @@ public void Participate_NonDomainObject_Nop ()
       _participant.Participate(null, context);
 
       Assert.That(_proxyType.AddedInterfaces, Has.No.Member(typeof(IInterceptedDomainObject)));
-      _typeDefinitionProviderMock.Verify(mock => mock.GetTypeDefinition(It.IsAny<Type>()), Times.Never());
+      _classDefinitionProviderMock.Verify(mock => mock.GetClassDefinition(It.IsAny<Type>()), Times.Never());
     }
 
     [Test]
     public void Participate_UnmappedDomainObject_Nop ()
     {
-      _typeDefinitionProviderMock.Setup(stub => stub.GetTypeDefinition(_proxyTypeAssemblyContext.RequestedType)).Returns((ClassDefinition)null);
+      _classDefinitionProviderMock.Setup(stub => stub.GetClassDefinition(_proxyTypeAssemblyContext.RequestedType)).Returns((ClassDefinition)null);
 
       _participant.Participate(null, _proxyTypeAssemblyContext);
 
@@ -132,7 +132,7 @@ public void Participate_UnmappedDomainObject_Nop ()
     public void Participate_AbstractDomainObject ()
     {
       var abstractClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(isAbstract: true);
-      _typeDefinitionProviderMock.Setup(stub => stub.GetTypeDefinition(_proxyTypeAssemblyContext.RequestedType)).Returns(abstractClassDefinition);
+      _classDefinitionProviderMock.Setup(stub => stub.GetClassDefinition(_proxyTypeAssemblyContext.RequestedType)).Returns(abstractClassDefinition);
 
       _participant.Participate(null, _proxyTypeAssemblyContext);
 
@@ -142,7 +142,7 @@ public void Participate_AbstractDomainObject ()
     [Test]
     public void HandleNonSubclassableType ()
     {
-      _typeDefinitionProviderMock.Setup(stub => stub.GetTypeDefinition(typeof(object))).Returns((ClassDefinition)null);
+      _classDefinitionProviderMock.Setup(stub => stub.GetClassDefinition(typeof(object))).Returns((ClassDefinition)null);
       Assert.That(() => _participant.HandleNonSubclassableType(typeof(object)), Throws.Nothing);
     }
 
@@ -150,7 +150,7 @@ public void HandleNonSubclassableType ()
     public void HandleNonSubclassableType_AbstractDomainObject ()
     {
       var abstractClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(isAbstract: true);
-      _typeDefinitionProviderMock.Setup(stub => stub.GetTypeDefinition(_proxyTypeAssemblyContext.RequestedType)).Returns(abstractClassDefinition);
+      _classDefinitionProviderMock.Setup(stub => stub.GetClassDefinition(_proxyTypeAssemblyContext.RequestedType)).Returns(abstractClassDefinition);
       Assert.That(() => _participant.HandleNonSubclassableType(_proxyTypeAssemblyContext.RequestedType), Throws.Nothing);
     }
 
@@ -158,7 +158,7 @@ public void HandleNonSubclassableType_AbstractDomainObject ()
     public void HandleNonSubclassableType_UnsubclassableDomainObject ()
     {
       var nonAbstractClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(isAbstract: false);
-      _typeDefinitionProviderMock.Setup(stub => stub.GetTypeDefinition(typeof(NonSubclassableDomainObject))).Returns(nonAbstractClassDefinition);
+      _classDefinitionProviderMock.Setup(stub => stub.GetClassDefinition(typeof(NonSubclassableDomainObject))).Returns(nonAbstractClassDefinition);
       Assert.That(
           () => _participant.HandleNonSubclassableType(typeof(NonSubclassableDomainObject)),
           Throws.InstanceOf<NotSupportedException>()
@@ -171,7 +171,7 @@ public void HandleNonSubclassableType_NonDomainObject_Nop ()
       _participant.HandleNonSubclassableType(typeof(object));
 
       Assert.That(_proxyType.AddedInterfaces, Has.No.Member(typeof(IInterceptedDomainObject)));
-      _typeDefinitionProviderMock.Verify(mock => mock.GetTypeDefinition(It.IsAny<Type>()), Times.Never());
+      _classDefinitionProviderMock.Verify(mock => mock.GetClassDefinition(It.IsAny<Type>()), Times.Never());
     }
 
     [Test]
@@ -191,7 +191,7 @@ public void GetOrCreateAdditionalType ()
     private void StubGetPropertyInterceptors (params IAccessorInterceptor[] accessorInterceptors)
     {
       var fakeClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
-      _typeDefinitionProviderMock.Setup(stub => stub.GetTypeDefinition(It.IsAny<Type>())).Returns(fakeClassDefinition);
+      _classDefinitionProviderMock.Setup(stub => stub.GetClassDefinition(It.IsAny<Type>())).Returns(fakeClassDefinition);
       _interceptedPropertyFinderMock.Setup(stub => stub.GetPropertyInterceptors(It.IsAny<ClassDefinition>(), It.IsAny<Type>())).Returns(accessorInterceptors);
     }
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/ITypeDefinitionProviderTest.cs b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/IClassDefinitionProviderTest.cs
similarity index 80%
rename from Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/ITypeDefinitionProviderTest.cs
rename to Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/IClassDefinitionProviderTest.cs
index a82f3d03d7..074755d19b 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/ITypeDefinitionProviderTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/IClassDefinitionProviderTest.cs
@@ -22,7 +22,7 @@
 namespace Remotion.Data.DomainObjects.UnitTests.Infrastructure.TypePipe
 {
   [TestFixture]
-  public class ITypeDefinitionProviderTest
+  public class IClassDefinitionProviderTest
   {
     private DefaultServiceLocator _serviceLocator;
 
@@ -35,16 +35,16 @@ public void SetUp ()
     [Test]
     public void GetInstance_Once ()
     {
-      var instance = _serviceLocator.GetInstance<ITypeDefinitionProvider>();
+      var instance = _serviceLocator.GetInstance<IClassDefinitionProvider>();
 
-      Assert.That(instance, Is.TypeOf<TypeDefinitionProvider>());
+      Assert.That(instance, Is.TypeOf<ClassDefinitionProvider>());
     }
 
     [Test]
     public void GetInstance_Twice_ReturnsSameInstance ()
     {
-      var instance1 = _serviceLocator.GetInstance<ITypeDefinitionProvider>();
-      var instance2 = _serviceLocator.GetInstance<ITypeDefinitionProvider>();
+      var instance1 = _serviceLocator.GetInstance<IClassDefinitionProvider>();
+      var instance2 = _serviceLocator.GetInstance<IClassDefinitionProvider>();
 
       Assert.That(instance1, Is.SameAs(instance2));
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/InterceptedPropertyCollectorAdapterTest.cs b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/InterceptedPropertyCollectorAdapterTest.cs
index c399bc1be0..6c0ae8ac5f 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/InterceptedPropertyCollectorAdapterTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Infrastructure/TypePipe/InterceptedPropertyCollectorAdapterTest.cs
@@ -41,7 +41,7 @@ public override void SetUp ()
 
       _adapter = new InterceptedPropertyCollectorAdapter();
 
-      _classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(MyDomainObject));
+      _classDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(MyDomainObject));
       _concreteBaseType = typeof(MyConcreteBaseType);
     }
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/NewObject/RecursiveNewObjectCallTest.cs b/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/NewObject/RecursiveNewObjectCallTest.cs
index e6944a6149..b8e852cf7c 100644
--- a/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/NewObject/RecursiveNewObjectCallTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/NewObject/RecursiveNewObjectCallTest.cs
@@ -27,8 +27,8 @@ public void CorrectIDInitialization_WithRecursiveConstruction ()
     {
       var outer = OuterDomainObject.NewObject();
 
-      Assert.That(outer.ID.ClassDefinition.ClassType, Is.SameAs(typeof(OuterDomainObject)));
-      Assert.That(outer.InnerDomainObject.ID.ClassDefinition.ClassType, Is.SameAs(typeof(InnerDomainObject)));
+      Assert.That(outer.ID.ClassDefinition.Type, Is.SameAs(typeof(OuterDomainObject)));
+      Assert.That(outer.InnerDomainObject.ID.ClassDefinition.Type, Is.SameAs(typeof(InnerDomainObject)));
     }
 
     [DBTable]
diff --git a/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/Synchronization/RelationInconcsistenciesTestHelper.cs b/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/Synchronization/RelationInconcsistenciesTestHelper.cs
index 4b4932fabc..ba5e6b8278 100644
--- a/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/Synchronization/RelationInconcsistenciesTestHelper.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/Synchronization/RelationInconcsistenciesTestHelper.cs
@@ -29,7 +29,7 @@ public static ObjectID CreateObjectAndSetRelationInOtherTransaction (RelationEnd
     {
       using (ClientTransaction.CreateRootTransaction().EnterDiscardingScope())
       {
-        var domainObject = LifetimeService.NewObject(ClientTransaction.Current, endPointDefinition.ClassDefinition.ClassType, ParamList.Empty);
+        var domainObject = LifetimeService.NewObject(ClientTransaction.Current, endPointDefinition.TypeDefinition.Type, ParamList.Empty);
         SetForeignKeyProperty(domainObject, endPointDefinition, relatedID);
         ClientTransaction.Current.Commit();
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/Transaction/ClientTransactionExtensionTest.cs b/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/Transaction/ClientTransactionExtensionTest.cs
index af0e1dbb3c..667c517f58 100644
--- a/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/Transaction/ClientTransactionExtensionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/IntegrationTests/Transaction/ClientTransactionExtensionTest.cs
@@ -792,7 +792,7 @@ public void LoadRelatedDataContainerForVirtualEndPoint ()
       //Note: no reading notification must be performed
       using (var persistenceManager = new PersistenceManager(NullPersistenceExtension.Instance, StorageSettings))
       {
-        ClassDefinition orderDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
+        TypeDefinition orderDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
         IRelationEndPointDefinition orderTicketEndPointDefinition =
             orderDefinition.GetRelationEndPointDefinition("Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.OrderTicket");
         persistenceManager.LoadRelatedDataContainer(RelationEndPointID.Create(_order1.ID, orderTicketEndPointDefinition));
diff --git a/Remotion/Data/DomainObjects.UnitTests/Linq/DomainObjectQueryGeneratorTest.cs b/Remotion/Data/DomainObjects.UnitTests/Linq/DomainObjectQueryGeneratorTest.cs
index dbdf62e9f4..7b7a9a9264 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Linq/DomainObjectQueryGeneratorTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Linq/DomainObjectQueryGeneratorTest.cs
@@ -53,7 +53,7 @@ public class DomainObjectQueryGeneratorTest : StandardMappingTest
 
     private DomainObjectQueryGenerator _generator;
 
-    private ClassDefinition _customerClassDefinition;
+    private TypeDefinition _customerTypeDefinition;
     private QueryModel _customerQueryModel;
 
     public override void SetUp ()
@@ -70,7 +70,7 @@ public override void SetUp ()
           _storageTypeInformationProviderStub.Object,
           Configuration);
 
-      _customerClassDefinition = GetTypeDefinition(typeof(Customer));
+      _customerTypeDefinition = GetTypeDefinition(typeof(Customer));
       _customerQueryModel = QueryModelObjectMother.Create(Expression.Constant(null, typeof(Customer)));
     }
 
@@ -550,7 +550,7 @@ public void CreateSequenceQuery_NonEntityQuery ()
       _sqlQueryGeneratorMock.Verify();
       Assert.That(result, Is.TypeOf(typeof(CustomSequenceQueryAdapter<int>)));
       Assert.That(result.ID, Is.EqualTo("id"));
-      Assert.That(result.StorageProviderDefinition, Is.EqualTo(_customerClassDefinition.StorageEntityDefinition.StorageProviderDefinition));
+      Assert.That(result.StorageProviderDefinition, Is.EqualTo(_customerTypeDefinition.StorageEntityDefinition.StorageProviderDefinition));
       Assert.That(result.Statement, Is.EqualTo("SELECT x"));
       Assert.That(result.QueryType, Is.EqualTo(QueryType.Custom));
       Assert.That(result.CollectionType, Is.Null);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Linq/IntegrationTests/FulltextIntegrationTests.cs b/Remotion/Data/DomainObjects.UnitTests/Linq/IntegrationTests/FulltextIntegrationTests.cs
index 37806511ee..455f9244c1 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Linq/IntegrationTests/FulltextIntegrationTests.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Linq/IntegrationTests/FulltextIntegrationTests.cs
@@ -49,10 +49,10 @@ public override void TestFixtureTearDown ()
     [Test]
     public void Fulltext_Spike ()
     {
-      ClassDefinition orderClassDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
+      TypeDefinition orderTypeDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
       var queryDefinition = new QueryDefinition(
           "bla",
-          orderClassDefinition.StorageEntityDefinition.StorageProviderDefinition,
+          orderTypeDefinition.StorageEntityDefinition.StorageProviderDefinition,
           "SELECT * FROM CeoView WHERE Contains ([CeoView].[Name], 'Fischer')",
           QueryType.Collection);
       var query = QueryFactory.CreateQuery(queryDefinition);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Linq/IntegrationTests/IntegrationTestBase.cs b/Remotion/Data/DomainObjects.UnitTests/Linq/IntegrationTests/IntegrationTestBase.cs
index ae99235366..ea1b747a45 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Linq/IntegrationTests/IntegrationTestBase.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Linq/IntegrationTests/IntegrationTestBase.cs
@@ -75,7 +75,7 @@ protected void CheckDataContainersRegistered (params ObjectID[] objectIDs)
     protected void CheckDomainObjectCollectionRelationRegistered (
         ObjectID originatingObjectID, string shortPropertyName, bool checkOrdering, params ObjectID[] expectedRelatedObjectIDs)
     {
-      var declaringType = originatingObjectID.ClassDefinition.ClassType;
+      var declaringType = originatingObjectID.ClassDefinition.Type;
       CheckDomainObjectCollectionRelationRegistered(originatingObjectID, declaringType, shortPropertyName, checkOrdering, expectedRelatedObjectIDs);
     }
 
@@ -99,7 +99,7 @@ protected void CheckDomainObjectCollectionRelationRegistered (
 
     protected void CheckObjectRelationRegistered (ObjectID originatingObjectID, string shortPropertyName, ObjectID expectedRelatedObjectID)
     {
-      var declaringType = originatingObjectID.ClassDefinition.ClassType;
+      var declaringType = originatingObjectID.ClassDefinition.Type;
       CheckObjectRelationRegistered(originatingObjectID, declaringType, shortPropertyName, expectedRelatedObjectID);
     }
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/Linq/StorageSpecificExpressionResolverTest.cs b/Remotion/Data/DomainObjects.UnitTests/Linq/StorageSpecificExpressionResolverTest.cs
index 023ef387e0..fb65d86f84 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Linq/StorageSpecificExpressionResolverTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Linq/StorageSpecificExpressionResolverTest.cs
@@ -39,7 +39,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Linq
   public class StorageSpecificExpressionResolverTest : StandardMappingTest
   {
     private StorageSpecificExpressionResolver _storageSpecificExpressionResolver;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
     private Mock<IRdbmsPersistenceModelProvider> _rdbmsPersistenceModelProviderStub;
     private Mock<IRdbmsStoragePropertyDefinition> _rdbmsStoragePropertyDefinitionStub;
 
@@ -54,8 +54,8 @@ public override void SetUp ()
       _storageSpecificExpressionResolver = new StorageSpecificExpressionResolver(
           _rdbmsPersistenceModelProviderStub.Object);
 
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order));
-      _classDefinition.SetStorageEntity(
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order));
+      _typeDefinition.SetStorageEntity(
           TableDefinitionObjectMother.Create(
               TestDomainStorageProviderDefinition,
               new EntityNameDefinition(null, "Order"),
@@ -80,10 +80,10 @@ public void ResolveEntity ()
           foreignKeyProperty,
           simpleProperty);
       _rdbmsPersistenceModelProviderStub
-          .Setup(stub => stub.GetEntityDefinition(_classDefinition))
+          .Setup(stub => stub.GetEntityDefinition(_typeDefinition))
           .Returns(tableDefinition);
 
-      var result = _storageSpecificExpressionResolver.ResolveEntity(_classDefinition, "o");
+      var result = _storageSpecificExpressionResolver.ResolveEntity(_typeDefinition, "o");
 
       var expectedIdColumn = new SqlColumnDefinitionExpression(typeof(Guid), "o", "ID", true);
       var expectedClassIdColumn = new SqlColumnDefinitionExpression(typeof(string), "o", "ClassID", false);
@@ -173,10 +173,10 @@ public void ResoveIDProperty ()
       var entityDefinition = TableDefinitionObjectMother.Create(TestDomainStorageProviderDefinition, new EntityNameDefinition(null, "Test"));
 
       _rdbmsPersistenceModelProviderStub
-          .Setup(stub => stub.GetEntityDefinition(_classDefinition))
+          .Setup(stub => stub.GetEntityDefinition(_typeDefinition))
           .Returns(entityDefinition);
 
-      var result = _storageSpecificExpressionResolver.ResolveIDProperty(entityExpression, _classDefinition);
+      var result = _storageSpecificExpressionResolver.ResolveIDProperty(entityExpression, _typeDefinition);
 
       var ctor = MemberInfoFromExpressionUtility.GetConstructor(() => new ObjectID("ClassID", "value"));
       SqlExpressionTreeComparer.CheckAreEqualTrees(
@@ -200,13 +200,13 @@ public void ResolveTable_TableDefinitionWithNoSchemaName ()
     {
       var tableDefinition = TableDefinitionObjectMother.Create(
           TestDomainStorageProviderDefinition, new EntityNameDefinition(null, "Table"), new EntityNameDefinition(null, "TableView"));
-      _classDefinition.SetStorageEntity(tableDefinition);
+      _typeDefinition.SetStorageEntity(tableDefinition);
 
       _rdbmsPersistenceModelProviderStub
-          .Setup(stub => stub.GetEntityDefinition(_classDefinition))
-          .Returns(_classDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
+          .Setup(stub => stub.GetEntityDefinition(_typeDefinition))
+          .Returns(_typeDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
 
-      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_classDefinition, "o");
+      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_typeDefinition, "o");
 
       Assert.That(result, Is.Not.Null);
       Assert.That(result.TableName, Is.EqualTo("TableView"));
@@ -219,13 +219,13 @@ public void ResolveTable_TableDefinitionWithSchemaName ()
     {
       var tableDefinition = TableDefinitionObjectMother.Create(
           TestDomainStorageProviderDefinition, new EntityNameDefinition(null, "Table"), new EntityNameDefinition("schemaName", "TableView"));
-      _classDefinition.SetStorageEntity(tableDefinition);
+      _typeDefinition.SetStorageEntity(tableDefinition);
 
       _rdbmsPersistenceModelProviderStub
-          .Setup(stub => stub.GetEntityDefinition(_classDefinition))
-          .Returns(_classDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
+          .Setup(stub => stub.GetEntityDefinition(_typeDefinition))
+          .Returns(_typeDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
 
-      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_classDefinition, "o");
+      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_typeDefinition, "o");
 
       Assert.That(result, Is.Not.Null);
       Assert.That(result.TableName, Is.EqualTo("schemaName.TableView"));
@@ -239,14 +239,14 @@ public void ResolveTable_FilterViewDefinitionWithNoSchemaName ()
       var filterViewDefinition = FilterViewDefinitionObjectMother.Create(
           TestDomainStorageProviderDefinition,
           new EntityNameDefinition(null, "FilterView"),
-          (IRdbmsStorageEntityDefinition)_classDefinition.StorageEntityDefinition);
-      _classDefinition.SetStorageEntity(filterViewDefinition);
+          (IRdbmsStorageEntityDefinition)_typeDefinition.StorageEntityDefinition);
+      _typeDefinition.SetStorageEntity(filterViewDefinition);
 
       _rdbmsPersistenceModelProviderStub
-          .Setup(stub => stub.GetEntityDefinition(_classDefinition))
-          .Returns(_classDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
+          .Setup(stub => stub.GetEntityDefinition(_typeDefinition))
+          .Returns(_typeDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
 
-      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_classDefinition, "o");
+      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_typeDefinition, "o");
 
       Assert.That(result, Is.Not.Null);
       Assert.That(result.TableName, Is.EqualTo("FilterView"));
@@ -260,14 +260,14 @@ public void ResolveTable_FilterViewDefinitionWithSchemaName ()
       var filterViewDefinition = FilterViewDefinitionObjectMother.Create(
           TestDomainStorageProviderDefinition,
           new EntityNameDefinition("schemaName", "FilterView"),
-          (IRdbmsStorageEntityDefinition)_classDefinition.StorageEntityDefinition);
-      _classDefinition.SetStorageEntity(filterViewDefinition);
+          (IRdbmsStorageEntityDefinition)_typeDefinition.StorageEntityDefinition);
+      _typeDefinition.SetStorageEntity(filterViewDefinition);
 
       _rdbmsPersistenceModelProviderStub
-          .Setup(stub => stub.GetEntityDefinition(_classDefinition))
-          .Returns(_classDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
+          .Setup(stub => stub.GetEntityDefinition(_typeDefinition))
+          .Returns(_typeDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
 
-      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_classDefinition, "o");
+      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_typeDefinition, "o");
 
       Assert.That(result, Is.Not.Null);
       Assert.That(result.TableName, Is.EqualTo("schemaName.FilterView"));
@@ -281,14 +281,14 @@ public void ResolveTable_UnionViewDefinitionWithNoSchemaName ()
       var unionViewDefinition = UnionViewDefinitionObjectMother.Create(
           TestDomainStorageProviderDefinition,
           new EntityNameDefinition(null, "UnionView"),
-          new[] { (IRdbmsStorageEntityDefinition)_classDefinition.StorageEntityDefinition });
-      _classDefinition.SetStorageEntity(unionViewDefinition);
+          new[] { (IRdbmsStorageEntityDefinition)_typeDefinition.StorageEntityDefinition });
+      _typeDefinition.SetStorageEntity(unionViewDefinition);
 
       _rdbmsPersistenceModelProviderStub
-          .Setup(stub => stub.GetEntityDefinition(_classDefinition))
-          .Returns(_classDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
+          .Setup(stub => stub.GetEntityDefinition(_typeDefinition))
+          .Returns(_typeDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
 
-      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_classDefinition, "o");
+      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_typeDefinition, "o");
 
       Assert.That(result, Is.Not.Null);
       Assert.That(result.TableName, Is.EqualTo("UnionView"));
@@ -302,14 +302,14 @@ public void ResolveTable_UnionViewDefinitionWithSchemaName ()
       var unionViewDefinition = UnionViewDefinitionObjectMother.Create(
           TestDomainStorageProviderDefinition,
           new EntityNameDefinition("schemaName", "UnionView"),
-          new[] { (IRdbmsStorageEntityDefinition)_classDefinition.StorageEntityDefinition });
-      _classDefinition.SetStorageEntity(unionViewDefinition);
+          new[] { (IRdbmsStorageEntityDefinition)_typeDefinition.StorageEntityDefinition });
+      _typeDefinition.SetStorageEntity(unionViewDefinition);
 
       _rdbmsPersistenceModelProviderStub
-          .Setup(stub => stub.GetEntityDefinition(_classDefinition))
-          .Returns(_classDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
+          .Setup(stub => stub.GetEntityDefinition(_typeDefinition))
+          .Returns(_typeDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
 
-      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_classDefinition, "o");
+      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_typeDefinition, "o");
 
       Assert.That(result, Is.Not.Null);
       Assert.That(result.TableName, Is.EqualTo("schemaName.UnionView"));
@@ -323,13 +323,13 @@ public void ResolveTable_EmptyViewDefinitionWithNoSchemaName ()
       var emptyViewDefinition = EmptyViewDefinitionObjectMother.Create(
           TestDomainStorageProviderDefinition,
           new EntityNameDefinition(null, "EmptyView"));
-      _classDefinition.SetStorageEntity(emptyViewDefinition);
+      _typeDefinition.SetStorageEntity(emptyViewDefinition);
 
       _rdbmsPersistenceModelProviderStub
-          .Setup(stub => stub.GetEntityDefinition(_classDefinition))
-          .Returns(_classDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
+          .Setup(stub => stub.GetEntityDefinition(_typeDefinition))
+          .Returns(_typeDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
 
-      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_classDefinition, "o");
+      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_typeDefinition, "o");
 
       Assert.That(result, Is.Not.Null);
       Assert.That(result.TableName, Is.EqualTo("EmptyView"));
@@ -343,13 +343,13 @@ public void ResolveTable_EmptyViewDefinitionWithSchemaName ()
       var emptyViewDefinition = EmptyViewDefinitionObjectMother.Create(
           TestDomainStorageProviderDefinition,
           new EntityNameDefinition("schemaName", "EmptyView"));
-      _classDefinition.SetStorageEntity(emptyViewDefinition);
+      _typeDefinition.SetStorageEntity(emptyViewDefinition);
 
       _rdbmsPersistenceModelProviderStub
-          .Setup(stub => stub.GetEntityDefinition(_classDefinition))
-          .Returns(_classDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
+          .Setup(stub => stub.GetEntityDefinition(_typeDefinition))
+          .Returns(_typeDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
 
-      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_classDefinition, "o");
+      var result = (ResolvedSimpleTableInfo)_storageSpecificExpressionResolver.ResolveTable(_typeDefinition, "o");
 
       Assert.That(result, Is.Not.Null);
       Assert.That(result.TableName, Is.EqualTo("schemaName.EmptyView"));
@@ -361,7 +361,7 @@ public void ResolveTable_EmptyViewDefinitionWithSchemaName ()
     public void ResolveJoin_LeftSideHoldsForeignKey ()
     {
       // Order.Customer
-      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_classDefinition, "Customer", "Customer");
+      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_typeDefinition, "Customer", "Customer");
 
       var columnDefinition = ColumnDefinitionObjectMother.CreateGuidColumn("Customer");
       _rdbmsStoragePropertyDefinitionStub.Setup(stub => stub.GetColumnsForComparison()).Returns(new[] { columnDefinition });
@@ -373,7 +373,7 @@ public void ResolveJoin_LeftSideHoldsForeignKey ()
           .Returns(_rdbmsStoragePropertyDefinitionStub.Object);
 
       // Customer.Order
-      var customerClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Customer));
+      var customerClassDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Customer));
       var customerTableDefinition = TableDefinitionObjectMother.Create(
           TestDomainStorageProviderDefinition,
           new EntityNameDefinition(null, "CustomerTable"),
@@ -403,16 +403,16 @@ public void ResolveJoin_LeftSideHoldsForeignKey ()
     [Test]
     public void ResolveJoin_LeftSideHoldsNoForeignKey ()
     {
-      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_classDefinition, "Customer", "Customer");
+      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_typeDefinition, "Customer", "Customer");
 
-      var leftEndPointDefinition = new AnonymousRelationEndPointDefinition(_classDefinition);
+      var leftEndPointDefinition = new AnonymousRelationEndPointDefinition(_typeDefinition);
       var rightEndPointDefinition = new RelationEndPointDefinition(propertyDefinition, false);
 
       var entityExpression = CreateEntityDefinition(typeof(Customer), "c");
 
       _rdbmsPersistenceModelProviderStub
-          .Setup(stub => stub.GetEntityDefinition(rightEndPointDefinition.ClassDefinition))
-          .Returns(rightEndPointDefinition.ClassDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
+          .Setup(stub => stub.GetEntityDefinition(rightEndPointDefinition.TypeDefinition))
+          .Returns(rightEndPointDefinition.TypeDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition);
       _rdbmsPersistenceModelProviderStub
           .Setup(stub => stub.GetStoragePropertyDefinition(rightEndPointDefinition.PropertyDefinition))
           .Returns(_rdbmsStoragePropertyDefinitionStub.Object);
@@ -435,7 +435,7 @@ public void ResolveJoin_LeftSideHoldsNoForeignKey ()
     public void ResolveEntityIdentityViaForeignKey ()
     {
       // Order.Customer
-      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_classDefinition, "Customer", "Customer");
+      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_typeDefinition, "Customer", "Customer");
 
       var columnDefinition = ColumnDefinitionObjectMother.CreateStringColumn("Customer");
       _rdbmsStoragePropertyDefinitionStub.Setup(stub => stub.GetColumnsForComparison()).Returns(new[] { columnDefinition });
@@ -457,7 +457,7 @@ public void ResolveEntityIdentityViaForeignKey ()
     [Test]
     public void ResolveIDPropertyViaForeignKey_WithFullObjectID_ResolvesToCompound ()
     {
-      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_classDefinition, "Customer", "Customer");
+      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_typeDefinition, "Customer", "Customer");
       var objectIDStorageProperty = ObjectIDStoragePropertyDefinitionObjectMother.Create(
           "CustomerID",
           "CustomerClassID",
@@ -487,11 +487,11 @@ public void ResolveIDPropertyViaForeignKey_WithFullObjectID_ResolvesToCompound (
     [Test]
     public void ResolveIDPropertyViaForeignKey_WithObjectIDWithoutClassID_ResolvesToCompoundWithFixedConditionalClassID ()
     {
-      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_classDefinition, "Customer", "Customer");
+      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_typeDefinition, "Customer", "Customer");
       var objectIDStorageProperty =
           new ObjectIDWithoutClassIDStoragePropertyDefinition(
               SimpleStoragePropertyDefinitionObjectMother.CreateGuidStorageProperty("CustomerID"),
-              GetTypeDefinition(typeof(Customer)));
+              GetClassDefinition(typeof(Customer)));
 
       var foreignKeyEndPointDefinition = new RelationEndPointDefinition(propertyDefinition, false);
       _rdbmsPersistenceModelProviderStub
@@ -523,7 +523,7 @@ public void ResolveIDPropertyViaForeignKey_WithObjectIDWithoutClassID_ResolvesTo
     [Test]
     public void ResolveIDPropertyViaForeignKey_WithSomeOtherStorageProperty_ReturnsNull ()
     {
-      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_classDefinition, "Customer", "Customer");
+      var propertyDefinition = CreatePropertyDefinitionAndAssociateWithClass(_typeDefinition, "Customer", "Customer");
 
       var foreignKeyEndPointDefinition = new RelationEndPointDefinition(propertyDefinition, false);
       _rdbmsPersistenceModelProviderStub
@@ -537,12 +537,12 @@ public void ResolveIDPropertyViaForeignKey_WithSomeOtherStorageProperty_ReturnsN
       Assert.That(result, Is.Null);
     }
 
-    private PropertyDefinition CreatePropertyDefinition (ClassDefinition classDefinition, string propertyName, string columnName)
+    private PropertyDefinition CreatePropertyDefinition (TypeDefinition typeDefinition, string propertyName, string columnName)
     {
       var propertyInformationStub = new Mock<IPropertyInformation>();
       propertyInformationStub.Setup(_ => _.PropertyType).Returns(typeof(string));
       var propertyDefinition = new PropertyDefinition(
-          classDefinition,
+          typeDefinition,
           propertyInformationStub.Object,
           propertyName,
           true,
@@ -559,10 +559,10 @@ private SqlEntityDefinitionExpression CreateEntityDefinition (Type itemType, str
       return new SqlEntityDefinitionExpression(itemType, tableAlias, null, e => e.GetColumn(typeof(Guid), "ID", true));
     }
 
-    private PropertyDefinition CreatePropertyDefinitionAndAssociateWithClass (ClassDefinition classDefinition, string propertyName, string columnName)
+    private PropertyDefinition CreatePropertyDefinitionAndAssociateWithClass (TypeDefinition typeDefinition, string propertyName, string columnName)
     {
-      var pd = CreatePropertyDefinition(classDefinition, propertyName, columnName);
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { pd }, true));
+      var pd = CreatePropertyDefinition(typeDefinition, propertyName, columnName);
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { pd }, true));
       return pd;
     }
   }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Linq/TestQueryGeneratorMixin.cs b/Remotion/Data/DomainObjects.UnitTests/Linq/TestQueryGeneratorMixin.cs
index 1f35bbb1c9..6d13ea866a 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Linq/TestQueryGeneratorMixin.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Linq/TestQueryGeneratorMixin.cs
@@ -34,7 +34,7 @@ public interface IBaseCallRequirements
     {
       IExecutableQuery<IEnumerable<T>> CreateSequenceQuery<T> (
         string id,
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         QueryModel queryModel,
         IEnumerable<FetchQueryModelBuilder> fetchQueryModelBuilders);
       IExecutableQuery<T> CreateScalarQuery<T> (string id, StorageProviderDefinition storageProviderDefinition, QueryModel queryModel);
@@ -48,12 +48,12 @@ IExecutableQuery<IEnumerable<T>> CreateSequenceQuery<T> (
     [OverrideTarget]
     public IExecutableQuery<IEnumerable<T>> CreateSequenceQuery<T> (
         string id,
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         QueryModel queryModel,
         IEnumerable<FetchQueryModelBuilder> fetchQueryModelBuilders)
     {
       CreateSequenceQueryFromModelCalled = true;
-      return Next.CreateSequenceQuery<T>(id, classDefinition, queryModel, fetchQueryModelBuilders);
+      return Next.CreateSequenceQuery<T>(id, typeDefinition, queryModel, fetchQueryModelBuilders);
     }
 
     [OverrideTarget]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/AnonymousRelationEndPointDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/AnonymousRelationEndPointDefinitionTest.cs
index 8ce32bf01f..47514715b0 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/AnonymousRelationEndPointDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/AnonymousRelationEndPointDefinitionTest.cs
@@ -24,7 +24,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   [TestFixture]
   public class AnonymousRelationEndPointDefinitionTest : MappingReflectionTestBase
   {
-    private ClassDefinition _clientDefinition;
+    private TypeDefinition _clientDefinition;
     private AnonymousRelationEndPointDefinition _definition;
 
     public override void SetUp ()
@@ -39,7 +39,7 @@ public override void SetUp ()
     public void Initialize ()
     {
       Assert.IsInstanceOf<IRelationEndPointDefinition>(_definition);
-      Assert.That(_definition.ClassDefinition, Is.SameAs(_clientDefinition));
+      Assert.That(_definition.TypeDefinition, Is.SameAs(_clientDefinition));
       Assert.That(_definition.Cardinality, Is.EqualTo(CardinalityType.Many));
       Assert.That(_definition.IsMandatory, Is.EqualTo(false));
       Assert.That(_definition.IsVirtual, Is.EqualTo(true));
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionCollectionFactoryTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionCollectionFactoryTest.cs
index 5ceff66bd4..75cd931e2c 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionCollectionFactoryTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionCollectionFactoryTest.cs
@@ -97,10 +97,10 @@ public void CreateClassDefinitionCollection_DerivedClassAreSet ()
 
       Assert.That(classDefinitions.Length, Is.EqualTo(4));
 
-      var orderClassDefinition = classDefinitions.Single(cd => cd.ClassType == typeof(Order));
+      var orderClassDefinition = classDefinitions.Single(cd => cd.Type == typeof(Order));
       Assert.That(orderClassDefinition.DerivedClasses.Count, Is.EqualTo(0));
 
-      var companyClassDefinition = classDefinitions.Single(cd => cd.ClassType == typeof(Company));
+      var companyClassDefinition = classDefinitions.Single(cd => cd.Type == typeof(Company));
       Assert.That(companyClassDefinition.DerivedClasses, Is.EquivalentTo(new[] { fakeClassDefinitionPartner, fakeClassDefinitionCustomer }));
     }
 
@@ -155,7 +155,7 @@ public void GetClassDefinition_ForDerivedClass ()
     public void GetClassDefinition_ForDerivedClass_WithBaseClassAlreadyInClassDefinitionCollection ()
     {
       var expectedBaseClass = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithDifferentProperties));
-      _classDefinitions.Add(expectedBaseClass.ClassType, expectedBaseClass);
+      _classDefinitions.Add(expectedBaseClass.Type, expectedBaseClass);
 
       _mappingObjectFactoryMock
           .Setup(mock => mock.CreateClassDefinition(typeof(DerivedClassWithDifferentProperties), expectedBaseClass))
@@ -174,7 +174,7 @@ public void GetClassDefinition_ForDerivedClass_WithBaseClassAlreadyInClassDefini
     public void GetClassDefinition_ForDerivedClass_WithDerivedClassAlreadyInClassDefinitionCollection ()
     {
       var existing = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(Order));
-      _classDefinitions.Add(existing.ClassType, existing);
+      _classDefinitions.Add(existing.Type, existing);
 
       var actual = _classDefinitionCollectionFactory.GetClassDefinition(_classDefinitions, typeof(Order));
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionObjectMother.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionObjectMother.cs
index 8e399f4245..ed55512857 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionObjectMother.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionObjectMother.cs
@@ -15,6 +15,8 @@
 // along with re-motion; if not, see http://www.gnu.org/licenses.
 // 
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using Moq;
 using Remotion.Data.DomainObjects.Infrastructure;
 using Remotion.Data.DomainObjects.Mapping;
@@ -31,6 +33,7 @@ public static ClassDefinition CreateClassDefinition (
         Type classType = null,
         bool isAbstract = false,
         ClassDefinition baseClass = null,
+        IEnumerable<InterfaceDefinition> implementedInterfaces = null,
         Type storageGroupType = null,
         DefaultStorageClass? defaultStorageClass = null,
         IPersistentMixinFinder persistentMixinFinder = null,
@@ -38,6 +41,7 @@ public static ClassDefinition CreateClassDefinition (
     {
       id = id ?? "Test";
       classType = classType ?? typeof(Order);
+      implementedInterfaces = implementedInterfaces ?? Enumerable.Empty<InterfaceDefinition>();
       var defaultStorageClassNotNullable = defaultStorageClass ?? DefaultStorageClass.Persistent;
       persistentMixinFinder = persistentMixinFinder ?? new PersistentMixinFinderStub(classType, Type.EmptyTypes);
       instanceCreator = instanceCreator ?? new Mock<IDomainObjectCreator>(MockBehavior.Strict).Object;
@@ -47,12 +51,34 @@ public static ClassDefinition CreateClassDefinition (
               classType,
               isAbstract,
               baseClass,
+              implementedInterfaces,
               storageGroupType,
               defaultStorageClassNotNullable,
               persistentMixinFinder,
               instanceCreator);
     }
 
+    public static ClassDefinition CreateClassDefinitionWithDefaultProperties (
+        string id = null,
+        Type classType = null,
+        bool isAbstract = false,
+        ClassDefinition baseClass = null,
+        IEnumerable<InterfaceDefinition> implementedInterfaces = null,
+        Type storageGroupType = null,
+        DefaultStorageClass? defaultStorageClass = null,
+        IPersistentMixinFinder persistentMixinFinder = null,
+        IDomainObjectCreator instanceCreator = null)
+    {
+      var classDefinition = CreateClassDefinition(id, classType, isAbstract, baseClass, implementedInterfaces, storageGroupType, defaultStorageClass, persistentMixinFinder, instanceCreator);
+
+      classDefinition.SetStorageEntity(new FakeStorageEntityDefinition(new UnitTestStorageProviderStubDefinition("stub"), "stub"));
+      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
+      classDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+      classDefinition.SetDerivedClasses(Array.Empty<ClassDefinition>());
+
+      return classDefinition;
+    }
+
     public static ClassDefinition CreateClassDefinition_WithEmptyMembers_AndDerivedClasses (string id = null, Type classType = null, ClassDefinition baseClass = null)
     {
       var classDefinition = CreateClassDefinition(id: id, classType: classType, baseClass: baseClass);
@@ -70,6 +96,7 @@ public static ClassDefinition CreateClassDefinitionWithTable (
         Type classType = null,
         bool isAbstract = false,
         ClassDefinition baseClass = null,
+        IEnumerable<InterfaceDefinition> implementedInterfaces = null,
         Type storageGroupType = null,
         DefaultStorageClass? defaultStorageClass = null,
         IPersistentMixinFinder persistentMixinFinder = null,
@@ -80,6 +107,7 @@ public static ClassDefinition CreateClassDefinitionWithTable (
                 classType,
                 isAbstract,
                 baseClass,
+                implementedInterfaces,
                 storageGroupType,
                 defaultStorageClass,
                 persistentMixinFinder,
@@ -92,5 +120,10 @@ public static ClassDefinition CreateClassDefinitionWithMixins (Type type, params
     {
       return CreateClassDefinition(classType: type, persistentMixinFinder: new PersistentMixinFinderStub(type, mixins));
     }
+
+    public static ClassDefinition CreateClassDefinitionWithMixinsWithDefaultProperties (Type type, params Type[] mixins)
+    {
+      return CreateClassDefinitionWithDefaultProperties(classType: type, persistentMixinFinder: new PersistentMixinFinderStub(type, mixins));
+    }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionTest.cs
index f994bb95a9..370dca9db2 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionTest.cs
@@ -23,14 +23,12 @@
 using Remotion.Data.DomainObjects.Infrastructure;
 using Remotion.Data.DomainObjects.Infrastructure.TypePipe;
 using Remotion.Data.DomainObjects.Mapping;
-using Remotion.Data.DomainObjects.Persistence.Rdbms.Model;
 using Remotion.Data.DomainObjects.UnitTests.Mapping.MixinTestDomain;
 using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration;
 using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.MixedMapping;
 using Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.Model;
 using Remotion.Data.DomainObjects.UnitTests.TestDomain.TableInheritance;
 using Remotion.Development.UnitTesting.Enumerables;
-using Remotion.Development.NUnit.UnitTesting;
 using Remotion.Mixins;
 using Remotion.Reflection;
 
@@ -63,13 +61,13 @@ public override void SetUp ()
 
       _domainBaseClass.SetDerivedClasses(new[] { _personClass, _organizationalUnitClass });
 
-      _orderClass = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
-      _distributorClass = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Distributor)];
+      _orderClass = FakeMappingConfiguration.Current.GetClassDefinition(typeof(Order));
+      _distributorClass = FakeMappingConfiguration.Current.GetClassDefinition(typeof(Distributor));
 
       _targetClassForPersistentMixinClass =
-          FakeMappingConfiguration.Current.TypeDefinitions[typeof(TargetClassForPersistentMixin)];
+          FakeMappingConfiguration.Current.GetClassDefinition(typeof(TargetClassForPersistentMixin));
       _derivedTargetClassForPersistentMixinClass =
-          FakeMappingConfiguration.Current.TypeDefinitions[typeof(DerivedTargetClassForPersistentMixin)];
+          FakeMappingConfiguration.Current.GetClassDefinition(typeof(DerivedTargetClassForPersistentMixin));
     }
 
     [Test]
@@ -83,6 +81,7 @@ public void Initialize ()
               typeof(Order),
               false,
               null,
+              Enumerable.Empty<InterfaceDefinition>(),
               null,
               DefaultStorageClass.Transaction,
               persistentMixinFinder.Object,
@@ -93,9 +92,11 @@ public void Initialize ()
       Assert.That(actual.HasStorageEntityDefinitionBeenSet, Is.False);
       Assert.That(
           () => actual.StorageEntityDefinition,
-          Throws.InvalidOperationException.With.Message.EqualTo("StorageEntityDefinition has not been set for class definition 'Order'."));
-      Assert.That(actual.ClassType, Is.SameAs(typeof(Order)));
+          Throws.InvalidOperationException
+              .With.Message.EqualTo("StorageEntityDefinition has not been set for type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order'."));
+      Assert.That(actual.Type, Is.SameAs(typeof(Order)));
       Assert.That(actual.BaseClass, Is.Null);
+      Assert.That(actual.ImplementedInterfaces, Is.Empty);
       Assert.That(actual.DefaultStorageClass, Is.EqualTo(DefaultStorageClass.Transaction));
       //Assert.That (actual.DerivedClasses.AreResolvedTypesRequired, Is.True);
       Assert.That(actual.IsReadOnly, Is.False);
@@ -114,6 +115,7 @@ public void Initialize_IDCreator_CreatesGenericObjectIDs ()
               typeof(Order),
               false,
               null,
+              Enumerable.Empty<InterfaceDefinition>(),
               null,
               DefaultStorageClass.Persistent,
               persistentMixinFinder.Object,
@@ -140,6 +142,7 @@ public void Initialize_IDCreator_ThrowsWhenNoDomainObject ()
               typeof(string),
               false,
               null,
+              Enumerable.Empty<InterfaceDefinition>(),
               null,
               DefaultStorageClass.Persistent,
               persistentMixinFinder.Object,
@@ -148,15 +151,8 @@ public void Initialize_IDCreator_ThrowsWhenNoDomainObject ()
       Assert.That(classDefinition.HandleCreator, Is.Not.Null);
       Assert.That(
           () => classDefinition.HandleCreator(DomainObjectIDs.Order1),
-          Throws.InvalidOperationException.With.Message.EqualTo("Handles cannot be created when the ClassType does not derive from DomainObject."));
-    }
-
-    [Test]
-    public void InitializeWithNullStorageGroupType ()
-    {
-      ClassDefinition classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(TIDomainBase), storageGroupType: null);
-
-      Assert.That(classDefinition.StorageGroupType, Is.Null);
+          Throws.InvalidOperationException
+              .With.Message.EqualTo("Handles cannot be created when the Type does not derive from DomainObject."));
     }
 
     [Test]
@@ -164,83 +160,9 @@ public void InitializeWithStorageGroupType ()
     {
       ClassDefinition classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(TIDomainBase), storageGroupType: typeof(DBStorageGroupAttribute));
 
-      Assert.That(classDefinition.StorageGroupType, Is.Not.Null);
       Assert.That(classDefinition.StorageGroupType, Is.SameAs(typeof(DBStorageGroupAttribute)));
     }
 
-    [Test]
-    public void SetStorageEntityDefinition ()
-    {
-      var tableDefinition = TableDefinitionObjectMother.Create(_storageProviderDefinition, new EntityNameDefinition(null, "Tablename"));
-      Assert.That(_domainBaseClass.HasStorageEntityDefinitionBeenSet, Is.False);
-
-      _domainBaseClass.SetStorageEntity(tableDefinition);
-
-      Assert.That(_domainBaseClass.StorageEntityDefinition, Is.SameAs(tableDefinition));
-      Assert.That(_domainBaseClass.HasStorageEntityDefinitionBeenSet, Is.True);
-    }
-
-    [Test]
-    public void SetStorageEntityDefinition_ClassIsReadOnly ()
-    {
-      var tableDefinition = TableDefinitionObjectMother.Create(_storageProviderDefinition, new EntityNameDefinition(null, "Tablename"));
-      _domainBaseClass.SetReadOnly();
-
-      Assert.That(
-          () => _domainBaseClass.SetStorageEntity(tableDefinition),
-          Throws.InstanceOf<NotSupportedException>()
-              .With.Message.EqualTo("Class 'DomainBase' is read-only."));
-    }
-
-    [Test]
-    public void SetPropertyDefinitions ()
-    {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_domainBaseClass);
-
-      _domainBaseClass.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, false));
-
-      Assert.That(_domainBaseClass.MyPropertyDefinitions.Count, Is.EqualTo(1));
-      Assert.That(_domainBaseClass.MyPropertyDefinitions[0], Is.SameAs(propertyDefinition));
-      Assert.That(_domainBaseClass.MyPropertyDefinitions.IsReadOnly, Is.True);
-    }
-
-    [Test]
-    public void SetPropertyDefinitions_Twice_ThrowsException ()
-    {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_domainBaseClass);
-
-      _domainBaseClass.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, false));
-      Assert.That(
-          () => _domainBaseClass.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, false)),
-          Throws.InvalidOperationException
-              .With.Message.EqualTo(
-                  "The property-definitions for class 'DomainBase' have already been set."
-));
-    }
-
-    [Test]
-    public void SetPropertyDefinitions_ClassIsReadOnly ()
-    {
-      _domainBaseClass.SetReadOnly();
-      Assert.That(
-          () => _domainBaseClass.SetPropertyDefinitions(new PropertyDefinitionCollection(new PropertyDefinition[0], true)),
-          Throws.InstanceOf<NotSupportedException>()
-              .With.Message.EqualTo("Class 'DomainBase' is read-only."));
-    }
-
-    [Test]
-    public void SetRelationEndPointDefinitions ()
-    {
-      var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _domainBaseClass, "Test", false, new Mock<IPropertyInformation>().Object);
-
-      _domainBaseClass.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPointDefinition }, false));
-
-      Assert.That(_domainBaseClass.MyRelationEndPointDefinitions.Count, Is.EqualTo(1));
-      Assert.That(_domainBaseClass.MyRelationEndPointDefinitions[0], Is.SameAs(endPointDefinition));
-      Assert.That(_domainBaseClass.MyRelationEndPointDefinitions.IsReadOnly, Is.True);
-    }
-
     [Test]
     public void SetRelationEndPointDefinitions_DifferentClassDefinition_ThrowsException ()
     {
@@ -250,7 +172,8 @@ public void SetRelationEndPointDefinitions_DifferentClassDefinition_ThrowsExcept
           () => _domainBaseClass.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPointDefinition }, false)),
           Throws.InstanceOf<MappingException>()
               .With.Message.EqualTo(
-                  "Relation end point for property 'Test' cannot be added to class 'DomainBase', because it was initialized for class 'Distributor'."));
+                  "Relation end point for property 'Test' cannot be added to class 'DomainBase', because it was initialized for class "
+                  + "'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Distributor'."));
     }
 
     [Test]
@@ -270,29 +193,6 @@ public void SetRelationEndPointDefinitions_EndPointWithSamePropertyNameWasAlread
                   + "with the same property name."));
     }
 
-    [Test]
-    public void SetRelationEndPointDefinitions_Twice_ThrowsException ()
-    {
-      var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _domainBaseClass, "Test", false, new Mock<IPropertyInformation>().Object);
-
-      _domainBaseClass.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPointDefinition }, false));
-      Assert.That(
-          () => _domainBaseClass.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPointDefinition }, false)),
-          Throws.InvalidOperationException
-              .With.Message.EqualTo("The relation end point definitions for class 'DomainBase' have already been set."));
-    }
-
-    [Test]
-    public void SetRelationEndPointDefinitions_ClassIsReadonly ()
-    {
-      _domainBaseClass.SetReadOnly();
-      Assert.That(
-          () => _domainBaseClass.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[0], true)),
-          Throws.InstanceOf<NotSupportedException>()
-              .With.Message.EqualTo("Class 'DomainBase' is read-only."));
-    }
-
     [Test]
     public void SetDerivedClasses ()
     {
@@ -302,23 +202,13 @@ public void SetDerivedClasses ()
       Assert.That(_personClass.DerivedClasses[0], Is.SameAs(_customerClass));
     }
 
-    [Test]
-    public void SetDerivedClasses_Twice_ThrowsException ()
-    {
-      _personClass.SetDerivedClasses(new[] { _customerClass });
-      Assert.That(
-          () => _personClass.SetDerivedClasses(new[] { _customerClass }),
-          Throws.InvalidOperationException
-              .With.Message.EqualTo(
-                  "The derived-classes for class 'Person' have already been set."));
-    }
-
     [Test]
     public void SetDerivedClasses_ClasssIsReadOnly ()
     {
-      _personClass.SetReadOnly();
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties("Person");
+      classDefinition.SetReadOnly();
       Assert.That(
-          () => _personClass.SetDerivedClasses(new[] { _orderClass }),
+          () => classDefinition.SetDerivedClasses(new[] { _orderClass }),
           Throws.InstanceOf<NotSupportedException>()
               .With.Message.EqualTo("Class 'Person' is read-only."));
     }
@@ -342,25 +232,12 @@ public void SetDerivedClasses_DerivedClassHasWrongBaseClassDefined ()
                   "Derived class 'Person' cannot be added to class 'Customer', because it has class 'DomainBase' as its base class definition defined."));
     }
 
-    [Test]
-    public void SetReadOnly ()
-    {
-      ClassDefinition actual = ClassDefinitionObjectMother.CreateClassDefinition();
-      actual.SetDerivedClasses(new ClassDefinition[0]);
-      Assert.That(actual.IsReadOnly, Is.False);
-
-      actual.SetReadOnly();
-
-      Assert.That(actual.IsReadOnly, Is.True);
-      Assert.That(((ICollection<ClassDefinition>)actual.DerivedClasses).IsReadOnly, Is.True);
-    }
-
     [Test]
     public void GetToString ()
     {
       ClassDefinition actual = ClassDefinitionObjectMother.CreateClassDefinition("OrderID", typeof(Order));
 
-      Assert.That(actual.ToString(), Is.EqualTo(typeof(ClassDefinition).FullName + ": OrderID"));
+      Assert.That(actual.ToString(), Is.EqualTo(nameof(ClassDefinition) + ": OrderID"));
     }
 
     [Test]
@@ -392,16 +269,6 @@ public void GetRelationEndPointDefinition ()
           Is.Not.Null);
     }
 
-    [Test]
-    public void GetRelationEndPointDefinitionFromEmptyPropertyName ()
-    {
-      Assert.That(
-          () => _orderClass.GetRelationEndPointDefinition(string.Empty),
-          Throws.ArgumentException
-              .With.ArgumentExceptionMessageEqualTo(
-                  "Parameter 'propertyName' cannot be empty.", "propertyName"));
-    }
-
     [Test]
     public void IsRelationEndPointTrue ()
     {
@@ -411,7 +278,7 @@ public void IsRelationEndPointTrue ()
               + "TestDomain.Integration.OrderItem.Order->Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.OrderItems"];
       IRelationEndPointDefinition endPointDefinition =
           orderToOrderItem.GetEndPointDefinition(
-              "Order", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.OrderItems");
+              typeof(Order), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.OrderItems");
 
       Assert.That(_orderClass.IsRelationEndPoint(endPointDefinition), Is.True);
     }
@@ -427,7 +294,7 @@ public void IsRelationEndPointFalse ()
               ];
       IRelationEndPointDefinition partnerEndPoint =
           partnerToPerson.GetEndPointDefinition(
-              "Partner", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Partner.ContactPerson");
+              typeof(Partner), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Partner.ContactPerson");
 
       Assert.That(_orderClass.IsRelationEndPoint(partnerEndPoint), Is.False);
     }
@@ -449,7 +316,7 @@ public void IsRelationEndPointWithInheritance ()
               + "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Partner.ContactPerson->Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Person.AssociatedPartnerCompany"];
       IRelationEndPointDefinition partnerEndPoint =
           partnerToPerson.GetEndPointDefinition(
-              "Partner",
+              typeof(Partner),
               "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Partner.ContactPerson");
 
       Assert.That(_distributorClass.IsRelationEndPoint(partnerEndPoint), Is.True);
@@ -463,26 +330,6 @@ public void GetPropertyDefinition ()
           Is.Not.Null);
     }
 
-    [Test]
-    public void GetPropertyDefinition_NoPropertyDefinitionsHaveBeenSet_ThrowsException ()
-    {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition("Order");
-      Assert.That(
-          () => classDefinition.GetPropertyDefinition("dummy"),
-          Throws.InvalidOperationException
-              .With.Message.EqualTo(
-                  "No property definitions have been set for class 'Order'."));
-    }
-
-    [Test]
-    public void GetEmptyPropertyDefinition ()
-    {
-      Assert.That(
-          () => _orderClass.GetPropertyDefinition(string.Empty),
-          Throws.ArgumentException
-              .With.ArgumentExceptionMessageEqualTo("Parameter 'propertyName' cannot be empty.", "propertyName"));
-    }
-
     [Test]
     public void GetInheritedPropertyDefinition ()
     {
@@ -492,101 +339,87 @@ public void GetInheritedPropertyDefinition ()
     }
 
     [Test]
-    public void GetAllPropertyDefinitions_SucceedsWhenReadOnly ()
+    public void GetPropertyDefinitions_ReadOnly ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
-      classDefinition.SetDerivedClasses(new ClassDefinition[0]);
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new PropertyDefinition[0], true));
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties();
       classDefinition.SetReadOnly();
 
       var result = classDefinition.GetPropertyDefinitions();
 
-      Assert.That(result, Is.Not.Null);
+      Assert.That(result.IsReadOnly, Is.True);
     }
 
     [Test]
-    public void GetAllPropertyDefinitions_ThrowsWhenPropertiesNotSet ()
+    public void SetReadOnly ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition("Order");
-      Assert.That(
-          () => classDefinition.GetPropertyDefinitions(),
-          Throws.InvalidOperationException
-              .With.Message.EqualTo("No property definitions have been set for class 'Order'."));
-    }
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties();
+      Assert.That(classDefinition.IsReadOnly, Is.False);
 
-    [Test]
-    public void GetAllPropertyDefinitions_Cached ()
-    {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition);
-      classDefinition.SetDerivedClasses(new ClassDefinition[0]);
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
       classDefinition.SetReadOnly();
 
-      var result1 = classDefinition.GetPropertyDefinitions();
-      var result2 = classDefinition.GetPropertyDefinitions();
-
-      Assert.That(result1, Is.SameAs(result2));
+      Assert.That(classDefinition.IsReadOnly, Is.True);
     }
 
     [Test]
-    public void GetAllPropertyDefinitions_ReadOnly ()
+    public void SetReadOnly_WithUnsetDerivedClasses_Throws ()
     {
       var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
-      classDefinition.SetDerivedClasses(new ClassDefinition[0]);
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new PropertyDefinition[0], true));
-      classDefinition.SetReadOnly();
-
-      var result = classDefinition.GetPropertyDefinitions();
-
-      Assert.That(result.IsReadOnly, Is.True);
+      Assert.That(
+          () => classDefinition.SetReadOnly(),
+          Throws.InvalidOperationException
+              .With.Message.EqualTo("Cannot set the type definition read-only as the derived classes are not set."));
     }
 
     [Test]
     public void AddPropertyToOtherClass ()
     {
-      var companyClass = ClassDefinitionObjectMother.CreateClassDefinition("Company");
-      var orderClass = ClassDefinitionObjectMother.CreateClassDefinition("Order");
+      var companyClass = ClassDefinitionObjectMother.CreateClassDefinition("Company", typeof(Company));
+      var orderClass = ClassDefinitionObjectMother.CreateClassDefinition("Order", typeof(Order));
 
       var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(companyClass, "Name");
       Assert.That(
           () => orderClass.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true)),
           Throws.InstanceOf<MappingException>()
-              .With.Message.EqualTo("Property 'Name' cannot be added to class 'Order', because it was initialized for class 'Company'."));
+              .With.Message.EqualTo(
+                  "Property 'Name' cannot be added to class 'Order', because it was initialized for "
+                  + "type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Company'."));
     }
 
     [Test]
     public void AddDuplicatePropertyBaseClass ()
     {
-      var companyClass = ClassDefinitionObjectMother.CreateClassDefinition("Company");
+      var companyClass = ClassDefinitionObjectMother.CreateClassDefinition("Company", typeof(Company));
       var companyPropertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(companyClass, "Name");
       companyClass.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { companyPropertyDefinition }, true));
 
-      var customerClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Customer", baseClass: companyClass);
+      var customerClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Customer", classType: typeof(Customer), baseClass: companyClass);
       var customerPropertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(customerClass, "Name");
       Assert.That(
           () => customerClass.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { customerPropertyDefinition }, true)),
           Throws.InstanceOf<MappingException>()
               .With.Message.EqualTo(
-                  "Property 'Name' cannot be added to class 'Customer', because base class 'Company' already defines a property with the same name."));
+                  "Property 'Name' cannot be added to class 'Customer', because base type "
+                  + "'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Company' already defines a property with the same name."));
     }
 
     [Test]
     public void AddDuplicatePropertyBaseOfBaseClass ()
     {
-      var companyClass = ClassDefinitionObjectMother.CreateClassDefinition("Company");
+      var companyClass = ClassDefinitionObjectMother.CreateClassDefinition("Company", typeof(Company));
       var companyPropertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(companyClass, "Name");
       companyClass.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { companyPropertyDefinition }, true));
 
-      var partnerClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Partner", baseClass: companyClass);
+      var partnerClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Partner", typeof(Partner), baseClass: companyClass);
       partnerClass.SetPropertyDefinitions(new PropertyDefinitionCollection());
 
-      var supplierClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Supplier", baseClass: partnerClass);
+      var supplierClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Supplier", typeof(Supplier), baseClass: partnerClass);
       var supplierPropertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(supplierClass, "Name");
       Assert.That(
           () => supplierClass.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { supplierPropertyDefinition }, true)),
           Throws.InstanceOf<MappingException>()
-              .With.Message.EqualTo("Property 'Name' cannot be added to class 'Supplier', because base class 'Company' already defines a property with the same name."));
+              .With.Message.EqualTo(
+                  "Property 'Name' cannot be added to class 'Supplier', because base type "
+                  + "'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Company' already defines a property with the same name."));
     }
 
     [Test]
@@ -596,7 +429,7 @@ public void ConstructorWithoutBaseClass ()
       var instanceCreator = new Mock<IDomainObjectCreator>();
 
       Assert.That(
-          () => new ClassDefinition("id", typeof(Company), false, null, null, DefaultStorageClass.Persistent, persistentMixinFinder.Object, instanceCreator.Object),
+          () => new ClassDefinition("id", typeof(Company), false, null, Enumerable.Empty<InterfaceDefinition>(), null, DefaultStorageClass.Persistent, persistentMixinFinder.Object, instanceCreator.Object),
           Throws.Nothing);
     }
 
@@ -606,54 +439,23 @@ public void GetMandatoryRelationEndPointDefinitionForUndefinedProperty ()
       Assert.That(
           () => _orderClass.GetMandatoryRelationEndPointDefinition("UndefinedProperty"),
           Throws.InstanceOf<MappingException>()
-              .With.Message.EqualTo("No relation found for class 'Order' and property 'UndefinedProperty'."));
+              .With.Message.EqualTo("No relation found for type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order' and property 'UndefinedProperty'."));
     }
 
     [Test]
-    public void GetAllRelationEndPointDefinitions_SucceedsWhenReadOnly ()
-    {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
-      classDefinition.SetDerivedClasses(new ClassDefinition[0]);
-      var endPointDefinition = new VirtualObjectRelationEndPointDefinition(classDefinition, "Test", false, new Mock<IPropertyInformation>().Object);
-      classDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPointDefinition }, true));
-      classDefinition.SetReadOnly();
-
-      var result = classDefinition.GetRelationEndPointDefinitions();
-
-      Assert.That(result, Is.Not.Null);
-    }
-
-    [Test]
-    public void GetAllRelationEndPointDefinitions_ThrowsWhenRelationsNotSet ()
+    public void GetRelationEndPointDefinitions_ThrowsWhenRelationsNotSet ()
     {
       var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition("Order");
       Assert.That(
           () => classDefinition.GetRelationEndPointDefinitions(),
           Throws.InvalidOperationException
-              .With.Message.EqualTo("No relation end point definitions have been set for class 'Order'."));
-    }
-
-    [Test]
-    public void GetAllRelationEndPointDefinitions_Cached ()
-    {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
-      classDefinition.SetDerivedClasses(new ClassDefinition[0]);
-      var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          classDefinition, "Test", false, new Mock<IPropertyInformation>().Object);
-      classDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPointDefinition }, true));
-      classDefinition.SetReadOnly();
-
-      var result1 = classDefinition.GetRelationEndPointDefinitions();
-      var result2 = classDefinition.GetRelationEndPointDefinitions();
-
-      Assert.That(result1, Is.SameAs(result2));
+              .With.Message.EqualTo("No relation end point definitions have been set for type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order'."));
     }
 
     [Test]
-    public void GetAllRelationEndPointDefinitions_ReadOnly ()
+    public void GetRelationEndPointDefinitions_ReadOnly ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
-      classDefinition.SetDerivedClasses(new ClassDefinition[0]);
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties();
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(classDefinition, "Test", false, new Mock<IPropertyInformation>().Object);
       classDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPointDefinition }, true));
       classDefinition.SetReadOnly();
@@ -664,7 +466,7 @@ public void GetAllRelationEndPointDefinitions_ReadOnly ()
     }
 
     [Test]
-    public void GetAllRelationEndPointDefinitions_Content ()
+    public void GetRelationEndPointDefinitions_Content ()
     {
       var relationEndPointDefinitions = _orderClass.GetRelationEndPointDefinitions();
 
@@ -682,7 +484,7 @@ public void GetAllRelationEndPointDefinitions_Content ()
     }
 
     [Test]
-    public void GetAllRelationEndPointDefinitionsWithInheritance ()
+    public void GetRelationEndPointDefinitionsWithInheritance ()
     {
       var relationEndPointDefinitions = _distributorClass.GetRelationEndPointDefinitions();
 
@@ -716,7 +518,7 @@ public void GetDerivedClassesWithoutInheritance ()
     [Test]
     public void GetDerivedClassesWithInheritance ()
     {
-      ClassDefinition companyDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Company));
+      ClassDefinition companyDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Company));
 
       Assert.That(companyDefinition.DerivedClasses, Is.Not.Null);
       Assert.That(companyDefinition.DerivedClasses.Count, Is.EqualTo(2));
@@ -728,7 +530,7 @@ public void GetDerivedClassesWithInheritance ()
     [Test]
     public void IsPartOfInheritanceHierarchy ()
     {
-      ClassDefinition companyDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Company));
+      ClassDefinition companyDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Company));
 
       Assert.That(companyDefinition.IsPartOfInheritanceHierarchy, Is.True);
       Assert.That(_distributorClass.IsPartOfInheritanceHierarchy, Is.True);
@@ -738,9 +540,9 @@ public void IsPartOfInheritanceHierarchy ()
     [Test]
     public void IsRelationEndPointWithAnonymousRelationEndPointDefinition ()
     {
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Client));
+      var classDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Client));
       var relationDefinition = classDefinition.GetRelationEndPointDefinition(typeof(Client).FullName + ".ParentClient").RelationDefinition;
-      var anonymousEndPointDefinition = (AnonymousRelationEndPointDefinition)relationDefinition.GetEndPointDefinition("Client", null);
+      var anonymousEndPointDefinition = (AnonymousRelationEndPointDefinition)relationDefinition.GetEndPointDefinition(typeof(Client), null);
 
       Assert.That(classDefinition.IsRelationEndPoint(anonymousEndPointDefinition), Is.False);
     }
@@ -748,7 +550,7 @@ public void IsRelationEndPointWithAnonymousRelationEndPointDefinition ()
     [Test]
     public void MyPropertyDefinitions ()
     {
-      var clientDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Client));
+      var clientDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Client));
 
       var propertyDefinitions = clientDefinition.MyPropertyDefinitions.ToArray();
 
@@ -765,13 +567,13 @@ public void MyPropertyDefinitions_NoPropertiesSet_ThrowsException ()
       Assert.That(
           () => classDefinition.MyPropertyDefinitions.ForceEnumeration(),
           Throws.InvalidOperationException
-              .With.Message.EqualTo("No property definitions have been set for class 'Order'."));
+              .With.Message.EqualTo("No property definitions have been set for type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order'."));
     }
 
     [Test]
     public void MyRelationEndPointDefinitions ()
     {
-      var clientDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Client));
+      var clientDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Client));
 
       IRelationEndPointDefinition[] endPointDefinitions = clientDefinition.MyRelationEndPointDefinitions.ToArray();
 
@@ -788,13 +590,13 @@ public void MyRelationEndPointDefinitions_NoRelationEndPointDefinitionsSet_Throw
       Assert.That(
           () => classDefinition.MyRelationEndPointDefinitions.ForceEnumeration(),
           Throws.InvalidOperationException
-              .With.Message.EqualTo("No relation end point definitions have been set for class 'Order'."));
+              .With.Message.EqualTo("No relation end point definitions have been set for type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order'."));
     }
 
     [Test]
     public void MyRelationEndPointDefinitionsCompositeBaseClass ()
     {
-      ClassDefinition fileSystemItemDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(FileSystemItem));
+      ClassDefinition fileSystemItemDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(FileSystemItem));
 
       IRelationEndPointDefinition[] endPointDefinitions = fileSystemItemDefinition.MyRelationEndPointDefinitions.ToArray();
 
@@ -807,7 +609,7 @@ public void MyRelationEndPointDefinitionsCompositeBaseClass ()
     [Test]
     public void IsMyRelationEndPoint ()
     {
-      ClassDefinition folderDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Folder));
+      ClassDefinition folderDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Folder));
 
       IRelationEndPointDefinition folderEndPoint =
           folderDefinition.GetRelationEndPointDefinition("Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Folder.FileSystemItems");
@@ -821,7 +623,7 @@ public void IsMyRelationEndPoint ()
     [Test]
     public void MyRelationEndPointDefinitionsCompositeDerivedClass ()
     {
-      ClassDefinition folderDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Folder));
+      ClassDefinition folderDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Folder));
 
       IRelationEndPointDefinition[] endPointDefinitions = folderDefinition.MyRelationEndPointDefinitions.ToArray();
 
@@ -834,7 +636,7 @@ public void MyRelationEndPointDefinitionsCompositeDerivedClass ()
     [Test]
     public void GetRelationEndPointDefinitionsCompositeBaseClass ()
     {
-      ClassDefinition fileSystemItemDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(FileSystemItem));
+      ClassDefinition fileSystemItemDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(FileSystemItem));
 
       var endPointDefinitions = fileSystemItemDefinition.GetRelationEndPointDefinitions();
 
@@ -847,7 +649,7 @@ public void GetRelationEndPointDefinitionsCompositeBaseClass ()
     [Test]
     public void GetRelationEndPointDefinitionsCompositeDerivedClass ()
     {
-      ClassDefinition folderDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Folder));
+      ClassDefinition folderDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Folder));
 
       var endPointDefinitions = folderDefinition.GetRelationEndPointDefinitions();
 
@@ -863,7 +665,7 @@ public void GetRelationEndPointDefinitionsCompositeDerivedClass ()
     [Test]
     public void GetRelationEndPointDefinitionCompositeBaseClass ()
     {
-      ClassDefinition fileSystemItemDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(FileSystemItem));
+      ClassDefinition fileSystemItemDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(FileSystemItem));
 
       Assert.That(
           fileSystemItemDefinition.GetRelationEndPointDefinition("Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.FileSystemItem.ParentFolder"),
@@ -876,7 +678,7 @@ public void GetRelationEndPointDefinitionCompositeBaseClass ()
     [Test]
     public void GetRelationEndPointDefinitionCompositeDerivedClass ()
     {
-      ClassDefinition folderDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Folder));
+      ClassDefinition folderDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Folder));
 
       Assert.That(
           folderDefinition.GetRelationEndPointDefinition("Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.FileSystemItem.ParentFolder"),
@@ -900,7 +702,7 @@ public void GetMandatoryPropertyDefinitionWithInvalidPropertyName ()
       Assert.That(
           () => _orderClass.GetMandatoryPropertyDefinition("InvalidProperty"),
           Throws.InstanceOf<MappingException>()
-              .With.Message.EqualTo("Class 'Order' does not contain the property 'InvalidProperty'."));
+              .With.Message.EqualTo("Type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order' does not contain the property 'InvalidProperty'."));
     }
 
     [Test]
@@ -911,31 +713,44 @@ public void SetClassDefinitionOfPropertyDefinition ()
       var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
 
       PropertyDefinition propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition);
-      Assert.That(propertyDefinition.ClassDefinition, Is.SameAs(classDefinition));
+      Assert.That(propertyDefinition.TypeDefinition, Is.SameAs(classDefinition));
 
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      Assert.That(propertyDefinition.ClassDefinition, Is.SameAs(classDefinition));
+      Assert.That(propertyDefinition.TypeDefinition, Is.SameAs(classDefinition));
     }
 
     [Test]
-    public void GetInheritanceRootClass ()
+    public void IsAssignableFrom ()
     {
-      ClassDefinition expected = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Company)];
-      Assert.That(_distributorClass.GetInheritanceRootClass(), Is.SameAs(expected));
+      _personClass.SetDerivedClasses(new []{ _customerClass});
+      _customerClass.SetDerivedClasses(Array.Empty<ClassDefinition>());
+      _organizationalUnitClass.SetDerivedClasses(Array.Empty<ClassDefinition>());
+
+      Assert.That(_domainBaseClass.IsAssignableFrom(_domainBaseClass), Is.True);
+      Assert.That(_domainBaseClass.IsAssignableFrom(_customerClass), Is.True);
+      Assert.That(_domainBaseClass.IsAssignableFrom(_personClass), Is.True);
+      Assert.That(_personClass.IsAssignableFrom(_customerClass), Is.True);
+
+      Assert.That(_customerClass.IsAssignableFrom(_domainBaseClass), Is.False);
+      Assert.That(_personClass.IsAssignableFrom(_domainBaseClass), Is.False);
+      Assert.That(_customerClass.IsAssignableFrom(_personClass), Is.False);
+
+      Assert.That(_personClass.IsAssignableFrom(_organizationalUnitClass), Is.False);
+      Assert.That(_organizationalUnitClass.IsAssignableFrom(_personClass), Is.False);
     }
 
     [Test]
     public void GetAllDerivedClasses ()
     {
-      ClassDefinition companyClass = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Company)];
+      ClassDefinition companyClass = FakeMappingConfiguration.Current.GetClassDefinition(typeof(Company));
       var allDerivedClasses = companyClass.GetAllDerivedClasses();
       Assert.That(allDerivedClasses, Is.Not.Null);
       Assert.That(allDerivedClasses.Length, Is.EqualTo(4));
 
-      Assert.That(allDerivedClasses.Any(cd => cd.ClassType == typeof(Customer)), Is.True);
-      Assert.That(allDerivedClasses.Any(cd => cd.ClassType == typeof(Partner)), Is.True);
-      Assert.That(allDerivedClasses.Any(cd => cd.ClassType == typeof(Supplier)), Is.True);
-      Assert.That(allDerivedClasses.Any(cd => cd.ClassType == typeof(Distributor)), Is.True);
+      Assert.That(allDerivedClasses.Any(cd => cd.Type == typeof(Customer)), Is.True);
+      Assert.That(allDerivedClasses.Any(cd => cd.Type == typeof(Partner)), Is.True);
+      Assert.That(allDerivedClasses.Any(cd => cd.Type == typeof(Supplier)), Is.True);
+      Assert.That(allDerivedClasses.Any(cd => cd.Type == typeof(Distributor)), Is.True);
     }
 
     [Test]
@@ -953,7 +768,7 @@ public void IsSameOrBaseClassOfTrueWithSameClass ()
     [Test]
     public void IsSameOrBaseClassOfTrueWithBaseClass ()
     {
-      ClassDefinition companyClass = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Company)];
+      ClassDefinition companyClass = FakeMappingConfiguration.Current.GetClassDefinition(typeof(Company));
 
       Assert.That(companyClass.IsSameOrBaseClassOf(_distributorClass), Is.True);
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassReflectorTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassReflectorTest.cs
index 565604a4c9..7d3cb06a25 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassReflectorTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassReflectorTest.cs
@@ -33,14 +33,14 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   [TestFixture]
   public class ClassReflectorTest : MappingReflectionTestBase
   {
-    private ClassDefinitionChecker _classDefinitionChecker;
+    private TypeDefinitionChecker _typeDefinitionChecker;
     private RelationEndPointDefinitionChecker _endPointDefinitionChecker;
 
     public override void SetUp ()
     {
       base.SetUp();
 
-      _classDefinitionChecker = new ClassDefinitionChecker();
+      _typeDefinitionChecker = new TypeDefinitionChecker();
       _endPointDefinitionChecker = new RelationEndPointDefinitionChecker();
     }
 
@@ -74,7 +74,7 @@ public void GetMetadata_ForBaseClass ()
       var actual = classReflector.GetMetadata(null);
 
       Assert.That(actual, Is.Not.Null);
-      _classDefinitionChecker.Check(expected, actual);
+      _typeDefinitionChecker.Check(expected, actual);
       _endPointDefinitionChecker.Check(expected.MyRelationEndPointDefinitions, actual.MyRelationEndPointDefinitions, false);
     }
 
@@ -100,7 +100,7 @@ public void GetMetadata_ForDerivedClass ()
       var actual = classReflector.GetMetadata(baseClassDefinition);
 
       Assert.That(actual, Is.Not.Null);
-      _classDefinitionChecker.Check(expected, actual);
+      _typeDefinitionChecker.Check(expected, actual);
       _endPointDefinitionChecker.Check(expected.MyRelationEndPointDefinitions, actual.MyRelationEndPointDefinitions, false);
     }
 
@@ -171,7 +171,7 @@ public void GetMetadata_ForClassWithVirtualRelationEndPoints ()
           .Setup(stub => stub.IsNullable(It.Is<IPropertyInformation>(pi => pi.Name == "BidirectionalOneToManyForVirtualCollection")))
           .Returns(true);
 
-      var classDefinitionFake = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
+      var classDefinitionFake = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
 
       SortExpressionDefinitionProviderStub
           .Setup(_ => _.GetSortExpression(It.IsAny<IPropertyInformation>(), It.IsAny<ClassDefinition>(), null))
@@ -200,13 +200,13 @@ public void GetMetadata_ForClassWithVirtualRelationEndPoints ()
       foreach (var actualEndPoint in actual.MyRelationEndPointDefinitions)
       {
         var endPointStub = new Mock<IRelationEndPointDefinition>();
-        endPointStub.Setup(stub => stub.ClassDefinition).Returns(classDefinitionFake);
+        endPointStub.Setup(stub => stub.TypeDefinition).Returns(classDefinitionFake);
         ((IRelationEndPointDefinitionSetter)actualEndPoint).SetRelationDefinition(
             new RelationDefinition("fake: " + actualEndPoint.PropertyName, actualEndPoint, endPointStub.Object));
       }
 
       Assert.That(actual, Is.Not.Null);
-      _classDefinitionChecker.Check(expected, actual);
+      _typeDefinitionChecker.Check(expected, actual);
       _endPointDefinitionChecker.Check(expected.MyRelationEndPointDefinitions, actual.MyRelationEndPointDefinitions, false);
     }
 
@@ -518,11 +518,11 @@ private void CreateEndPointDefinitionsForClassWithVirtualRelationEndPoints (Clas
               false,
               CreateSortExpressionDefinition("NoAttributeForVirtualCollection")));
 
-      var classDefinitionFake = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
+      var classDefinitionFake = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
       foreach (var endPoint in endPoints)
       {
         var endPointStub = new Mock<IRelationEndPointDefinition>();
-        endPointStub.Setup(stub => stub.ClassDefinition).Returns(classDefinitionFake);
+        endPointStub.Setup(stub => stub.TypeDefinition).Returns(classDefinitionFake);
         ((IRelationEndPointDefinitionSetter)endPoint).SetRelationDefinition(new RelationDefinition("fake: " + endPoint.PropertyName, endPoint, endPointStub.Object));
       }
 
@@ -603,13 +603,14 @@ private IPropertyInformation GetPropertyInfo (Type declaringType, string shortPr
       return PropertyInfoAdapter.Create(propertyInfo);
     }
 
-    private ClassDefinition CreateClassDefinition (string id, Type classType, bool isAbstract, ClassDefinition baseClass = null)
+    private ClassDefinition CreateClassDefinition (string id, Type classType, bool isAbstract, ClassDefinition baseClass = null, params InterfaceDefinition[] implementedInterfaces)
     {
         return new ClassDefinition(
                 id,
                 classType,
                 isAbstract,
                 baseClass,
+                implementedInterfaces,
                 null,
                 DefaultStorageClass.Persistent,
                 new PersistentMixinFinderStub(classType),
@@ -618,12 +619,12 @@ private ClassDefinition CreateClassDefinition (string id, Type classType, bool i
 
     private PropertyDefinition CreatePersistentPropertyDefinition (
         ClassDefinition classDefinition,
-        Type declaringClassType,
+        Type declaringType,
         string propertyName,
         bool isNullable,
         int? maxLength)
     {
-      var propertyInfoAdapter = PropertyInfoAdapter.Create(declaringClassType.GetProperty(propertyName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance));
+      var propertyInfoAdapter = PropertyInfoAdapter.Create(declaringType.GetProperty(propertyName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance));
       var fullName = MappingConfiguration.Current.NameResolver.GetPropertyName(propertyInfoAdapter);
       return new PropertyDefinition(
           classDefinition,
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/DomainObjectCollectionRelationEndPointDefinitionFactory.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/DomainObjectCollectionRelationEndPointDefinitionFactory.cs
index 60fcb88403..8c0a65c9c6 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/DomainObjectCollectionRelationEndPointDefinitionFactory.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/DomainObjectCollectionRelationEndPointDefinitionFactory.cs
@@ -25,7 +25,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   public static class DomainObjectCollectionRelationEndPointDefinitionFactory
   {
     public static DomainObjectCollectionRelationEndPointDefinition Create (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         bool isMandatory,
         Type propertyType,
@@ -34,19 +34,19 @@ public static DomainObjectCollectionRelationEndPointDefinition Create (
       var propertyInformationStub = new Mock<IPropertyInformation>();
       propertyInformationStub.Setup(stub => stub.Name).Returns(propertyName);
       propertyInformationStub.Setup(stub => stub.PropertyType).Returns(propertyType);
-      propertyInformationStub.Setup(stub => stub.DeclaringType).Returns(TypeAdapter.Create(classDefinition.ClassType));
+      propertyInformationStub.Setup(stub => stub.DeclaringType).Returns(TypeAdapter.Create(typeDefinition.Type));
 
       return new DomainObjectCollectionRelationEndPointDefinition(
-          classDefinition, propertyName, isMandatory, sortExpressionDefinition, propertyInformationStub.Object);
+          typeDefinition, propertyName, isMandatory, sortExpressionDefinition, propertyInformationStub.Object);
     }
 
     public static DomainObjectCollectionRelationEndPointDefinition Create (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         bool isMandatory,
         Type propertyType)
     {
-      return Create(classDefinition, propertyName, isMandatory, propertyType, new Lazy<SortExpressionDefinition>(() => null));
+      return Create(typeDefinition, propertyName, isMandatory, propertyType, new Lazy<SortExpressionDefinition>(() => null));
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/DomainObjectCollectionRelationEndPointDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/DomainObjectCollectionRelationEndPointDefinitionTest.cs
index 374232a116..472ee55d45 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/DomainObjectCollectionRelationEndPointDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/DomainObjectCollectionRelationEndPointDefinitionTest.cs
@@ -27,30 +27,30 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   [TestFixture]
   public class DomainObjectCollectionRelationEndPointDefinitionTest : MappingReflectionTestBase
   {
-    private ClassDefinition _customerClassDefinition;
+    private TypeDefinition _customerTypeDefinition;
     private DomainObjectCollectionRelationEndPointDefinition _customerOrdersEndPoint;
 
-    private ClassDefinition _orderClassDefinition;
+    private TypeDefinition _orderTypeDefinition;
 
     public override void SetUp ()
     {
       base.SetUp();
 
-      _customerClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Customer));
+      _customerTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Customer));
       _customerOrdersEndPoint = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _customerClassDefinition,
+          _customerTypeDefinition,
           "Orders",
           false,
           typeof(OrderCollection));
 
-      _orderClassDefinition = CreateOrderDefinition_WithEmptyMembers_AndDerivedClasses();
+      _orderTypeDefinition = CreateOrderDefinition_WithEmptyMembers_AndDerivedClasses();
     }
 
     [Test]
     public void InitializeWithPropertyType ()
     {
       var endPoint = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _orderClassDefinition,
+          _orderTypeDefinition,
           "VirtualEndPoint",
           true,
           typeof(OrderCollection));
@@ -87,7 +87,7 @@ public void SetRelationDefinition ()
     public void GetSortExpression_Null ()
     {
       var endPoint = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _orderClassDefinition,
+          _orderTypeDefinition,
           "OrderItems",
           false,
           typeof(ObjectList<OrderItem>),
@@ -111,7 +111,7 @@ public void GetSortExpression_NonNull ()
           });
 
       var endPoint = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _orderClassDefinition,
+          _orderTypeDefinition,
           "OrderItems",
           false,
           typeof(ObjectList<OrderItem>),
@@ -127,15 +127,15 @@ public void GetSortExpression_NonNull ()
     [Test]
     public void PropertyInfo ()
     {
-      ClassDefinition orderClassDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
+      TypeDefinition orderTypeDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
       DomainObjectCollectionRelationEndPointDefinition relationEndPointDefinition =
-          (DomainObjectCollectionRelationEndPointDefinition)orderClassDefinition.GetRelationEndPointDefinition(typeof(Order) + ".OrderItems");
+          (DomainObjectCollectionRelationEndPointDefinition)orderTypeDefinition.GetRelationEndPointDefinition(typeof(Order) + ".OrderItems");
       Assert.That(relationEndPointDefinition.PropertyInfo, Is.EqualTo(PropertyInfoAdapter.Create(typeof(Order).GetProperty("OrderItems"))));
     }
 
-    private static ClassDefinition CreateOrderDefinition_WithEmptyMembers_AndDerivedClasses ()
+    private static TypeDefinition CreateOrderDefinition_WithEmptyMembers_AndDerivedClasses ()
     {
-      return ClassDefinitionObjectMother.CreateClassDefinition_WithEmptyMembers_AndDerivedClasses("Order", classType: typeof(Order));
+      return TypeDefinitionObjectMother.CreateClassDefinition_WithEmptyMembers_AndDerivedClasses("Order", classType: typeof(Order));
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/FakeMappingConfiguration.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/FakeMappingConfiguration.cs
index 084ae738ef..2a10bc5f12 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/FakeMappingConfiguration.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/FakeMappingConfiguration.cs
@@ -60,7 +60,7 @@ public static void Reset ()
 
     private readonly StorageProviderDefinition _defaultStorageProviderDefinition;
     private readonly StorageProviderDefinition _nonPersistentProviderDefinition;
-    private readonly ReadOnlyDictionary<Type, ClassDefinition> _typeDefinitions;
+    private readonly ReadOnlyDictionary<Type, TypeDefinition> _typeDefinitions;
     private readonly ReadOnlyDictionary<string, RelationDefinition> _relationDefinitions;
 
     // construction and disposing
@@ -70,11 +70,11 @@ private FakeMappingConfiguration ()
       _defaultStorageProviderDefinition = new UnitTestStorageProviderStubDefinition("DefaultStorageProvider");
       _nonPersistentProviderDefinition =
           new NonPersistentProviderDefinition("NonPersistentStorageProvider", new NonPersistentStorageObjectFactory());
-      _typeDefinitions = new ReadOnlyDictionary<Type, ClassDefinition>(CreateClassDefinitions());
+      _typeDefinitions = new ReadOnlyDictionary<Type, TypeDefinition>(CreateTypeDefinitions());
       _relationDefinitions = new ReadOnlyDictionary<string, RelationDefinition>(CreateRelationDefinitions());
 
-      foreach (ClassDefinition classDefinition in _typeDefinitions.Values)
-        classDefinition.SetReadOnly();
+      foreach (var typeDefinition in _typeDefinitions.Values)
+        typeDefinition.SetReadOnly();
     }
 
     // methods and properties
@@ -89,7 +89,7 @@ public StorageProviderDefinition NonPersistentStorageProviderDefinition
       get { return _nonPersistentProviderDefinition; }
     }
 
-    public ReadOnlyDictionary<Type, ClassDefinition> TypeDefinitions
+    public ReadOnlyDictionary<Type, TypeDefinition> TypeDefinitions
     {
       get { return _typeDefinitions; }
     }
@@ -99,77 +99,83 @@ public ReadOnlyDictionary<string, RelationDefinition> RelationDefinitions
       get { return _relationDefinitions; }
     }
 
+    public ClassDefinition GetClassDefinition (Type type)
+    {
+        return (ClassDefinition)TypeDefinitions[type];
+    }
+
     #region Methods for creating class definitions
 
-    private Dictionary<Type, ClassDefinition> CreateClassDefinitions ()
+    private Dictionary<Type, TypeDefinition> CreateTypeDefinitions ()
     {
-      var classDefinitions = new List<ClassDefinition>();
+      var typeDefinitions = new List<TypeDefinition>();
 
       ClassDefinition company = CreateCompanyDefinition(null);
-      classDefinitions.Add(company);
+      typeDefinitions.Add(company);
 
       ClassDefinition customer = CreateCustomerDefinition(company);
-      classDefinitions.Add(customer);
+      typeDefinitions.Add(customer);
 
       ClassDefinition partner = CreatePartnerDefinition(company);
-      classDefinitions.Add(partner);
+      typeDefinitions.Add(partner);
 
       ClassDefinition supplier = CreateSupplierDefinition(partner);
-      classDefinitions.Add(supplier);
+      typeDefinitions.Add(supplier);
 
       ClassDefinition distributor = CreateDistributorDefinition(partner);
-      classDefinitions.Add(distributor);
+      typeDefinitions.Add(distributor);
 
-      classDefinitions.Add(CreateOrderDefinition(null));
-      classDefinitions.Add(CreateOrderViewModelDefinition(null));
-      classDefinitions.Add(CreateOrderTicketDefinition(null));
-      classDefinitions.Add(CreateOrderItemDefinition(null));
+      typeDefinitions.Add(CreateOrderDefinition(null));
+      typeDefinitions.Add(CreateOrderViewModelDefinition(null));
+      typeDefinitions.Add(CreateOrderTicketDefinition(null));
+      typeDefinitions.Add(CreateOrderItemDefinition(null));
 
-      classDefinitions.Add(CreateProductDefinition(null));
-      classDefinitions.Add(CreateProductReviewDefinition(null));
+      typeDefinitions.Add(CreateProductDefinition(null));
+      typeDefinitions.Add(CreateProductReviewDefinition(null));
 
       ClassDefinition officialDefinition = CreateOfficialDefinition(null);
-      classDefinitions.Add(officialDefinition);
-      classDefinitions.Add(CreateSpecialOfficialDefinition(officialDefinition));
+      typeDefinitions.Add(officialDefinition);
+      typeDefinitions.Add(CreateSpecialOfficialDefinition(officialDefinition));
 
-      classDefinitions.Add(CreateCeoDefinition(null));
-      classDefinitions.Add(CreatePersonDefinition(null));
+      typeDefinitions.Add(CreateCeoDefinition(null));
+      typeDefinitions.Add(CreatePersonDefinition(null));
 
-      classDefinitions.Add(CreateClientDefinition(null));
-      classDefinitions.Add(CreateLocationDefinition(null));
+      typeDefinitions.Add(CreateClientDefinition(null));
+      typeDefinitions.Add(CreateLocationDefinition(null));
 
       ClassDefinition fileSystemItemDefinition = CreateFileSystemItemDefinition(null);
-      classDefinitions.Add(fileSystemItemDefinition);
-      classDefinitions.Add(CreateFolderDefinition(fileSystemItemDefinition));
-      classDefinitions.Add(CreateFileDefinition(fileSystemItemDefinition));
-
-      classDefinitions.Add(CreateClassWithOptionalOneToOneRelationAndOppositeDerivedClassDefinition(null));
-      classDefinitions.Add(CreateClassWithAllDataTypesDefinition(null));
-      classDefinitions.Add(CreateClassWithDefaultStorageClassTransaction(null));
-      classDefinitions.Add(CreateClassWithGuidKeyDefinition(null));
-      classDefinitions.Add(CreateClassWithInvalidKeyTypeDefinition(null));
-      classDefinitions.Add(CreateClassWithoutIDColumnDefinition(null));
-      classDefinitions.Add(CreateClassWithoutClassIDColumnDefinition(null));
-      classDefinitions.Add(CreateClassWithoutTimestampColumnDefinition(null));
-      classDefinitions.Add(CreateClassWithValidRelationsDefinition(null));
-      classDefinitions.Add(CreateClassWithInvalidRelationDefinition(null));
-      classDefinitions.Add(CreateIndustrialSectorDefinition(null));
-      classDefinitions.Add(CreateEmployeeDefinition(null));
-      classDefinitions.Add(CreateComputerDefinition(null));
-      classDefinitions.Add(CreateClassWithRelatedClassIDColumnAndNoInheritanceDefinition(null));
+      typeDefinitions.Add(fileSystemItemDefinition);
+      typeDefinitions.Add(CreateFolderDefinition(fileSystemItemDefinition));
+      typeDefinitions.Add(CreateFileDefinition(fileSystemItemDefinition));
+
+      typeDefinitions.Add(CreateClassWithOptionalOneToOneRelationAndOppositeDerivedClassDefinition(null));
+      typeDefinitions.Add(CreateClassWithAllDataTypesDefinition(null));
+      typeDefinitions.Add(CreateClassWithDefaultStorageClassTransaction(null));
+      typeDefinitions.Add(CreateClassWithGuidKeyDefinition(null));
+      typeDefinitions.Add(CreateClassWithInvalidKeyTypeDefinition(null));
+      typeDefinitions.Add(CreateClassWithoutIDColumnDefinition(null));
+      typeDefinitions.Add(CreateClassWithoutClassIDColumnDefinition(null));
+      typeDefinitions.Add(CreateClassWithoutTimestampColumnDefinition(null));
+      typeDefinitions.Add(CreateClassWithValidRelationsDefinition(null));
+      typeDefinitions.Add(CreateClassWithInvalidRelationDefinition(null));
+      typeDefinitions.Add(CreateIndustrialSectorDefinition(null));
+      typeDefinitions.Add(CreateEmployeeDefinition(null));
+      typeDefinitions.Add(CreateComputerDefinition(null));
+      typeDefinitions.Add(CreateClassWithRelatedClassIDColumnAndNoInheritanceDefinition(null));
 
       var targetClassForPersistentMixinDefinition = CreateTargetClassForPersistentMixinDefinition(null);
-      classDefinitions.Add(targetClassForPersistentMixinDefinition);
+      typeDefinitions.Add(targetClassForPersistentMixinDefinition);
       var derivedTargetClassForPersistentMixinDefinition = CreateDerivedTargetClassForPersistentMixinDefinition(targetClassForPersistentMixinDefinition);
-      classDefinitions.Add(derivedTargetClassForPersistentMixinDefinition);
+      typeDefinitions.Add(derivedTargetClassForPersistentMixinDefinition);
       var derivedDerivedTargetClassForPersistentMixinDefinition = CreateDerivedDerivedTargetClassForPersistentMixinDefinition(derivedTargetClassForPersistentMixinDefinition);
-      classDefinitions.Add(derivedDerivedTargetClassForPersistentMixinDefinition);
+      typeDefinitions.Add(derivedDerivedTargetClassForPersistentMixinDefinition);
       var relationTargetForPersistentMixinDefinition = CreateRelationTargetForPersistentMixinDefinition(null);
-      classDefinitions.Add(relationTargetForPersistentMixinDefinition);
+      typeDefinitions.Add(relationTargetForPersistentMixinDefinition);
 
-      CalculateAndSetDerivedClasses(classDefinitions);
+      // TODO R2I Update set logic to also include setting interfaces
+      CalculateAndSetDerivedClasses(typeDefinitions.OfType<ClassDefinition>());
 
-      return classDefinitions.ToDictionary(cd => cd.ClassType);
+      return typeDefinitions.ToDictionary(cd => cd.Type);
     }
 
     private void CalculateAndSetDerivedClasses (IEnumerable<ClassDefinition> classDefinitions)
@@ -189,9 +195,9 @@ private void CalculateAndSetDerivedClasses (IEnumerable<ClassDefinition> classDe
       }
     }
 
-    private ClassDefinition CreateCompanyDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateCompanyDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition company = CreateClassDefinition("Company", "Company", typeof(Company), false, baseClass);
+      ClassDefinition company = CreateClassDefinition("Company", "Company", typeof(Company), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -203,9 +209,9 @@ private ClassDefinition CreateCompanyDefinition (ClassDefinition baseClass)
       return company;
     }
 
-    private ClassDefinition CreateCustomerDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateCustomerDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition customer = CreateClassDefinition("Customer", "Company", typeof(Customer), false, baseClass);
+      ClassDefinition customer = CreateClassDefinition("Customer", "Company", typeof(Customer), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -217,9 +223,9 @@ private ClassDefinition CreateCustomerDefinition (ClassDefinition baseClass)
       return customer;
     }
 
-    private ClassDefinition CreatePartnerDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreatePartnerDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition partner = CreateClassDefinition("Partner", "Company", typeof(Partner), false, baseClass);
+      ClassDefinition partner = CreateClassDefinition("Partner", "Company", typeof(Partner), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -229,9 +235,9 @@ private ClassDefinition CreatePartnerDefinition (ClassDefinition baseClass)
       return partner;
     }
 
-    private ClassDefinition CreateSupplierDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateSupplierDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition supplier = CreateClassDefinition("Supplier", "Company", typeof(Supplier), false, baseClass);
+      ClassDefinition supplier = CreateClassDefinition("Supplier", "Company", typeof(Supplier), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -241,9 +247,9 @@ private ClassDefinition CreateSupplierDefinition (ClassDefinition baseClass)
       return supplier;
     }
 
-    private ClassDefinition CreateDistributorDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateDistributorDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition distributor = CreateClassDefinition("Distributor", "Company", typeof(Distributor), false, baseClass);
+      ClassDefinition distributor = CreateClassDefinition("Distributor", "Company", typeof(Distributor), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -253,9 +259,9 @@ private ClassDefinition CreateDistributorDefinition (ClassDefinition baseClass)
       return distributor;
     }
 
-    private ClassDefinition CreateOrderDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateOrderDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition order = CreateClassDefinition("Order", "Order", typeof(Order), false, baseClass);
+      ClassDefinition order = CreateClassDefinition("Order", "Order", typeof(Order), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -271,10 +277,10 @@ private ClassDefinition CreateOrderDefinition (ClassDefinition baseClass)
       return order;
     }
 
-    private ClassDefinition CreateOrderViewModelDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateOrderViewModelDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition orderViewModel = CreateClassDefinitionForNonPersistentProvider(
-          "OrderViewModel", typeof(OrderViewModel), false, baseClass);
+          "OrderViewModel", typeof(OrderViewModel), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -286,10 +292,10 @@ private ClassDefinition CreateOrderViewModelDefinition (ClassDefinition baseClas
       return orderViewModel;
     }
 
-    private ClassDefinition CreateOfficialDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateOfficialDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition official = CreateClassDefinition(
-          "Official", "Official", typeof(Official), false, baseClass);
+          "Official", "Official", typeof(Official), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -299,17 +305,17 @@ private ClassDefinition CreateOfficialDefinition (ClassDefinition baseClass)
       return official;
     }
 
-    private ClassDefinition CreateSpecialOfficialDefinition (ClassDefinition officialDefinition)
+    private ClassDefinition CreateSpecialOfficialDefinition (ClassDefinition officialDefinition, params InterfaceDefinition[] implementedInterfaces)
     {
-      var specialOfficial = CreateClassDefinition("SpecialOfficial", "Official", typeof(SpecialOfficial), false, officialDefinition);
+      var specialOfficial = CreateClassDefinition("SpecialOfficial", "Official", typeof(SpecialOfficial), false, officialDefinition, implementedInterfaces);
       specialOfficial.SetPropertyDefinitions(new PropertyDefinitionCollection());
 
       return specialOfficial;
     }
 
-    private ClassDefinition CreateOrderTicketDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateOrderTicketDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition orderTicket = CreateClassDefinition("OrderTicket", "OrderTicket", typeof(OrderTicket), false, baseClass);
+      ClassDefinition orderTicket = CreateClassDefinition("OrderTicket", "OrderTicket", typeof(OrderTicket), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -323,9 +329,9 @@ private ClassDefinition CreateOrderTicketDefinition (ClassDefinition baseClass)
       return orderTicket;
     }
 
-    private ClassDefinition CreateOrderItemDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateOrderItemDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition orderItem = CreateClassDefinition("OrderItem", "OrderItem", typeof(OrderItem), false, baseClass);
+      ClassDefinition orderItem = CreateClassDefinition("OrderItem", "OrderItem", typeof(OrderItem), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -339,9 +345,9 @@ private ClassDefinition CreateOrderItemDefinition (ClassDefinition baseClass)
       return orderItem;
     }
 
-    private ClassDefinition CreateProductDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateProductDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      var product = CreateClassDefinition("Product", "Product", typeof(Product), false, baseClass);
+      var product = CreateClassDefinition("Product", "Product", typeof(Product), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -353,9 +359,9 @@ private ClassDefinition CreateProductDefinition (ClassDefinition baseClass)
       return product;
     }
 
-    private ClassDefinition CreateProductReviewDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateProductReviewDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      var productReview = CreateClassDefinition("ProductReview", "ProductReview", typeof(ProductReview), false, baseClass);
+      var productReview = CreateClassDefinition("ProductReview", "ProductReview", typeof(ProductReview), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -371,10 +377,10 @@ private ClassDefinition CreateProductReviewDefinition (ClassDefinition baseClass
       return productReview;
     }
 
-    private ClassDefinition CreateCeoDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateCeoDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition ceo = CreateClassDefinition(
-          "Ceo", "Ceo", typeof(Ceo), false, baseClass);
+          "Ceo", "Ceo", typeof(Ceo), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -387,10 +393,10 @@ private ClassDefinition CreateCeoDefinition (ClassDefinition baseClass)
       return ceo;
     }
 
-    private ClassDefinition CreatePersonDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreatePersonDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition person = CreateClassDefinition(
-          "Person", "Person", typeof(Person), false, baseClass);
+          "Person", "Person", typeof(Person), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -401,10 +407,10 @@ private ClassDefinition CreatePersonDefinition (ClassDefinition baseClass)
       return person;
     }
 
-    private ClassDefinition CreateClientDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateClientDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition client = CreateClassDefinition(
-          "Client", "Client", typeof(Client), false, baseClass);
+          "Client", "Client", typeof(Client), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -414,10 +420,10 @@ private ClassDefinition CreateClientDefinition (ClassDefinition baseClass)
       return client;
     }
 
-    private ClassDefinition CreateLocationDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateLocationDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition location = CreateClassDefinition(
-          "Location", "Location", typeof(Location), false, baseClass);
+          "Location", "Location", typeof(Location), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -427,10 +433,10 @@ private ClassDefinition CreateLocationDefinition (ClassDefinition baseClass)
       return location;
     }
 
-    private ClassDefinition CreateFileSystemItemDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateFileSystemItemDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition fileSystemItem = CreateClassDefinition(
-          "FileSystemItem", "FileSystemItem", typeof(FileSystemItem), false, baseClass);
+          "FileSystemItem", "FileSystemItem", typeof(FileSystemItem), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -440,28 +446,28 @@ private ClassDefinition CreateFileSystemItemDefinition (ClassDefinition baseClas
       return fileSystemItem;
     }
 
-    private ClassDefinition CreateFolderDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateFolderDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition folder = CreateClassDefinition(
-          "Folder", "FileSystemItem", typeof(Folder), false, baseClass);
+          "Folder", "FileSystemItem", typeof(Folder), false, baseClass, implementedInterfaces);
       folder.SetPropertyDefinitions(new PropertyDefinitionCollection());
 
       return folder;
     }
 
-    private ClassDefinition CreateFileDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateFileDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition file = CreateClassDefinition(
-          "File", "FileSystemItem", typeof(File), false, baseClass);
+          "File", "FileSystemItem", typeof(File), false, baseClass, implementedInterfaces);
       file.SetPropertyDefinitions(new PropertyDefinitionCollection());
 
       return file;
     }
 
     //TODO: remove Date and NaDate properties
-    private ClassDefinition CreateClassWithAllDataTypesDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateClassWithAllDataTypesDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition classWithAllDataTypes = CreateClassDefinition("ClassWithAllDataTypes", "TableWithAllDataTypes", typeof(ClassWithAllDataTypes), false, baseClass);
+      ClassDefinition classWithAllDataTypes = CreateClassDefinition("ClassWithAllDataTypes", "TableWithAllDataTypes", typeof(ClassWithAllDataTypes), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -568,14 +574,15 @@ private ClassDefinition CreateClassWithAllDataTypesDefinition (ClassDefinition b
       return classWithAllDataTypes;
     }
 
-    private ClassDefinition CreateClassWithDefaultStorageClassTransaction (ClassDefinition baseClass)
+    private ClassDefinition CreateClassWithDefaultStorageClassTransaction (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition classDefinition = CreateClassDefinition(
           "ClassWithDefaultStorageClassTransaction",
           "TableWithDefaultStorageClassTransaction",
           typeof(ClassWithDefaultStorageClassTransaction),
           false,
-          baseClass);
+          baseClass,
+          implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -589,59 +596,63 @@ private ClassDefinition CreateClassWithDefaultStorageClassTransaction (ClassDefi
       return classDefinition;
     }
 
-    private ClassDefinition CreateClassWithGuidKeyDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateClassWithGuidKeyDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition classDefinition = CreateClassDefinition(
           "ClassWithGuidKey",
           "TableWithGuidKey",
           typeof(ClassWithGuidKey),
           false,
-          baseClass);
+          baseClass,
+          implementedInterfaces);
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
 
       return classDefinition;
     }
 
-    private ClassDefinition CreateClassWithInvalidKeyTypeDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateClassWithInvalidKeyTypeDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition classDefinition = CreateClassDefinition(
           "ClassWithKeyOfInvalidType",
           "TableWithKeyOfInvalidType",
           typeof(ClassWithKeyOfInvalidType),
           false,
-          baseClass);
+          baseClass,
+          implementedInterfaces);
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
 
       return classDefinition;
     }
 
-    private ClassDefinition CreateClassWithoutIDColumnDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateClassWithoutIDColumnDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition classDefinition = CreateClassDefinition(
           "ClassWithoutIDColumn",
           "TableWithoutIDColumn",
           typeof(ClassWithoutIDColumn),
           false,
-          baseClass);
+          baseClass,
+          implementedInterfaces);
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
 
       return classDefinition;
     }
 
-    private ClassDefinition CreateClassWithoutClassIDColumnDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateClassWithoutClassIDColumnDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition classDefinition = CreateClassDefinition(
           "ClassWithoutClassIDColumn",
           "TableWithoutClassIDColumn",
           typeof(ClassWithoutClassIDColumn),
           false,
-          baseClass);
+          baseClass,
+          implementedInterfaces);
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
 
       return classDefinition;
     }
 
-    private ClassDefinition CreateClassWithoutTimestampColumnDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateClassWithoutTimestampColumnDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition classDefinition =
           CreateClassDefinition(
@@ -649,20 +660,22 @@ private ClassDefinition CreateClassWithoutTimestampColumnDefinition (ClassDefini
               "TableWithoutTimestampColumn",
               typeof(ClassWithoutTimestampColumn),
               false,
-              baseClass);
+              baseClass,
+              implementedInterfaces);
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
 
       return classDefinition;
     }
 
-    private ClassDefinition CreateClassWithValidRelationsDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateClassWithValidRelationsDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition classDefinition = CreateClassDefinition(
           "ClassWithValidRelations",
           "TableWithValidRelations",
           typeof(ClassWithValidRelations),
           false,
-          baseClass);
+          baseClass,
+          implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -675,14 +688,15 @@ private ClassDefinition CreateClassWithValidRelationsDefinition (ClassDefinition
       return classDefinition;
     }
 
-    private ClassDefinition CreateClassWithInvalidRelationDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateClassWithInvalidRelationDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition classDefinition = CreateClassDefinition(
           "ClassWithInvalidRelation",
           "TableWithInvalidRelation",
           typeof(ClassWithInvalidRelation),
           false,
-          baseClass);
+          baseClass,
+          implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -692,7 +706,7 @@ private ClassDefinition CreateClassWithInvalidRelationDefinition (ClassDefinitio
       return classDefinition;
     }
 
-    private ClassDefinition CreateClassWithOptionalOneToOneRelationAndOppositeDerivedClassDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateClassWithOptionalOneToOneRelationAndOppositeDerivedClassDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition classDefinition =
           CreateClassDefinition(
@@ -700,7 +714,8 @@ private ClassDefinition CreateClassWithOptionalOneToOneRelationAndOppositeDerive
               "TableWithOptionalOneToOneRelationAndOppositeDerivedClass",
               typeof(ClassWithOptionalOneToOneRelationAndOppositeDerivedClass),
               false,
-              baseClass);
+              baseClass,
+              implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -710,9 +725,9 @@ private ClassDefinition CreateClassWithOptionalOneToOneRelationAndOppositeDerive
       return classDefinition;
     }
 
-    private ClassDefinition CreateIndustrialSectorDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateIndustrialSectorDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition industrialSector = CreateClassDefinition("IndustrialSector", "IndustrialSector", typeof(IndustrialSector), false, baseClass);
+      ClassDefinition industrialSector = CreateClassDefinition("IndustrialSector", "IndustrialSector", typeof(IndustrialSector), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -723,9 +738,9 @@ private ClassDefinition CreateIndustrialSectorDefinition (ClassDefinition baseCl
       return industrialSector;
     }
 
-    private ClassDefinition CreateEmployeeDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateEmployeeDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition employee = CreateClassDefinition("Employee", "Employee", typeof(Employee), false, baseClass);
+      ClassDefinition employee = CreateClassDefinition("Employee", "Employee", typeof(Employee), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -738,7 +753,7 @@ private ClassDefinition CreateEmployeeDefinition (ClassDefinition baseClass)
       return employee;
     }
 
-    private ClassDefinition CreateTargetClassForPersistentMixinDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateTargetClassForPersistentMixinDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition targetClassForPersistentMixin = CreateClassDefinition(
           "TargetClassForPersistentMixin",
@@ -746,6 +761,7 @@ private ClassDefinition CreateTargetClassForPersistentMixinDefinition (ClassDefi
           typeof(TargetClassForPersistentMixin),
           false,
           baseClass,
+          implementedInterfaces,
           typeof(MixinAddingPersistentProperties));
 
       var properties = new List<PropertyDefinition>();
@@ -772,35 +788,37 @@ private ClassDefinition CreateTargetClassForPersistentMixinDefinition (ClassDefi
       return targetClassForPersistentMixin;
     }
 
-    private ClassDefinition CreateDerivedTargetClassForPersistentMixinDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateDerivedTargetClassForPersistentMixinDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition derivedTargetClassForPersistentMixin = CreateClassDefinition(
           "DerivedTargetClassForPersistentMixin",
           "MixedDomains_Target",
           typeof(DerivedTargetClassForPersistentMixin),
           false,
-          baseClass);
+          baseClass,
+          implementedInterfaces);
       derivedTargetClassForPersistentMixin.SetPropertyDefinitions(new PropertyDefinitionCollection());
 
       return derivedTargetClassForPersistentMixin;
     }
 
-    private ClassDefinition CreateDerivedDerivedTargetClassForPersistentMixinDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateDerivedDerivedTargetClassForPersistentMixinDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition derivedDerivedTargetClassForPersistentMixin = CreateClassDefinition(
           "DerivedDerivedTargetClassForPersistentMixin",
           "MixedDomains_Target",
           typeof(DerivedDerivedTargetClassForPersistentMixin),
           false,
-          baseClass);
+          baseClass,
+          implementedInterfaces);
       derivedDerivedTargetClassForPersistentMixin.SetPropertyDefinitions(new PropertyDefinitionCollection());
 
       return derivedDerivedTargetClassForPersistentMixin;
     }
 
-    private ClassDefinition CreateComputerDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateComputerDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
-      ClassDefinition computer = CreateClassDefinition("Computer", "Computer", typeof(Computer), false, baseClass);
+      ClassDefinition computer = CreateClassDefinition("Computer", "Computer", typeof(Computer), false, baseClass, implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -818,7 +836,7 @@ private ClassDefinition CreateComputerDefinition (ClassDefinition baseClass)
       return computer;
     }
 
-    private ClassDefinition CreateClassWithRelatedClassIDColumnAndNoInheritanceDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateClassWithRelatedClassIDColumnAndNoInheritanceDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition classDefinition =
           CreateClassDefinition(
@@ -826,7 +844,8 @@ private ClassDefinition CreateClassWithRelatedClassIDColumnAndNoInheritanceDefin
               "TableWithRelatedClassIDColumnAndNoInheritance",
               typeof(ClassWithRelatedClassIDColumnAndNoInheritance),
               false,
-              baseClass);
+              baseClass,
+              implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -836,14 +855,15 @@ private ClassDefinition CreateClassWithRelatedClassIDColumnAndNoInheritanceDefin
       return classDefinition;
     }
 
-    private ClassDefinition CreateRelationTargetForPersistentMixinDefinition (ClassDefinition baseClass)
+    private ClassDefinition CreateRelationTargetForPersistentMixinDefinition (ClassDefinition baseClass, params InterfaceDefinition[] implementedInterfaces)
     {
       ClassDefinition relationTargetForPersistentMixinDefinition = CreateClassDefinition(
           "RelationTargetForPersistentMixin",
           "MixedDomains_RelationTarget",
           typeof(RelationTargetForPersistentMixin),
           false,
-          baseClass);
+          baseClass,
+          implementedInterfaces);
 
       var properties = new List<PropertyDefinition>();
       properties.Add(
@@ -873,6 +893,7 @@ private ClassDefinition CreateClassDefinition (
         Type classType,
         bool isAbstract,
         ClassDefinition baseClass,
+        IEnumerable<InterfaceDefinition> implementedInterfaces,
         params Type[] persistentMixins)
     {
       // Don't use ClassDefinitionObjectMother: since this configuration is compared with the actual configuration, we must exactly define 
@@ -882,6 +903,7 @@ private ClassDefinition CreateClassDefinition (
           classType,
           isAbstract,
           baseClass,
+          implementedInterfaces,
           null,
           DefaultStorageClass.Persistent,
           new PersistentMixinFinderStub(classType, persistentMixins),
@@ -895,6 +917,7 @@ private ClassDefinition CreateClassDefinitionForNonPersistentProvider (
         Type classType,
         bool isAbstract,
         ClassDefinition baseClass,
+        IEnumerable<InterfaceDefinition> implementedInterfaces,
         params Type[] persistentMixins)
     {
       // Don't use ClassDefinitionObjectMother: since this configuration is compared with the actual configuration, we must exactly define 
@@ -904,6 +927,7 @@ private ClassDefinition CreateClassDefinitionForNonPersistentProvider (
           classType,
           isAbstract,
           baseClass,
+          implementedInterfaces,
           null,
           DefaultStorageClass.Transaction,
           new PersistentMixinFinderStub(classType, persistentMixins),
@@ -1007,7 +1031,7 @@ private void CalculateAndSetRelationEndPointDefinitions (ICollection<RelationDef
       var relationsByClass = (from relationDefinition in relationDefinitions
                               from endPoint in relationDefinition.EndPointDefinitions
                               where !endPoint.IsAnonymous
-                              group endPoint by endPoint.ClassDefinition)
+                              group endPoint by endPoint.TypeDefinition)
                              .ToDictionary(grouping => grouping.Key, grouping => (IEnumerable<IRelationEndPointDefinition>)grouping);
 
       foreach (var classDefinition in _typeDefinitions.Values)
@@ -1048,12 +1072,12 @@ private RelationDefinition CreateCustomerToOrderRelationDefinition ()
 
     private RelationDefinition CreateOrderToOrderTicketRelationDefinition ()
     {
-      ClassDefinition orderClass = _typeDefinitions[typeof(Order)];
+      var orderClass = _typeDefinitions[typeof(Order)];
       VirtualObjectRelationEndPointDefinition endPoint1 =
           VirtualObjectRelationEndPointDefinitionFactory.Create(
               orderClass, "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.OrderTicket", true, typeof(OrderTicket));
 
-      ClassDefinition orderTicketClass = _typeDefinitions[typeof(OrderTicket)];
+      var orderTicketClass = _typeDefinitions[typeof(OrderTicket)];
       RelationEndPointDefinition endPoint2 = new RelationEndPointDefinition(
           orderTicketClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.OrderTicket.Order"], true);
 
@@ -1067,7 +1091,7 @@ private RelationDefinition CreateOrderToOrderTicketRelationDefinition ()
 
     private RelationDefinition CreateOrderToOrderItemRelationDefinition ()
     {
-      ClassDefinition orderClass = _typeDefinitions[typeof(Order)];
+      var orderClass = _typeDefinitions[typeof(Order)];
       DomainObjectCollectionRelationEndPointDefinition endPoint1 =
           DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
               orderClass,
@@ -1075,7 +1099,7 @@ private RelationDefinition CreateOrderToOrderItemRelationDefinition ()
               true,
               typeof(ObjectList<OrderItem>));
 
-      ClassDefinition orderItemClass = _typeDefinitions[typeof(OrderItem)];
+      var orderItemClass = _typeDefinitions[typeof(OrderItem)];
       RelationEndPointDefinition endPoint2 = new RelationEndPointDefinition(
           orderItemClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.OrderItem.Order"], true);
 
@@ -1177,13 +1201,13 @@ private RelationDefinition CreatePersonToProductReviewRelationDefinition ()
 
     private RelationDefinition CreateCompanyToCeoRelationDefinition ()
     {
-      ClassDefinition companyClass = _typeDefinitions[typeof(Company)];
+      var companyClass = _typeDefinitions[typeof(Company)];
 
       VirtualObjectRelationEndPointDefinition endPoint1 =
           VirtualObjectRelationEndPointDefinitionFactory.Create(
               companyClass, "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Company.Ceo", true, typeof(Ceo));
 
-      ClassDefinition ceoClass = _typeDefinitions[typeof(Ceo)];
+      var ceoClass = _typeDefinitions[typeof(Ceo)];
 
       RelationEndPointDefinition endPoint2 = new RelationEndPointDefinition(
           ceoClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Ceo.Company"], true);
@@ -1197,11 +1221,11 @@ private RelationDefinition CreateCompanyToCeoRelationDefinition ()
 
     private RelationDefinition CreatePartnerToPersonRelationDefinition ()
     {
-      ClassDefinition partnerClass = _typeDefinitions[typeof(Partner)];
+      var partnerClass = _typeDefinitions[typeof(Partner)];
       RelationEndPointDefinition endPoint1 = new RelationEndPointDefinition(
           partnerClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Partner.ContactPerson"], true);
 
-      ClassDefinition personClass = _typeDefinitions[typeof(Person)];
+      var personClass = _typeDefinitions[typeof(Person)];
       VirtualObjectRelationEndPointDefinition endPoint2 =
           VirtualObjectRelationEndPointDefinitionFactory.Create(
               personClass,
@@ -1219,7 +1243,7 @@ private RelationDefinition CreatePartnerToPersonRelationDefinition ()
 
     private RelationDefinition CreateParentClientToChildClientRelationDefinition ()
     {
-      ClassDefinition clientClass = _typeDefinitions[typeof(Client)];
+      var clientClass = _typeDefinitions[typeof(Client)];
 
       AnonymousRelationEndPointDefinition endPoint1 = new AnonymousRelationEndPointDefinition(clientClass);
       RelationEndPointDefinition endPoint2 =
@@ -1233,8 +1257,8 @@ private RelationDefinition CreateParentClientToChildClientRelationDefinition ()
 
     private RelationDefinition CreateClientToLocationRelationDefinition ()
     {
-      ClassDefinition clientClass = _typeDefinitions[typeof(Client)];
-      ClassDefinition locationClass = _typeDefinitions[typeof(Location)];
+      var clientClass = _typeDefinitions[typeof(Client)];
+      var locationClass = _typeDefinitions[typeof(Location)];
 
       AnonymousRelationEndPointDefinition endPoint1 = new AnonymousRelationEndPointDefinition(clientClass);
 
@@ -1249,11 +1273,11 @@ private RelationDefinition CreateClientToLocationRelationDefinition ()
 
     private RelationDefinition CreateFolderToFileSystemItemRelationDefinition ()
     {
-      ClassDefinition fileSystemItemClass = _typeDefinitions[typeof(FileSystemItem)];
+      var fileSystemItemClass = _typeDefinitions[typeof(FileSystemItem)];
       RelationEndPointDefinition endPoint1 = new RelationEndPointDefinition(
           fileSystemItemClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.FileSystemItem.ParentFolder"], false);
 
-      ClassDefinition folderClass = _typeDefinitions[typeof(Folder)];
+      var folderClass = _typeDefinitions[typeof(Folder)];
       DomainObjectCollectionRelationEndPointDefinition endPoint2 =
           DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
               folderClass,
@@ -1271,8 +1295,8 @@ private RelationDefinition CreateFolderToFileSystemItemRelationDefinition ()
 
     private RelationDefinition CreateCompanyToClassWithOptionalOneToOneRelationAndOppositeDerivedClassRelationDefinition ()
     {
-      ClassDefinition companyClass = _typeDefinitions[typeof(Company)];
-      ClassDefinition classWithOptionalOneToOneRelationAndOppositeDerivedClass =
+      var companyClass = _typeDefinitions[typeof(Company)];
+      var classWithOptionalOneToOneRelationAndOppositeDerivedClass =
           _typeDefinitions[typeof(ClassWithOptionalOneToOneRelationAndOppositeDerivedClass)];
 
       AnonymousRelationEndPointDefinition endPoint1 = new AnonymousRelationEndPointDefinition(companyClass);
@@ -1294,7 +1318,7 @@ private RelationDefinition CreateCompanyToClassWithOptionalOneToOneRelationAndOp
 
     private RelationDefinition CreateClassWithGuidKeyToClassWithValidRelationsOptional ()
     {
-      ClassDefinition classWithGuidKey = _typeDefinitions[typeof(ClassWithGuidKey)];
+      var classWithGuidKey = _typeDefinitions[typeof(ClassWithGuidKey)];
       VirtualObjectRelationEndPointDefinition endPoint1 =
           VirtualObjectRelationEndPointDefinitionFactory.Create(
               classWithGuidKey,
@@ -1302,7 +1326,7 @@ private RelationDefinition CreateClassWithGuidKeyToClassWithValidRelationsOption
               false,
               typeof(ClassWithValidRelations));
 
-      ClassDefinition classWithValidRelations = _typeDefinitions[typeof(ClassWithValidRelations)];
+      var classWithValidRelations = _typeDefinitions[typeof(ClassWithValidRelations)];
       RelationEndPointDefinition endPoint2 = new RelationEndPointDefinition(
           classWithValidRelations["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.ClassWithValidRelations.ClassWithGuidKeyOptional"], false);
 
@@ -1319,7 +1343,7 @@ private RelationDefinition CreateClassWithGuidKeyToClassWithValidRelationsOption
 
     private RelationDefinition CreateClassWithGuidKeyToClassWithValidRelationsNonOptional ()
     {
-      ClassDefinition classWithGuidKey = _typeDefinitions[typeof(ClassWithGuidKey)];
+      var classWithGuidKey = _typeDefinitions[typeof(ClassWithGuidKey)];
       VirtualObjectRelationEndPointDefinition endPoint1 =
           VirtualObjectRelationEndPointDefinitionFactory.Create(
               classWithGuidKey,
@@ -1327,7 +1351,7 @@ private RelationDefinition CreateClassWithGuidKeyToClassWithValidRelationsNonOpt
               true,
               typeof(ClassWithValidRelations));
 
-      ClassDefinition classWithValidRelations = _typeDefinitions[typeof(ClassWithValidRelations)];
+      var classWithValidRelations = _typeDefinitions[typeof(ClassWithValidRelations)];
       RelationEndPointDefinition endPoint2 = new RelationEndPointDefinition(
           classWithValidRelations["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.ClassWithValidRelations.ClassWithGuidKeyNonOptional"], true);
 
@@ -1344,7 +1368,7 @@ private RelationDefinition CreateClassWithGuidKeyToClassWithValidRelationsNonOpt
 
     private RelationDefinition CreateClassWithGuidKeyToClassWithInvalidRelation ()
     {
-      ClassDefinition classWithGuidKey = _typeDefinitions[typeof(ClassWithGuidKey)];
+      var classWithGuidKey = _typeDefinitions[typeof(ClassWithGuidKey)];
       VirtualObjectRelationEndPointDefinition endPoint1 =
           VirtualObjectRelationEndPointDefinitionFactory.Create(
               classWithGuidKey,
@@ -1352,7 +1376,7 @@ private RelationDefinition CreateClassWithGuidKeyToClassWithInvalidRelation ()
               false,
               typeof(ClassWithInvalidRelation));
 
-      ClassDefinition classWithInvalidRelation = _typeDefinitions[typeof(ClassWithInvalidRelation)];
+      var classWithInvalidRelation = _typeDefinitions[typeof(ClassWithInvalidRelation)];
       RelationEndPointDefinition endPoint2 = new RelationEndPointDefinition(
           classWithInvalidRelation["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.ClassWithInvalidRelation.ClassWithGuidKey"], false);
 
@@ -1369,7 +1393,7 @@ private RelationDefinition CreateClassWithGuidKeyToClassWithInvalidRelation ()
 
     private RelationDefinition CreateClassWithGuidKeyToClassWithRelatedClassIDColumnAndNoInheritanceRelation ()
     {
-      ClassDefinition classWithGuidKey = _typeDefinitions[typeof(ClassWithGuidKey)];
+      var classWithGuidKey = _typeDefinitions[typeof(ClassWithGuidKey)];
       VirtualObjectRelationEndPointDefinition endPoint1 =
           VirtualObjectRelationEndPointDefinitionFactory.Create(
               classWithGuidKey,
@@ -1377,7 +1401,7 @@ private RelationDefinition CreateClassWithGuidKeyToClassWithRelatedClassIDColumn
               false,
               typeof(ClassWithRelatedClassIDColumnAndNoInheritance));
 
-      ClassDefinition classWithRelatedClassIDColumnAndNoInheritance = _typeDefinitions[typeof(ClassWithRelatedClassIDColumnAndNoInheritance)];
+      var classWithRelatedClassIDColumnAndNoInheritance = _typeDefinitions[typeof(ClassWithRelatedClassIDColumnAndNoInheritance)];
       RelationEndPointDefinition endPoint2 = new RelationEndPointDefinition(
           classWithRelatedClassIDColumnAndNoInheritance[
           "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.ClassWithRelatedClassIDColumnAndNoInheritance.ClassWithGuidKey"],
@@ -1396,7 +1420,7 @@ private RelationDefinition CreateClassWithGuidKeyToClassWithRelatedClassIDColumn
 
     private RelationDefinition CreateIndustrialSectorToCompanyRelationDefinition ()
     {
-      ClassDefinition industrialSectorClass = _typeDefinitions[typeof(IndustrialSector)];
+      var industrialSectorClass = _typeDefinitions[typeof(IndustrialSector)];
 
       DomainObjectCollectionRelationEndPointDefinition endPoint1 =
           DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
@@ -1405,7 +1429,7 @@ private RelationDefinition CreateIndustrialSectorToCompanyRelationDefinition ()
               true,
               typeof(ObjectList<Company>));
 
-      ClassDefinition companyClass = _typeDefinitions[typeof(Company)];
+      var companyClass = _typeDefinitions[typeof(Company)];
 
       RelationEndPointDefinition endPoint2 = new RelationEndPointDefinition(
           companyClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Company.IndustrialSector"], false);
@@ -1421,7 +1445,7 @@ private RelationDefinition CreateIndustrialSectorToCompanyRelationDefinition ()
 
     private RelationDefinition CreateSupervisorToSubordinateRelationDefinition ()
     {
-      ClassDefinition employeeClass = _typeDefinitions[typeof(Employee)];
+      var employeeClass = _typeDefinitions[typeof(Employee)];
 
       DomainObjectCollectionRelationEndPointDefinition endPoint1 =
           DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
@@ -1443,13 +1467,13 @@ private RelationDefinition CreateSupervisorToSubordinateRelationDefinition ()
 
     private RelationDefinition CreateEmployeeToComputerRelationDefinition ()
     {
-      ClassDefinition employeeClass = _typeDefinitions[typeof(Employee)];
+      var employeeClass = _typeDefinitions[typeof(Employee)];
 
       VirtualObjectRelationEndPointDefinition endPoint1 =
           VirtualObjectRelationEndPointDefinitionFactory.Create(
               employeeClass, "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Employee.Computer", false, typeof(Computer));
 
-      ClassDefinition computerClass = _typeDefinitions[typeof(Computer)];
+      var computerClass = _typeDefinitions[typeof(Computer)];
 
       RelationEndPointDefinition endPoint2 = new RelationEndPointDefinition(
           computerClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Computer.Employee"], false);
@@ -1464,13 +1488,13 @@ private RelationDefinition CreateEmployeeToComputerRelationDefinition ()
 
     private RelationDefinition CreateTargetClassForPersistentMixinMixedUnidirectionalRelationDefinition ()
     {
-      ClassDefinition mixedClass = _typeDefinitions[typeof(TargetClassForPersistentMixin)];
+      var mixedClass = _typeDefinitions[typeof(TargetClassForPersistentMixin)];
 
       RelationEndPointDefinition endPoint1 = new RelationEndPointDefinition(
           mixedClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.MixedMapping.MixinAddingPersistentProperties.UnidirectionalRelationProperty"],
           false);
 
-      ClassDefinition relatedClass = _typeDefinitions[typeof(RelationTargetForPersistentMixin)];
+      var relatedClass = _typeDefinitions[typeof(RelationTargetForPersistentMixin)];
 
       AnonymousRelationEndPointDefinition endPoint2 = new AnonymousRelationEndPointDefinition(relatedClass);
 
@@ -1485,13 +1509,13 @@ private RelationDefinition CreateTargetClassForPersistentMixinMixedUnidirectiona
 
     private RelationDefinition CreateTargetClassForPersistentMixinMixedRelationPropertyRelationDefinition ()
     {
-      ClassDefinition mixedClass = _typeDefinitions[typeof(TargetClassForPersistentMixin)];
+      var mixedClass = _typeDefinitions[typeof(TargetClassForPersistentMixin)];
 
       RelationEndPointDefinition endPoint1 = new RelationEndPointDefinition(
           mixedClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.MixedMapping.MixinAddingPersistentProperties.RelationProperty"],
           false);
 
-      ClassDefinition relatedClass = _typeDefinitions[typeof(RelationTargetForPersistentMixin)];
+      var relatedClass = _typeDefinitions[typeof(RelationTargetForPersistentMixin)];
 
       var endPoint2 = VirtualObjectRelationEndPointDefinitionFactory.Create(
           relatedClass,
@@ -1511,7 +1535,7 @@ private RelationDefinition CreateTargetClassForPersistentMixinMixedRelationPrope
 
     private RelationDefinition CreateTargetClassForPersistentMixinMixedVirtualRelationPropertyRelationDefinition ()
     {
-      ClassDefinition mixedClass = _typeDefinitions[typeof(TargetClassForPersistentMixin)];
+      var mixedClass = _typeDefinitions[typeof(TargetClassForPersistentMixin)];
 
       var endPoint1 = VirtualObjectRelationEndPointDefinitionFactory.Create(
           mixedClass,
@@ -1519,7 +1543,7 @@ private RelationDefinition CreateTargetClassForPersistentMixinMixedVirtualRelati
           false,
           typeof(RelationTargetForPersistentMixin));
 
-      ClassDefinition relatedClass = _typeDefinitions[typeof(RelationTargetForPersistentMixin)];
+      var relatedClass = _typeDefinitions[typeof(RelationTargetForPersistentMixin)];
 
       RelationEndPointDefinition endPoint2 = new RelationEndPointDefinition(
           relatedClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.MixedMapping.RelationTargetForPersistentMixin.RelationProperty2"],
@@ -1537,7 +1561,7 @@ private RelationDefinition CreateTargetClassForPersistentMixinMixedVirtualRelati
 
     private RelationDefinition CreateTargetClassForPersistentMixinMixedCollectionProperty1SideCreateTargetClassForPersistentMixinMixedCollectionPropertyRelationDefinition ()
     {
-      ClassDefinition mixedClass = _typeDefinitions[typeof(TargetClassForPersistentMixin)];
+      var mixedClass = _typeDefinitions[typeof(TargetClassForPersistentMixin)];
 
       var endPoint1 = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
           mixedClass,
@@ -1545,7 +1569,7 @@ private RelationDefinition CreateTargetClassForPersistentMixinMixedCollectionPro
           false,
           typeof(ObjectList<RelationTargetForPersistentMixin>));
 
-      ClassDefinition relatedClass = _typeDefinitions[typeof(RelationTargetForPersistentMixin)];
+      var relatedClass = _typeDefinitions[typeof(RelationTargetForPersistentMixin)];
 
       RelationEndPointDefinition endPoint2 = new RelationEndPointDefinition(
           relatedClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.MixedMapping.RelationTargetForPersistentMixin.RelationProperty3"],
@@ -1563,13 +1587,13 @@ private RelationDefinition CreateTargetClassForPersistentMixinMixedCollectionPro
 
     private RelationDefinition CreateTargetClassForPersistentMixinMixedCollectionPropertyNSideRelationDefinition ()
     {
-      ClassDefinition mixedClass = _typeDefinitions[typeof(TargetClassForPersistentMixin)];
+      var mixedClass = _typeDefinitions[typeof(TargetClassForPersistentMixin)];
 
       RelationEndPointDefinition endPoint1 = new RelationEndPointDefinition(
           mixedClass["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.MixedMapping.MixinAddingPersistentProperties.CollectionPropertyNSide"],
           false);
 
-      ClassDefinition relatedClass = _typeDefinitions[typeof(RelationTargetForPersistentMixin)];
+      var relatedClass = _typeDefinitions[typeof(RelationTargetForPersistentMixin)];
 
       var endPoint2 = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
           relatedClass,
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/InlineTypeDefinitionVisitorTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/InlineTypeDefinitionVisitorTest.cs
new file mode 100644
index 0000000000..7c96dfccb6
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/InlineTypeDefinitionVisitorTest.cs
@@ -0,0 +1,121 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using Moq;
+using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping
+{
+  [TestFixture]
+  public class InlineTypeDefinitionVisitorTest
+  {
+    public interface IVisitorCallReceiver<out T>
+    {
+      T HandleClassDefinition (ClassDefinition classDefinition);
+
+      T HandleInterfaceDefinition (InterfaceDefinition interfaceDefinition);
+    }
+
+    public interface IVisitorCallReceiver
+    {
+      void HandleClassDefinition (ClassDefinition classDefinition);
+
+      void HandleInterfaceDefinition (InterfaceDefinition interfaceDefinition);
+    }
+
+    private Mock<IVisitorCallReceiver<string>> _nonVoidReceiverMock;
+    private Mock<IVisitorCallReceiver> _voidReceiverMock;
+
+    [SetUp]
+    public void SetUp ()
+    {
+      _nonVoidReceiverMock = new Mock<IVisitorCallReceiver<string>>(MockBehavior.Strict);
+      _voidReceiverMock = new Mock<IVisitorCallReceiver>(MockBehavior.Strict);
+    }
+
+    [Test]
+    public void Visit_WithResult_ClassDefinition ()
+    {
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
+      _nonVoidReceiverMock
+          .Setup(_ => _.HandleClassDefinition(classDefinition))
+          .Returns("test")
+          .Verifiable();
+
+      Assert.That(ExecuteNonVoidVisit(classDefinition), Is.EqualTo("test"));
+
+      _nonVoidReceiverMock.Verify();
+    }
+
+    [Test]
+    public void Visit_WithResult_InterfaceDefinition ()
+    {
+      var interfaceDefinition = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      _nonVoidReceiverMock
+          .Setup(_ => _.HandleInterfaceDefinition(interfaceDefinition))
+          .Returns("test")
+          .Verifiable();
+
+      Assert.That(ExecuteNonVoidVisit(interfaceDefinition), Is.EqualTo("test"));
+
+      _nonVoidReceiverMock.Verify();
+    }
+
+    [Test]
+    public void Visit_WithoutResult_ClassDefinition ()
+    {
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
+      _voidReceiverMock
+          .Setup(_ => _.HandleClassDefinition(classDefinition))
+          .Verifiable();
+
+      ExecuteVoidVisit(classDefinition);
+
+      _voidReceiverMock.Verify();
+    }
+
+    [Test]
+    public void Visit_WithoutResult_InterfaceDefinition ()
+    {
+      var classDefinition = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      _voidReceiverMock
+          .Setup(_ => _.HandleInterfaceDefinition(classDefinition))
+          .Verifiable();
+
+      ExecuteVoidVisit(classDefinition);
+
+      _voidReceiverMock.Verify();
+    }
+
+    private string ExecuteNonVoidVisit (TypeDefinition typeDefinition)
+    {
+      return InlineTypeDefinitionVisitor.Visit<string>(
+          typeDefinition,
+          _nonVoidReceiverMock.Object.HandleClassDefinition,
+          _nonVoidReceiverMock.Object.HandleInterfaceDefinition);
+    }
+
+    private void ExecuteVoidVisit (TypeDefinition typeDefinition)
+    {
+      InlineTypeDefinitionVisitor.Visit(
+          typeDefinition,
+          _voidReceiverMock.Object.HandleClassDefinition,
+          _voidReceiverMock.Object.HandleInterfaceDefinition);
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/InlineTypeDefinitionWalkerTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/InlineTypeDefinitionWalkerTest.cs
new file mode 100644
index 0000000000..8dfc5b68fc
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/InlineTypeDefinitionWalkerTest.cs
@@ -0,0 +1,124 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using Moq;
+using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping
+{
+  [TestFixture]
+  public class InlineTypeDefinitionWalkerTest
+  {
+    private Mock<Action<ClassDefinition>> _classDefinitionActionMock;
+    private Mock<Action<InterfaceDefinition>> _interfaceDefinitionActionMock;
+    private Mock<Func<ClassDefinition, string>> _classDefinitionFuncMock;
+    private Mock<Func<InterfaceDefinition, string>> _interfaceDefinitionFuncMock;
+
+    [SetUp]
+    public void SetUp ()
+    {
+      _classDefinitionActionMock = new Mock<Action<ClassDefinition>>();
+      _interfaceDefinitionActionMock = new Mock<Action<InterfaceDefinition>>();
+      _classDefinitionFuncMock = new Mock<Func<ClassDefinition, string>>();
+      _interfaceDefinitionFuncMock = new Mock<Func<InterfaceDefinition, string>>();
+    }
+
+    [Test]
+    public void WalkAncestors_WithoutResult ()
+    {
+      var (iPerson, person) = CreateTestDomain();
+
+      _classDefinitionActionMock.Setup(_ => _(person));
+      _interfaceDefinitionActionMock.Setup(_ => _(iPerson));
+
+      InlineTypeDefinitionWalker.WalkAncestors(
+          person,
+          _classDefinitionActionMock.Object,
+          _interfaceDefinitionActionMock.Object);
+
+      _classDefinitionActionMock.Verify(_ => _(person), Times.Once);
+      _interfaceDefinitionActionMock.Verify(_ => _(iPerson), Times.Once);
+    }
+
+    [Test]
+    public void WalkWalkAncestors_WithResult ()
+    {
+      var (iPerson, person) = CreateTestDomain();
+
+      _classDefinitionFuncMock.Setup(_ => _(person)).Returns((string)null);
+      _interfaceDefinitionFuncMock.Setup(_ => _(iPerson)).Returns("result");
+
+      var result = InlineTypeDefinitionWalker.WalkAncestors(
+          person,
+          _classDefinitionFuncMock.Object,
+          _interfaceDefinitionFuncMock.Object,
+          match: value => value != null);
+      Assert.That(result, Is.EqualTo("result"));
+
+      _classDefinitionFuncMock.Verify(_ => _(person), Times.Once);
+      _interfaceDefinitionFuncMock.Verify(_ => _(iPerson), Times.Once);
+    }
+
+    [Test]
+    public void WalkDescendents_WithoutResult ()
+    {
+      var (iPerson, person) = CreateTestDomain();
+
+      _classDefinitionActionMock.Setup(_ => _(person));
+      _interfaceDefinitionActionMock.Setup(_ => _(iPerson));
+
+      InlineTypeDefinitionWalker.WalkDescendants(
+          iPerson,
+          _classDefinitionActionMock.Object,
+          _interfaceDefinitionActionMock.Object);
+
+      _classDefinitionActionMock.Verify(_ => _(person), Times.Once);
+      _interfaceDefinitionActionMock.Verify(_ => _(iPerson), Times.Once);
+    }
+
+    [Test]
+    public void WalkDescendents_WithResult ()
+    {
+      var (iPerson, person) = CreateTestDomain();
+
+      _classDefinitionFuncMock.Setup(_ => _(person)).Returns("result");
+      _interfaceDefinitionFuncMock.Setup(_ => _(iPerson)).Returns((string)null);
+
+      var result = InlineTypeDefinitionWalker.WalkDescendants(
+          iPerson,
+          _classDefinitionFuncMock.Object,
+          _interfaceDefinitionFuncMock.Object,
+          value => value != null);
+      Assert.That(result, Is.EqualTo("result"));
+
+      _classDefinitionFuncMock.Verify(_ => _(person), Times.Once);
+      _interfaceDefinitionFuncMock.Verify(_ => _(iPerson), Times.Once);
+    }
+
+    private static (InterfaceDefinition iPerson, ClassDefinition person) CreateTestDomain ()
+    {
+      var iPerson = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      var person = ClassDefinitionObjectMother.CreateClassDefinition(implementedInterfaces: new[] { iPerson });
+      iPerson.SetImplementingClasses(new[] { person });
+      iPerson.SetExtendingInterfaces(Array.Empty<InterfaceDefinition>());
+      person.SetDerivedClasses(Array.Empty<ClassDefinition>());
+
+      return (iPerson, person);
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/InterfaceDefinitionObjectMother.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/InterfaceDefinitionObjectMother.cs
new file mode 100644
index 0000000000..9a42d3e566
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/InterfaceDefinitionObjectMother.cs
@@ -0,0 +1,60 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using System.Collections.Generic;
+using Remotion.Data.DomainObjects.Mapping;
+using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping
+{
+  public static class InterfaceDefinitionObjectMother
+  {
+    public static InterfaceDefinition CreateInterfaceDefinition (
+        Type type = null,
+        IEnumerable<InterfaceDefinition> extendedInterfaces = null,
+        Type storageGroupType = null,
+        DefaultStorageClass? defaultStorageClass = null)
+    {
+      type ??= typeof(IOrder);
+      extendedInterfaces ??= Array.Empty<InterfaceDefinition>();
+      defaultStorageClass ??= DefaultStorageClass.Persistent;
+
+      return new InterfaceDefinition(
+          type,
+          extendedInterfaces,
+          storageGroupType,
+          defaultStorageClass.Value);
+    }
+
+    public static InterfaceDefinition CreateInterfaceDefinitionWithDefaultProperties (
+        Type type = null,
+        IEnumerable<InterfaceDefinition> extendedInterfaces = null,
+        Type storageGroupType = null,
+        DefaultStorageClass? defaultStorageClass = null)
+    {
+      var interfaceDefinition = CreateInterfaceDefinition(type, extendedInterfaces, storageGroupType, defaultStorageClass);
+
+      interfaceDefinition.SetStorageEntity(new FakeStorageEntityDefinition(new UnitTestStorageProviderStubDefinition("stub"), "stub"));
+      interfaceDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
+      interfaceDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+      interfaceDefinition.SetExtendingInterfaces(Array.Empty<InterfaceDefinition>());
+      interfaceDefinition.SetImplementingClasses(Array.Empty<ClassDefinition>());
+
+      return interfaceDefinition;
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/InterfaceDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/InterfaceDefinitionTest.cs
new file mode 100644
index 0000000000..4ec6cd9647
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/InterfaceDefinitionTest.cs
@@ -0,0 +1,329 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using System.Linq;
+using Moq;
+using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
+using Remotion.Reflection;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping
+{
+  [TestFixture]
+  public class InterfaceDefinitionTest
+  {
+    private interface IDomainBase
+    {
+    }
+
+    private interface IPerson : IDomainBase
+    {
+    }
+
+    private interface ICustomer : IPerson
+    {
+    }
+
+    private interface IOrganizationalUnit : IDomainBase
+    {
+    }
+
+    private UnitTestStorageProviderStubDefinition _storageProviderDefinition;
+
+    private InterfaceDefinition _domainBaseInterface;
+    private InterfaceDefinition _personInterface;
+    private InterfaceDefinition _customerInterface;
+    private InterfaceDefinition _organizationalUnitInterface;
+
+    [SetUp]
+    public void SetUp ()
+    {
+      _storageProviderDefinition = new UnitTestStorageProviderStubDefinition("DefaultStorageProvider");
+
+      _domainBaseInterface = InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties(typeof(IDomainBase));
+      _personInterface = InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties(typeof(IPerson), extendedInterfaces: new[] { _domainBaseInterface });
+      _customerInterface = InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties(typeof(ICustomer), extendedInterfaces: new[] { _personInterface });
+      _organizationalUnitInterface = InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties(
+          typeof(IOrganizationalUnit),
+          extendedInterfaces: new[] { _domainBaseInterface });
+
+      _domainBaseInterface.SetExtendingInterfaces(new[] { _personInterface, _organizationalUnitInterface });
+      _personInterface.SetExtendingInterfaces(new[] { _customerInterface });
+    }
+
+    [Test]
+    public void Initialize ()
+    {
+      var actual = new InterfaceDefinition(
+          typeof(IDomainBase),
+          Array.Empty<InterfaceDefinition>(),
+          null,
+          DefaultStorageClass.Transaction);
+
+      Assert.That(actual.Type, Is.SameAs(typeof(IDomainBase)));
+      Assert.That(actual.ExtendedInterfaces, Is.Empty);
+      Assert.That(actual.DefaultStorageClass, Is.EqualTo(DefaultStorageClass.Transaction));
+
+      Assert.That(actual.HasStorageEntityDefinitionBeenSet, Is.False);
+      Assert.That(
+          () => actual.StorageEntityDefinition,
+          Throws.InvalidOperationException
+              .With.Message.EqualTo(
+                  "StorageEntityDefinition has not been set for type 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+IDomainBase'."));
+
+      Assert.That(
+          () => actual.ImplementingClasses,
+          Throws.InvalidOperationException
+              .With.Message.EqualTo(
+                  "No implementing classes have been set for interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+IDomainBase'."));
+      Assert.That(
+          () => actual.ExtendingInterfaces,
+          Throws.InvalidOperationException
+              .With.Message.EqualTo(
+                  "No extending interfaces have been set for interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+IDomainBase'."));
+
+      Assert.That(actual.IsReadOnly, Is.False);
+    }
+
+    [Test]
+    public void IsPartOfInheritanceHierarchy ()
+    {
+      var detachedInterfaceDefinition = TypeDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties();
+      var extendedInterfaceDefinition = InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties();
+      var extendingInterfaceDefinition = InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties(extendedInterfaces: new[] { extendedInterfaceDefinition });
+      var implementedInterfaceDefinition = InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties();
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(implementedInterfaces: new[] { implementedInterfaceDefinition });
+
+      extendedInterfaceDefinition.SetExtendingInterfaces(new[] { extendingInterfaceDefinition });
+      implementedInterfaceDefinition.SetImplementingClasses(new[] { classDefinition });
+
+      Assert.That(detachedInterfaceDefinition.IsPartOfInheritanceHierarchy, Is.False);
+      Assert.That(extendingInterfaceDefinition.IsPartOfInheritanceHierarchy, Is.True);
+      Assert.That(extendingInterfaceDefinition.IsPartOfInheritanceHierarchy, Is.True);
+      Assert.That(extendingInterfaceDefinition.IsPartOfInheritanceHierarchy, Is.True);
+    }
+
+    [Test]
+    public void SetImplementingClasses ()
+    {
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(implementedInterfaces: new[] { _domainBaseInterface });
+      _domainBaseInterface.SetImplementingClasses(new[] { classDefinition });
+
+      Assert.That(_domainBaseInterface.ImplementingClasses.Count, Is.EqualTo(1));
+      Assert.That(_domainBaseInterface.ImplementingClasses[0], Is.SameAs(classDefinition));
+    }
+
+    [Test]
+    public void SetImplementingClasses_ReadOnly_Throws ()
+    {
+      var interfaceDefinition = InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties(typeof(IDomainBase));
+      interfaceDefinition.SetReadOnly();
+
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
+      Assert.That(
+          () => interfaceDefinition.SetImplementingClasses(new[] { classDefinition }),
+          Throws.TypeOf<NotSupportedException>()
+              .With.Message.EqualTo(
+                  "Interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+IDomainBase' is read-only."));
+    }
+
+    [Test]
+    public void SetImplementingClasses_WithInvalidClassDefinition_Throws ()
+    {
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
+      Assert.That(
+          () => _domainBaseInterface.SetImplementingClasses(new[] { classDefinition }),
+          Throws.TypeOf<MappingException>()
+              .With.Message.EqualTo(
+                  "Interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+IDomainBase' "
+                  + "cannot be implemented by class 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order', "
+                  + "because 'IDomainBase' is not contained in the list of implemented interfaces on 'Order'."));
+    }
+
+    [Test]
+    public void SetExtendingInterfaces ()
+    {
+      _domainBaseInterface.SetExtendingInterfaces(new[] { _personInterface });
+
+      Assert.That(_domainBaseInterface.ExtendingInterfaces.Count, Is.EqualTo(1));
+      Assert.That(_domainBaseInterface.ExtendingInterfaces[0], Is.SameAs(_personInterface));
+    }
+
+    [Test]
+    public void SetExtendingInterfaces_ReadOnly_Throws ()
+    {
+      var interfaceDefinition = InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties(typeof(IDomainBase));
+      interfaceDefinition.SetReadOnly();
+
+      Assert.That(
+          () => interfaceDefinition.SetExtendingInterfaces(new[] { _personInterface }),
+          Throws.TypeOf<NotSupportedException>()
+              .With.Message.EqualTo(
+                  "Interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+IDomainBase' is read-only."));
+    }
+
+    [Test]
+    public void SetExtendingInterfaces_WithInvalidClassDefinition_Throws ()
+    {
+      var interfaceDefinition = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      Assert.That(
+          () => _domainBaseInterface.SetExtendingInterfaces(new[] { interfaceDefinition }),
+          Throws.TypeOf<MappingException>()
+              .With.Message.EqualTo(
+                  "Interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+IDomainBase' "
+                  + "cannot be extended by interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.IOrder', "
+                  + "because 'IDomainBase' is not contained in the list of extended interfaces on 'IOrder'."));
+    }
+
+    [Test]
+    public void Accept ()
+    {
+      var mock = new Mock<ITypeDefinitionVisitor>(MockBehavior.Strict);
+      mock.Setup(_ => _.VisitInterfaceDefinition(_domainBaseInterface)).Verifiable();
+      _domainBaseInterface.Accept(mock.Object);
+
+      mock.Verify();
+    }
+
+    [Test]
+    public void AcceptWithResult ()
+    {
+      var mock = new Mock<ITypeDefinitionVisitor<string>>();
+      mock.Setup(_ => _.VisitInterfaceDefinition(_domainBaseInterface)).Returns("asd");
+
+      Assert.That(_domainBaseInterface.Accept(mock.Object), Is.EqualTo("asd"));
+    }
+
+    [Test]
+    public void SetPropertyDefinitions_WithIncorrectParent_Throws ()
+    {
+      var customer = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(typeof(ICustomer));
+      var organizationalUnit = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(typeof(IOrganizationalUnit));
+
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(customer, "Name");
+      Assert.That(
+          () => organizationalUnit.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true)),
+          Throws.InstanceOf<MappingException>()
+              .With.Message.EqualTo(
+                  "Property 'Name' cannot be added to interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+IOrganizationalUnit', because it was initialized for "
+                  + "type 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+ICustomer'."));
+    }
+
+    [Test]
+    public void SetPropertyDefinitions_WithExistingProperty_Throws ()
+    {
+      var domainBase = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(typeof(IDomainBase));
+      domainBase.SetPropertyDefinitions(new PropertyDefinitionCollection());
+
+      var person = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(typeof(IPerson));
+      var personProperty = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(person, "Name");
+      person.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { personProperty }, true));
+
+      var customer = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(typeof(ICustomer), new[] { domainBase, person });
+      var customerProperty = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(customer, "Name");
+
+      Assert.That(
+          () => customer.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { customerProperty }, true)),
+          Throws.InstanceOf<MappingException>()
+              .With.Message.EqualTo(
+                  "Property 'Name' cannot be added to interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+ICustomer', because extended interface "
+                  + "'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+IPerson' already defines a property with the same name."));
+    }
+
+    [Test]
+    public void SetRelationEndPointDefinitions_WithIncorrectParent_Throws ()
+    {
+      var customer = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(typeof(ICustomer));
+      var organizationalUnit = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(typeof(IOrganizationalUnit));
+
+      var relationEndPointDefinition = new VirtualObjectRelationEndPointDefinition(customer, "Name", true, new NullPropertyInformation());
+      Assert.That(
+          () => organizationalUnit.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { relationEndPointDefinition }, true)),
+          Throws.InstanceOf<MappingException>()
+              .With.Message.EqualTo(
+                  "Relation end point for property 'Name' cannot be added to interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+IOrganizationalUnit', because it was initialized for "
+                  + "interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+ICustomer'."));
+    }
+
+    [Test]
+    public void SetRelationEndPointDefinitions_WithExistingProperty_Throws ()
+    {
+      var domainBase = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(typeof(IDomainBase));
+      domainBase.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+
+      var person = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(typeof(IPerson));
+      var personRelationEndPointDefinition = new VirtualObjectRelationEndPointDefinition(person, "Name", true, new NullPropertyInformation());
+      person.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { personRelationEndPointDefinition }, true));
+
+      var customer = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(typeof(ICustomer), new[] { domainBase, person });
+      var customerRelationEndPointDefinition = new VirtualObjectRelationEndPointDefinition(customer, "Name", true, new NullPropertyInformation());
+
+      Assert.That(
+          () => customer.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { customerRelationEndPointDefinition }, true)),
+          Throws.InstanceOf<MappingException>()
+              .With.Message.EqualTo(
+                  "Relation end point for property 'Name' cannot be added to interface 'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+ICustomer', because extended interface "
+                  + "'Remotion.Data.DomainObjects.UnitTests.Mapping.InterfaceDefinitionTest+IPerson' already defines a relation end point with the same property name."));
+    }
+
+    [Test]
+    public void SetReadOnly ()
+    {
+      var interfaceDefinition = InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties();
+      Assert.That(interfaceDefinition.IsReadOnly, Is.False);
+
+      interfaceDefinition.SetReadOnly();
+
+      Assert.That(interfaceDefinition.IsReadOnly, Is.True);
+    }
+
+    [Test]
+    public void SetReadOnly_WithUnsetImplementingClasses_Throws ()
+    {
+      var interfaceDefinition = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      Assert.That(
+          () => interfaceDefinition.SetReadOnly(),
+          Throws.InvalidOperationException
+              .With.Message.EqualTo("Cannot set the type definition read-only as the implementing classes are not set."));
+    }
+
+    [Test]
+    public void SetReadOnly_WithUnsetExtendingInterfaces_Throws ()
+    {
+      var interfaceDefinition = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      interfaceDefinition.SetImplementingClasses(Enumerable.Empty<ClassDefinition>());
+
+      Assert.That(
+          () => interfaceDefinition.SetReadOnly(),
+          Throws.InvalidOperationException
+              .With.Message.EqualTo("Cannot set the type definition read-only as the extending interfaces are not set."));
+    }
+
+    [Test]
+    public void IsAssignableFrom ()
+    {
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties(implementedInterfaces: new[] { _customerInterface });
+      _customerInterface.SetImplementingClasses(new[] { classDefinition });
+
+      Assert.That(_domainBaseInterface.IsAssignableFrom(_domainBaseInterface), Is.True);
+      Assert.That(_domainBaseInterface.IsAssignableFrom(classDefinition), Is.True);
+      Assert.That(_organizationalUnitInterface.IsAssignableFrom(classDefinition), Is.False);
+      Assert.That(_personInterface.IsAssignableFrom(_customerInterface), Is.True);
+      Assert.That(_personInterface.IsAssignableFrom(_organizationalUnitInterface), Is.False);
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/InvalidRelationEndPointDefinitionBaseTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/InvalidRelationEndPointDefinitionBaseTest.cs
index 30d99989e9..56b6a1e4b9 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/InvalidRelationEndPointDefinitionBaseTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/InvalidRelationEndPointDefinitionBaseTest.cs
@@ -27,26 +27,26 @@ public class InvalidRelationEndPointDefinitionBaseTest
   {
     private class TestableInvalidRelationEndPointDefinitionBase : InvalidRelationEndPointDefinitionBase
     {
-      public TestableInvalidRelationEndPointDefinitionBase (ClassDefinition classDefinition, string propertyName, Type propertyType)
-          : base(classDefinition, propertyName, propertyType)
+      public TestableInvalidRelationEndPointDefinitionBase (TypeDefinition typeDefinition, string propertyName, Type propertyType)
+          : base(typeDefinition, propertyName, propertyType)
       {
       }
     }
 
     private InvalidRelationEndPointDefinitionBase _invalidEndPointDefinition;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     [SetUp]
     public void SetUp ()
     {
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(Order));
-      _invalidEndPointDefinition = new TestableInvalidRelationEndPointDefinitionBase(_classDefinition, "TestProperty", typeof(string));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(Order));
+      _invalidEndPointDefinition = new TestableInvalidRelationEndPointDefinitionBase(_typeDefinition, "TestProperty", typeof(string));
     }
 
     [Test]
     public void Initialization ()
     {
-      Assert.That(_invalidEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(_invalidEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(_invalidEndPointDefinition.PropertyName, Is.EqualTo("TestProperty"));
       Assert.That(_invalidEndPointDefinition.PropertyInfo.DeclaringType, Is.SameAs(TypeAdapter.Create(typeof(Order))));
       Assert.That(_invalidEndPointDefinition.PropertyInfo.Name, Is.EqualTo("TestProperty"));
@@ -67,7 +67,7 @@ public void RelationDefinition_NotSet ()
     [Test]
     public void SetRelationDefinition ()
     {
-      var endPoint = new AnonymousRelationEndPointDefinition(_classDefinition);
+      var endPoint = new AnonymousRelationEndPointDefinition(_typeDefinition);
       var relationDefinition = new RelationDefinition("Test", endPoint, endPoint);
 
       _invalidEndPointDefinition.SetRelationDefinition(relationDefinition);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingConfigurationExtensionsTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingConfigurationExtensionsTest.cs
new file mode 100644
index 0000000000..867e41b967
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingConfigurationExtensionsTest.cs
@@ -0,0 +1,162 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using Moq;
+using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
+using Remotion.Development.NUnit.UnitTesting;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping
+{
+  [TestFixture]
+  public class MappingConfigurationExtensionsTest
+  {
+    private interface IDummyInterface
+    {
+    }
+
+    private class DummyClass
+    {
+    }
+
+    [Test]
+    public void GetTypeDefinition ()
+    {
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition();
+      var mappingConfigurationMock = new Mock<IMappingConfiguration>(MockBehavior.Strict);
+      mappingConfigurationMock.Setup(_ => _.GetTypeDefinition(typeof(IDummyInterface), It.IsAny<Func<Type, Exception>>())).Returns(typeDefinition);
+
+      var result = mappingConfigurationMock.Object.GetTypeDefinition(typeof(IDummyInterface));
+      Assert.That(result, Is.SameAs(typeDefinition));
+    }
+
+    [Test]
+    public void GetTypeDefinition_WithNonExistentType_Throws ()
+    {
+      Assert.That(
+          () => MappingConfiguration.Current.GetTypeDefinition(typeof(IDummyInterface)),
+          Throws.TypeOf<MappingException>()
+              .With.Message.EqualTo("Mapping does not contain type 'Remotion.Data.DomainObjects.UnitTests.Mapping.MappingConfigurationExtensionsTest+IDummyInterface'."));
+    }
+
+    [TestCase(true)]
+    [TestCase(false)]
+    [Test]
+    public void ContainsClassDefinition (bool value)
+    {
+      var mappingConfigurationMock = new Mock<IMappingConfiguration>(MockBehavior.Strict);
+      mappingConfigurationMock.Setup(_ => _.ContainsTypeDefinition(typeof(DummyClass)))
+          .Returns(value)
+          .Verifiable();
+
+      Assert.That(mappingConfigurationMock.Object.ContainsClassDefinition(typeof(DummyClass)), Is.EqualTo(value));
+      mappingConfigurationMock.Verify();
+    }
+
+    [Test]
+    public void ContainsClassDefinition_NonClassType_ReturnsFalse ()
+    {
+      var mappingConfigurationMock = new Mock<IMappingConfiguration>(MockBehavior.Strict);
+      Assert.That(mappingConfigurationMock.Object.ContainsClassDefinition(typeof(IDummyInterface)), Is.False);
+    }
+
+    [Test]
+    public void GetClassDefinition ()
+    {
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
+      var mappingConfigurationMock = new Mock<IMappingConfiguration>(MockBehavior.Strict);
+      mappingConfigurationMock
+          .Setup(_ => _.GetTypeDefinition(typeof(DummyClass), It.IsAny<Func<Type, Exception>>()))
+          .Returns(classDefinition);
+
+      var result = mappingConfigurationMock.Object.GetClassDefinition(typeof(DummyClass));
+      Assert.That(result, Is.SameAs(classDefinition));
+    }
+
+    [Test]
+    public void GetClassDefinition_WithNonClass_Throws ()
+    {
+      var mappingConfigurationMock = new Mock<IMappingConfiguration>(MockBehavior.Strict);
+
+      Assert.That(
+          () => mappingConfigurationMock.Object.GetClassDefinition(typeof(IDummyInterface)),
+          Throws.TypeOf<ArgumentException>()
+              .With.ArgumentExceptionMessageEqualTo(
+                  "The specified type 'Remotion.Data.DomainObjects.UnitTests.Mapping.MappingConfigurationExtensionsTest+IDummyInterface' must be a class.",
+                  "type"));
+    }
+
+    [Test]
+    public void GetClassDefinition_WithCustomExceptionFactory ()
+    {
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition();
+      var exceptionFactory = new Func<Type, Exception>(_ => new Exception());
+      var mappingConfigurationMock = new Mock<IMappingConfiguration>(MockBehavior.Strict);
+      mappingConfigurationMock
+          .Setup(_ => _.GetTypeDefinition(typeof(DummyClass), exceptionFactory))
+          .Returns(typeDefinition);
+
+      var result = mappingConfigurationMock.Object.GetClassDefinition(typeof(DummyClass), exceptionFactory);
+      Assert.That(result, Is.SameAs(typeDefinition));
+    }
+
+    [Test]
+    public void GetClassDefinition_WithCustomerExceptionFactoryAndNonClass_Throws ()
+    {
+      var exceptionFactoryMock = new Mock<Func<Type, Exception>>(MockBehavior.Strict);
+      var mappingConfigurationMock = new Mock<IMappingConfiguration>(MockBehavior.Strict);
+
+      Assert.That(
+          () => mappingConfigurationMock.Object.GetClassDefinition(typeof(IDummyInterface), exceptionFactoryMock.Object),
+          Throws.TypeOf<ArgumentException>()
+              .With.ArgumentExceptionMessageEqualTo(
+                  "The specified type 'Remotion.Data.DomainObjects.UnitTests.Mapping.MappingConfigurationExtensionsTest+IDummyInterface' must be a class.",
+                  "type"));
+    }
+
+    [Test]
+    public void GetClassDefinition_WithCustomerExceptionFactoryAndNonExistingClass_ThrowsExceptionFromFactory ()
+    {
+      var exception = new Exception("Test");
+      var exceptionFactory = new Func<Type, Exception>(_ => exception);
+
+      Assert.That(
+          Assert.Throws<Exception>(() => MappingConfiguration.Current.GetClassDefinition(typeof(DummyClass), exceptionFactory)),
+          Is.SameAs(exception));
+    }
+
+    [Test]
+    public void GetClassDefinition_WithClassID ()
+    {
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
+      var mappingConfigurationMock = new Mock<IMappingConfiguration>(MockBehavior.Strict);
+      mappingConfigurationMock.Setup(_ => _.GetClassDefinition("asdNonExistent", It.IsAny<Func<string, Exception>>())).Returns(classDefinition);
+
+      var result = mappingConfigurationMock.Object.GetClassDefinition("asdNonExistent");
+      Assert.That(result, Is.SameAs(classDefinition));
+    }
+
+    [Test]
+    public void GetClassDefinition_WithNonClassID_ThrowsExceptionFromFactory ()
+    {
+      Assert.That(
+          () => MappingConfiguration.Current.GetClassDefinition("asdNonExistent"),
+          Throws.TypeOf<MappingException>()
+              .With.Message.EqualTo("Mapping does not contain class 'asdNonExistent'."));
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingConfigurationTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingConfigurationTest.cs
index bb3c456fd9..6e1d36c236 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingConfigurationTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingConfigurationTest.cs
@@ -42,7 +42,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   [TestFixture]
   public class MappingConfigurationTest : MappingReflectionTestBase
   {
-    private ClassDefinition[] _emptyClassDefinitions;
+    private TypeDefinition[] _emptyClassDefinitions;
     private RelationDefinition[] _emptyRelationDefinitions;
     private Mock<IMappingLoader> _mockMappingLoader;
     private ReflectionBasedMemberInformationNameResolver _memberInformationNameResolver;
@@ -52,7 +52,7 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _emptyClassDefinitions = new ClassDefinition[0];
+      _emptyClassDefinitions = new TypeDefinition[0];
       _emptyRelationDefinitions = new RelationDefinition[0];
 
       _memberInformationNameResolver = new ReflectionBasedMemberInformationNameResolver();
@@ -65,7 +65,7 @@ public override void SetUp ()
     [Test]
     public void Initialize ()
     {
-      var typeDefinitions = new ClassDefinition[0];
+      var typeDefinitions = new TypeDefinition[0];
       var relationDefinitions = new RelationDefinition[0];
 
       StubMockMappingLoader(typeDefinitions, relationDefinitions);
@@ -101,13 +101,8 @@ public void SetCurrent ()
     [Test]
     public void GetTypeDefinitions ()
     {
-      var classDefinition1 = ClassDefinitionObjectMother.CreateClassDefinition("C1", typeof(RelationEndPointPropertyClass));
-      classDefinition1.SetPropertyDefinitions(new PropertyDefinitionCollection());
-      classDefinition1.SetDerivedClasses(Enumerable.Empty<ClassDefinition>());
-
-      var classDefinition2 = ClassDefinitionObjectMother.CreateClassDefinition("C2", typeof(RelationEndPointPropertyClass1));
-      classDefinition2.SetPropertyDefinitions(new PropertyDefinitionCollection());
-      classDefinition2.SetDerivedClasses(Enumerable.Empty<ClassDefinition>());
+      var classDefinition1 = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties("C1", typeof(RelationEndPointPropertyClass));
+      var classDefinition2 = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties("C2", typeof(RelationEndPointPropertyClass1));
 
       StubMockMappingLoader(new[] { classDefinition1, classDefinition2 }, _emptyRelationDefinitions);
       var persistenceModelLoaderStub = CreatePersistenceModelLoaderStub();
@@ -119,7 +114,7 @@ public void GetTypeDefinitions ()
     [Test]
     public void ContainsTypeDefinition_ValueFound ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass));
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixinsWithDefaultProperties(typeof(RelationEndPointPropertyClass));
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
       classDefinition.SetDerivedClasses(Enumerable.Empty<ClassDefinition>());
       StubMockMappingLoader(new[] { classDefinition }, _emptyRelationDefinitions);
@@ -142,7 +137,7 @@ public void ContainsTypeDefinition_ValueNotFound ()
     [Test]
     public void GetTypeDefinition_ValueFound ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass));
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixinsWithDefaultProperties(typeof(RelationEndPointPropertyClass));
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
       classDefinition.SetDerivedClasses(Enumerable.Empty<ClassDefinition>());
       StubMockMappingLoader(new[] { classDefinition }, _emptyRelationDefinitions);
@@ -162,7 +157,7 @@ public void GetTypeDefinition_ValueNotFound ()
       Assert.That(
           () => configuration.GetTypeDefinition(typeof(DomainObject)),
           Throws.Exception.TypeOf<MappingException>()
-              .And.Message.EqualTo(String.Format("Mapping does not contain class '{0}'.", typeof(DomainObject))));
+              .And.Message.EqualTo(String.Format("Mapping does not contain type '{0}'.", typeof(DomainObject))));
     }
 
     [Test]
@@ -181,7 +176,7 @@ public void GetTypeDefinition_ValueNotFound_CustomException ()
     [Test]
     public void ContainsClassDefinition_ValueFound ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass));
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixinsWithDefaultProperties(typeof(RelationEndPointPropertyClass));
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
       classDefinition.SetDerivedClasses(Enumerable.Empty<ClassDefinition>());
       StubMockMappingLoader(new[] { classDefinition }, _emptyRelationDefinitions);
@@ -204,7 +199,7 @@ public void ContainsClassDefinition_ValueNotFound ()
     [Test]
     public void GetClassDefinition_ValueFound ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass));
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixinsWithDefaultProperties(typeof(RelationEndPointPropertyClass));
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
       classDefinition.SetDerivedClasses(Enumerable.Empty<ClassDefinition>());
       StubMockMappingLoader(new[] { classDefinition }, _emptyRelationDefinitions);
@@ -253,7 +248,7 @@ public void PersistenceModelIsLoaded ()
       var persistenceModelLoaderMock = new Mock<IPersistenceModelLoader>(MockBehavior.Strict);
       persistenceModelLoaderMock
           .Setup(mock => mock.ApplyPersistenceModelToHierarchy(classDefinition))
-          .Callback((ClassDefinition classDefinition) => classDefinition.SetStorageEntity(TableDefinitionObjectMother.Create(TestDomainStorageProviderDefinition)))
+          .Callback((TypeDefinition classDefinition) => classDefinition.SetStorageEntity(TableDefinitionObjectMother.Create(TestDomainStorageProviderDefinition)))
           .Verifiable();
       persistenceModelLoaderMock
           .Setup(mock => mock.CreatePersistenceMappingValidator(classDefinition))
@@ -282,36 +277,39 @@ public void PersistenceModelIsLoaded_NoStorageEntityIsAppliedToTheRootClass ()
       Assert.That(
           () => mappingConfiguration.EnsureInitialized(),
           Throws.InvalidOperationException
-              .With.Message.EqualTo("The persistence model loader did not assign a storage entity to class 'Order'."));
+              .With.Message.EqualTo(
+                  "The persistence model loader did not assign a storage entity to type "
+                  + "'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order'."));
     }
 
     [Test]
     public void PersistenceModelIsLoaded_NoStoragePropertyIsAppliedToTheRootClassProperty ()
     {
       var fakeStorageEntityDefinition = _fakeStorageEntityDefinition;
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition("Order", typeof(Order));
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition, "Fake");
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition("Order", typeof(Order));
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(typeDefinition, "Fake");
       PrivateInvoke.SetNonPublicField(propertyDefinition, "_storagePropertyDefinition", null);
 
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
 
-      Assert.That(classDefinition.HasStorageEntityDefinitionBeenSet, Is.False);
+      Assert.That(typeDefinition.HasStorageEntityDefinitionBeenSet, Is.False);
       Assert.That(propertyDefinition.HasStoragePropertyDefinitionBeenSet, Is.False);
 
       var persistenceModelStub = new Mock<IPersistenceModelLoader>();
 
-      StubMockMappingLoader(new[] { classDefinition }, new RelationDefinition[0]);
+      StubMockMappingLoader(new[] { typeDefinition }, new RelationDefinition[0]);
 
       persistenceModelStub
-          .Setup(stub => stub.ApplyPersistenceModelToHierarchy(classDefinition))
-          .Callback((ClassDefinition classDefinition) => classDefinition.SetStorageEntity(fakeStorageEntityDefinition));
+          .Setup(stub => stub.ApplyPersistenceModelToHierarchy(typeDefinition))
+          .Callback((TypeDefinition classDefinition) => classDefinition.SetStorageEntity(fakeStorageEntityDefinition));
       var mappingConfiguration = new MappingConfiguration(_mockMappingLoader.Object, persistenceModelStub.Object);
 
       Assert.That(
           () => mappingConfiguration.EnsureInitialized(),
           Throws.InvalidOperationException
               .With.Message.EqualTo(
-                  "StoragePropertyDefinition has not been set for property 'Fake' of class 'Order'."));
+                  "StoragePropertyDefinition has not been set for property 'Fake' of type "
+                  + "'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order'."));
     }
 
     [Test]
@@ -335,22 +333,24 @@ public void PersistenceModelIsLoaded_NoStorageEntityIsAppliedToDerivedClass ()
 
       persistenceModelStub
           .Setup(stub => stub.ApplyPersistenceModelToHierarchy(companyClass))
-          .Callback((ClassDefinition classDefinition) => companyClass.SetStorageEntity(fakeStorageEntityDefinition));
+          .Callback((TypeDefinition classDefinition) => companyClass.SetStorageEntity(fakeStorageEntityDefinition));
       var mappingConfiguration = new MappingConfiguration(_mockMappingLoader.Object, persistenceModelStub.Object);
 
       Assert.That(
           () => mappingConfiguration.EnsureInitialized(),
           Throws.InvalidOperationException
-              .With.Message.EqualTo("The persistence model loader did not assign a storage entity to class 'Partner'."));
+              .With.Message.EqualTo(
+                  "The persistence model loader did not assign a storage entity to type "
+                  + "'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Partner'."));
     }
 
     [Test]
     public void ClassDefinitionsAreValidated ()
     {
       var type = typeof(GenericTypeDomainObject<string>);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
 
-      StubMockMappingLoaderWithValidation(new[] { classDefinition }, new RelationDefinition[0]);
+      StubMockMappingLoaderWithValidation(new[] { typeDefinition }, new RelationDefinition[0]);
       var mappingConfiguration = new MappingConfiguration(_mockMappingLoader.Object, new PersistenceModelLoader(StorageSettings));
 
       Assert.That(
@@ -365,19 +365,19 @@ public void ClassDefinitionsAreValidated ()
     [Test]
     public void PropertyDefinitionsAreValidated ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
       var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(
-          classDefinition, typeof(DerivedValidationDomainObjectClass), "PropertyWithStorageClassNone");
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+          typeDefinition, typeof(DerivedValidationDomainObjectClass), "PropertyWithStorageClassNone");
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
 
-      StubMockMappingLoaderWithValidation(new[] { classDefinition }, new RelationDefinition[0]);
+      StubMockMappingLoaderWithValidation(new[] { typeDefinition }, new RelationDefinition[0]);
       var mappingConfiguration = new MappingConfiguration(_mockMappingLoader.Object, new PersistenceModelLoader(StorageSettings));
 
       Assert.That(
           () => mappingConfiguration.EnsureInitialized(),
           Throws.InstanceOf<MappingException>()
               .With.Message.EqualTo(
-                  "Only StorageClass.Persistent and StorageClass.Transaction are supported for property 'PropertyWithStorageClassNone' of class "
+                  "Only StorageClass.Persistent and StorageClass.Transaction are supported for property 'PropertyWithStorageClassNone' of type "
                   + "'DerivedValidationDomainObjectClass'.\r\n\r\n"
                   + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.DerivedValidationDomainObjectClass\r\n"
                   + "Property: PropertyWithStorageClassNone"));
@@ -386,15 +386,15 @@ public void PropertyDefinitionsAreValidated ()
     [Test]
     public void RelationDefinitionsAreValidated ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass));
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass));
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
       var relationDefinition =
           FakeMappingConfiguration.Current.RelationDefinitions[
               "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order:"
               +"Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.Customer->"
               +"Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders"];
 
-      StubMockMappingLoaderWithValidation(new[] { classDefinition }, new[] { relationDefinition });
+      StubMockMappingLoaderWithValidation(new[] { typeDefinition }, new[] { relationDefinition });
       var mappingConfiguration = new MappingConfiguration(_mockMappingLoader.Object, new PersistenceModelLoader(StorageSettings));
 
       Assert.That(
@@ -441,16 +441,16 @@ public void PersistenceModelIsValidated_OverAllRootClasses ()
       var validatorMock1 = new Mock<IPersistenceMappingValidator>(MockBehavior.Strict);
       var validatorMock2 = new Mock<IPersistenceMappingValidator>(MockBehavior.Strict);
 
-      var rootClass1 = ClassDefinitionObjectMother.CreateClassDefinition_WithEmptyMembers_AndDerivedClasses("Order", typeof(Order));
-      var rootClass2 = ClassDefinitionObjectMother.CreateClassDefinition_WithEmptyMembers_AndDerivedClasses("OrderTicket", typeof(OrderTicket));
+      var rootClass1 = TypeDefinitionObjectMother.CreateClassDefinition_WithEmptyMembers_AndDerivedClasses("Order", typeof(Order));
+      var rootClass2 = TypeDefinitionObjectMother.CreateClassDefinition_WithEmptyMembers_AndDerivedClasses("OrderTicket", typeof(OrderTicket));
 
       persistenceModelLoaderMock
           .Setup(mock => mock.ApplyPersistenceModelToHierarchy(rootClass1))
-          .Callback((ClassDefinition classDefinition) => rootClass1.SetStorageEntity(_fakeStorageEntityDefinition))
+          .Callback((TypeDefinition classDefinition) => rootClass1.SetStorageEntity(_fakeStorageEntityDefinition))
           .Verifiable();
       persistenceModelLoaderMock
           .Setup(mock => mock.ApplyPersistenceModelToHierarchy(rootClass2))
-          .Callback((ClassDefinition classDefinition) => rootClass2.SetStorageEntity(_fakeStorageEntityDefinition))
+          .Callback((TypeDefinition classDefinition) => rootClass2.SetStorageEntity(_fakeStorageEntityDefinition))
           .Verifiable();
 
       persistenceModelLoaderMock.Setup(mock => mock.CreatePersistenceMappingValidator(rootClass1)).Returns(validatorMock1.Object).Verifiable();
@@ -488,7 +488,7 @@ public void PersistenceModelIsValidated_OverAllDerivedClasses ()
       persistenceModelLoaderMock
           .Setup(mock => mock.ApplyPersistenceModelToHierarchy(rootClass))
           .Callback(
-              (ClassDefinition classDefinition) =>
+              (TypeDefinition classDefinition) =>
               {
                 rootClass.SetStorageEntity(_fakeStorageEntityDefinition);
                 derivedClass1.SetStorageEntity(_fakeStorageEntityDefinition);
@@ -514,11 +514,11 @@ public void PersistenceModelIsValidated_OverAllDerivedClasses ()
     [Test]
     public void SetCurrentRejectsUnresolvedTypes ()
     {
-      _mockMappingLoader.Setup(_ => _.GetClassDefinitions()).Returns(_emptyClassDefinitions);
-      _mockMappingLoader.Setup(_ => _.GetRelationDefinitions(It.IsAny<IDictionary<Type, ClassDefinition>>())).Returns(_emptyRelationDefinitions);
+      _mockMappingLoader.Setup(_ => _.GetTypeDefinitions()).Returns(_emptyClassDefinitions);
+      _mockMappingLoader.Setup(_ => _.GetRelationDefinitions(It.IsAny<IDictionary<Type, TypeDefinition>>())).Returns(_emptyRelationDefinitions);
       _mockMappingLoader.Setup(_ => _.ResolveTypes).Returns(false);
       _mockMappingLoader.Setup(_ => _.NameResolver).Returns(_memberInformationNameResolver);
-      _mockMappingLoader.Setup(_ => _.CreateClassDefinitionValidator()).Returns(new ClassDefinitionValidator());
+      _mockMappingLoader.Setup(_ => _.CreateTypeDefinitionValidator()).Returns(new TypeDefinitionValidator());
       _mockMappingLoader.Setup(_ => _.CreatePropertyDefinitionValidator()).Returns(new PropertyDefinitionValidator());
       _mockMappingLoader.Setup(_ => _.CreateRelationDefinitionValidator()).Returns(new RelationDefinitionValidator());
       _mockMappingLoader.Setup(_ => _.CreateSortExpressionValidator()).Returns(new SortExpressionValidator());
@@ -534,33 +534,33 @@ public void SetCurrentRejectsUnresolvedTypes ()
                   "Argument 'mappingConfiguration' must have property 'ResolveTypes' set.", "mappingConfiguration"));
     }
 
-    private void StubMockMappingLoader (ClassDefinition[] classDefinitions, RelationDefinition[] relationDefinitions)
+    private void StubMockMappingLoader (TypeDefinition[] classDefinitions, RelationDefinition[] relationDefinitions)
     {
-      _mockMappingLoader.Setup(_ => _.GetClassDefinitions()).Returns(classDefinitions);
-      _mockMappingLoader.Setup(_ => _.GetRelationDefinitions(It.IsAny<IDictionary<Type, ClassDefinition>>())).Returns(relationDefinitions);
+      _mockMappingLoader.Setup(_ => _.GetTypeDefinitions()).Returns(classDefinitions);
+      _mockMappingLoader.Setup(_ => _.GetRelationDefinitions(It.IsAny<IDictionary<Type, TypeDefinition>>())).Returns(relationDefinitions);
       _mockMappingLoader.Setup(_ => _.ResolveTypes).Returns(true);
       _mockMappingLoader.Setup(_ => _.NameResolver).Returns(_memberInformationNameResolver);
-      _mockMappingLoader.Setup(_ => _.CreateClassDefinitionValidator()).Returns(new ClassDefinitionValidator());
+      _mockMappingLoader.Setup(_ => _.CreateTypeDefinitionValidator()).Returns(new TypeDefinitionValidator());
       _mockMappingLoader.Setup(_ => _.CreatePropertyDefinitionValidator()).Returns(new PropertyDefinitionValidator());
       _mockMappingLoader.Setup(_ => _.CreateRelationDefinitionValidator()).Returns(new RelationDefinitionValidator());
       _mockMappingLoader.Setup(_ => _.CreateSortExpressionValidator()).Returns(new SortExpressionValidator());
     }
 
-    private void StubMockMappingLoaderWithValidation (ClassDefinition[] classDefinitions, RelationDefinition[] relationDefinitions)
+    private void StubMockMappingLoaderWithValidation (TypeDefinition[] classDefinitions, RelationDefinition[] relationDefinitions)
     {
-      _mockMappingLoader.Setup(_ => _.GetClassDefinitions()).Returns(classDefinitions);
-      _mockMappingLoader.Setup(_ => _.GetRelationDefinitions(It.IsAny<IDictionary<Type, ClassDefinition>>())).Returns(relationDefinitions);
+      _mockMappingLoader.Setup(_ => _.GetTypeDefinitions()).Returns(classDefinitions);
+      _mockMappingLoader.Setup(_ => _.GetRelationDefinitions(It.IsAny<IDictionary<Type, TypeDefinition>>())).Returns(relationDefinitions);
       _mockMappingLoader.Setup(_ => _.ResolveTypes).Returns(true);
       _mockMappingLoader.Setup(_ => _.NameResolver).Returns(_memberInformationNameResolver);
-      _mockMappingLoader.Setup(_ => _.CreateClassDefinitionValidator()).Returns(CreateClassDefinitionValidator());
+      _mockMappingLoader.Setup(_ => _.CreateTypeDefinitionValidator()).Returns(CreateTypeDefinitionValidator());
       _mockMappingLoader.Setup(_ => _.CreatePropertyDefinitionValidator()).Returns(CreatePropertyDefinitionValidator());
       _mockMappingLoader.Setup(_ => _.CreateRelationDefinitionValidator()).Returns(CreateRelationDefinitionValidator());
       _mockMappingLoader.Setup(_ => _.CreateSortExpressionValidator()).Returns(CreateSortExpressionValidator());
     }
 
-    private ClassDefinitionValidator CreateClassDefinitionValidator ()
+    private TypeDefinitionValidator CreateTypeDefinitionValidator ()
     {
-      return new ClassDefinitionValidator(new DomainObjectTypeIsNotGenericValidationRule());
+      return new TypeDefinitionValidator(new DomainObjectTypeIsNotGenericValidationRule());
     }
 
     private PropertyDefinitionValidator CreatePropertyDefinitionValidator ()
@@ -583,7 +583,7 @@ private IPersistenceModelLoader CreatePersistenceModelLoaderStub ()
       var persistenceModelLoaderStub = new Mock<IPersistenceModelLoader>();
       persistenceModelLoaderStub
           .Setup(stub => stub.ApplyPersistenceModelToHierarchy(It.IsAny<ClassDefinition>()))
-          .Callback((ClassDefinition classDefinition) => classDefinition.SetStorageEntity(TableDefinitionObjectMother.Create(TestDomainStorageProviderDefinition)));
+          .Callback((TypeDefinition classDefinition) => classDefinition.SetStorageEntity(TableDefinitionObjectMother.Create(TestDomainStorageProviderDefinition)));
       persistenceModelLoaderStub
           .Setup(stub => stub.CreatePersistenceMappingValidator(It.IsAny<ClassDefinition>()))
           .Returns(new PersistenceMappingValidator());
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/IgnoredTypes/OnlyBaseClassNotInMapping/When_ASingleClassIsExcludedFromTheMapping.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/IgnoredTypes/OnlyBaseClassNotInMapping/When_ASingleClassIsExcludedFromTheMapping.cs
index 6b4d12ae5e..47de09c02f 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/IgnoredTypes/OnlyBaseClassNotInMapping/When_ASingleClassIsExcludedFromTheMapping.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/IgnoredTypes/OnlyBaseClassNotInMapping/When_ASingleClassIsExcludedFromTheMapping.cs
@@ -31,8 +31,8 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _baseClassOfExcludedClass = TypeDefinitions[typeof(BaseClassOfExcludedClass)];
-      _classDerivedFromExcludedClass = TypeDefinitions[typeof(ClassDerivedFromExcludedClass)];
+      _baseClassOfExcludedClass = GetClassDefinition(typeof(BaseClassOfExcludedClass));
+      _classDerivedFromExcludedClass = GetClassDefinition(typeof(ClassDerivedFromExcludedClass));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/MappingReflectionIntegrationTestBase.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/MappingReflectionIntegrationTestBase.cs
index e77056079c..4cbd4a3f4b 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/MappingReflectionIntegrationTestBase.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/MappingReflectionIntegrationTestBase.cs
@@ -35,7 +35,7 @@ public abstract class MappingReflectionIntegrationTestBase
     private static readonly IEnumerable<Type> s_domainObjectTypes =
         typeof(MappingReflectionTestBase).Assembly.GetTypes().Where(t => typeof(DomainObject).IsAssignableFrom(t)).ToArray();
 
-    private IDictionary<Type, ClassDefinition> _typeDefinitions;
+    private IDictionary<Type, TypeDefinition> _typeDefinitions;
 
     [SetUp]
     public virtual void SetUp ()
@@ -43,7 +43,7 @@ public virtual void SetUp ()
       var reflectedTypes = ForTheseReflectedTypes().ToArray();
       var mappingReflector = CreateMappingReflector(reflectedTypes);
 
-      var typeDefinitions = GetTypeDefinitionsAndValidateMapping(mappingReflector).ToDictionary(cd => cd.ClassType);
+      var typeDefinitions = GetTypeDefinitionsAndValidateMapping(mappingReflector).ToDictionary(cd => cd.Type);
       _typeDefinitions = typeDefinitions;
     }
 
@@ -54,20 +54,25 @@ public virtual void OneTimeSetUp ()
       StandardConfiguration.EnsureInitialized();
     }
 
-    protected IDictionary<Type, ClassDefinition> TypeDefinitions
+    protected IDictionary<Type, TypeDefinition> TypeDefinitions
     {
       get { return _typeDefinitions; }
     }
 
+    protected ClassDefinition GetClassDefinition (Type type)
+    {
+      return (ClassDefinition)TypeDefinitions[type];
+    }
+
     protected virtual IEnumerable<Type> ForTheseReflectedTypes ()
     {
       return AllDomainObjectTypesFromThisNamespace();
     }
 
     protected IRelationEndPointDefinition GetRelationEndPointDefinition (
-        ClassDefinition classDefinition, Type declaringType, string shortPropertyName)
+        TypeDefinition typeDefinition, Type declaringType, string shortPropertyName)
     {
-      return classDefinition.GetRelationEndPointDefinition(declaringType.FullName + "." + shortPropertyName);
+      return typeDefinition.GetRelationEndPointDefinition(declaringType.FullName + "." + shortPropertyName);
     }
 
     private IEnumerable<Type> AllDomainObjectTypesFromThisNamespace ()
@@ -85,7 +90,7 @@ private MappingReflector CreateMappingReflector (Type[] reflectedTypes)
       return MappingReflectorObjectMother.CreateMappingReflector(typeDiscoveryServiceStub.Object);
     }
 
-    private IEnumerable<ClassDefinition> GetTypeDefinitionsAndValidateMapping (MappingReflector mappingReflector)
+    private IEnumerable<TypeDefinition> GetTypeDefinitionsAndValidateMapping (MappingReflector mappingReflector)
     {
       var storageSettings = StandardConfiguration.Instance.GetStorageSettings();
       var persistenceModelLoader = new PersistenceModelLoader(storageSettings);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/Mixins/IntroducedRelations/When_ADerivedClass_ReceivesARelationViaMixin.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/Mixins/IntroducedRelations/When_ADerivedClass_ReceivesARelationViaMixin.cs
index 4211bd1579..9d154b3651 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/Mixins/IntroducedRelations/When_ADerivedClass_ReceivesARelationViaMixin.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/Mixins/IntroducedRelations/When_ADerivedClass_ReceivesARelationViaMixin.cs
@@ -34,8 +34,8 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _derivedClass = TypeDefinitions[typeof(Derived)];
-      _relationTarget = TypeDefinitions[typeof(RelationTarget)];
+      _derivedClass = GetClassDefinition(typeof(Derived));
+      _relationTarget = GetClassDefinition(typeof(RelationTarget));
 
       _relationEndPointPropertyInMixin = GetPropertyInformation((MixinAddingRelation m) => m.RelationTarget);
       _relationEndPointPropertyInRelationTarget = GetPropertyInformation((RelationTarget t) => t.Derived);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/ReferenceMappingComparisonTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/ReferenceMappingComparisonTest.cs
index 599fd896c3..1d3bb38cf7 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/ReferenceMappingComparisonTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/ReferenceMappingComparisonTest.cs
@@ -30,49 +30,49 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.MappingReflectionIntegra
   public class ReferenceMappingComparisonTest
   {
     [Test]
-    public void GetClassDefinitions ()
+    public void GetTypeDefinitions ()
     {
       MappingReflector mappingReflector = MappingReflectorObjectMother.CreateMappingReflector(TestMappingConfiguration.GetTypeDiscoveryService());
 
-      var actualClassDefinitions = mappingReflector.GetClassDefinitions().ToDictionary(cd => cd.ClassType);
-      mappingReflector.GetRelationDefinitions(actualClassDefinitions);
-      Assert.That(actualClassDefinitions, Is.Not.Null);
+      var actualTypeDefinitions = mappingReflector.GetTypeDefinitions().ToDictionary(td => td.Type);
+      mappingReflector.GetRelationDefinitions(actualTypeDefinitions);
+      Assert.That(actualTypeDefinitions, Is.Not.Null);
 
-      var inheritanceRootClasses = actualClassDefinitions.Values.Select(cd => cd.GetInheritanceRootClass()).Distinct();
+      var inheritanceRoots = TypeDefinitionHierarchy.GetHierarchyRoots(actualTypeDefinitions.Values);
 
       // Pretend that all classes have the storage provider definition used by FakeMappingConfiguration
       var defaultStorageProviderDefinition = FakeMappingConfiguration.Current.DefaultStorageProviderDefinition;
       var defaultStorageSettingsStub = new Mock<IStorageSettings>();
       defaultStorageSettingsStub
-          .Setup(stub => stub.GetStorageProviderDefinition(It.IsAny<ClassDefinition>()))
+          .Setup(stub => stub.GetStorageProviderDefinition(It.IsAny<TypeDefinition>()))
           .Returns(defaultStorageProviderDefinition);
 
       var nonPersistentStorageProviderDefinition = FakeMappingConfiguration.Current.NonPersistentStorageProviderDefinition;
       var storageSettingsStub = new Mock<IStorageSettings>();
       storageSettingsStub
-          .Setup(stub => stub.GetStorageProviderDefinition(It.IsAny<ClassDefinition>()))
+          .Setup(stub => stub.GetStorageProviderDefinition(It.IsAny<TypeDefinition>()))
           .Returns(nonPersistentStorageProviderDefinition);
 
-      foreach (ClassDefinition classDefinition in inheritanceRootClasses)
+      foreach (var inheritanceRoot in inheritanceRoots)
       {
-        if (typeof(OrderViewModel).IsAssignableFrom(classDefinition.ClassType))
+        if (typeof(OrderViewModel).IsAssignableFrom(inheritanceRoot.Type))
         {
           var persistenceModelLoader = nonPersistentStorageProviderDefinition.Factory.CreatePersistenceModelLoader(
               nonPersistentStorageProviderDefinition);
-          persistenceModelLoader.ApplyPersistenceModelToHierarchy(classDefinition);
+          persistenceModelLoader.ApplyPersistenceModelToHierarchy(inheritanceRoot);
         }
         else
         {
           var persistenceModelLoader = defaultStorageProviderDefinition.Factory.CreatePersistenceModelLoader(
               defaultStorageProviderDefinition);
-          persistenceModelLoader.ApplyPersistenceModelToHierarchy(classDefinition);
+          persistenceModelLoader.ApplyPersistenceModelToHierarchy(inheritanceRoot);
         }
       }
 
-      var classDefinitionChecker = new ClassDefinitionChecker();
-      classDefinitionChecker.Check(FakeMappingConfiguration.Current.TypeDefinitions.Values, actualClassDefinitions, false, true);
-      classDefinitionChecker.CheckPersistenceModel(FakeMappingConfiguration.Current.TypeDefinitions.Values, actualClassDefinitions);
-      Assert.That(actualClassDefinitions.ContainsKey(typeof(TestDomainBase)), Is.False);
+      var typeDefinitionChecker = new TypeDefinitionChecker();
+      typeDefinitionChecker.Check(FakeMappingConfiguration.Current.TypeDefinitions.Values.Cast<ClassDefinition>(), actualTypeDefinitions, false, true);
+      typeDefinitionChecker.CheckPersistenceModel(FakeMappingConfiguration.Current.TypeDefinitions.Values.Cast<ClassDefinition>(), actualTypeDefinitions);
+      Assert.That(actualTypeDefinitions.ContainsKey(typeof(TestDomainBase)), Is.False);
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/BidirectionalRelation/When_ABidirectionalRelationIsDeclaredAboveTheInheritanceRoot.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/BidirectionalRelation/When_ABidirectionalRelationIsDeclaredAboveTheInheritanceRoot.cs
index a0c5bf7eb5..0f529aff22 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/BidirectionalRelation/When_ABidirectionalRelationIsDeclaredAboveTheInheritanceRoot.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/BidirectionalRelation/When_ABidirectionalRelationIsDeclaredAboveTheInheritanceRoot.cs
@@ -34,8 +34,8 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _inheritanceRootClass = TypeDefinitions[typeof(InheritanceRoot)];
-      _relationTarget = TypeDefinitions[typeof(RelationTarget)];
+      _inheritanceRootClass = GetClassDefinition(typeof(InheritanceRoot));
+      _relationTarget = GetClassDefinition(typeof(RelationTarget));
 
       _propertyOnClassAboveInheritanceRoot = GetPropertyInformation((ClassAboveInheritanceRoot c) => c.RelationPropertyOnClassAboveInheritanceRoot);
       _propertyOnRelationTarget = GetPropertyInformation((RelationTarget t) => t.RelationProperty);
@@ -44,8 +44,8 @@ public override void SetUp ()
     [Test]
     public void GivenThat_TheRelationTarget_PointsBackToTheInheritanceRoot_WhichIsNotTheTypeDeclaringTheOppositeProperty ()
     {
-      Assert.That(_propertyOnRelationTarget.PropertyType, Is.SameAs(_inheritanceRootClass.ClassType));
-      Assert.That(_propertyOnClassAboveInheritanceRoot.DeclaringType, Is.Not.SameAs(_inheritanceRootClass.ClassType));
+      Assert.That(_propertyOnRelationTarget.PropertyType, Is.SameAs(_inheritanceRootClass.Type));
+      Assert.That(_propertyOnClassAboveInheritanceRoot.DeclaringType, Is.Not.SameAs(_inheritanceRootClass.Type));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/BidirectionalRelationInGenericBaseClass/When_GenericBidirectionalRelationDeclaredAboveInheritanceRoot.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/BidirectionalRelationInGenericBaseClass/When_GenericBidirectionalRelationDeclaredAboveInheritanceRoot.cs
index 3316d1436b..9bbc38486b 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/BidirectionalRelationInGenericBaseClass/When_GenericBidirectionalRelationDeclaredAboveInheritanceRoot.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/BidirectionalRelationInGenericBaseClass/When_GenericBidirectionalRelationDeclaredAboveInheritanceRoot.cs
@@ -35,8 +35,8 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _inheritanceRootClass = TypeDefinitions[typeof(InheritanceRoot)];
-      _relationTarget = TypeDefinitions[typeof(RelationTarget)];
+      _inheritanceRootClass = GetClassDefinition(typeof(InheritanceRoot));
+      _relationTarget = GetClassDefinition(typeof(RelationTarget));
 
       _propertyOnClassAboveInheritanceRoot = GetPropertyInformation(
           (GenericClassAboveInheritanceRoot<RelationTarget> c) => c.RelationPropertyOnClassAboveInheritanceRoot);
@@ -46,8 +46,8 @@ public override void SetUp ()
     [Test]
     public void GivenThat_TheRelationTarget_PointsBackToTheInheritanceRoot_WhichIsNotTheTypeDeclaringTheOppositeProperty ()
     {
-      Assert.That(_propertyOnRelationTarget.PropertyType, Is.SameAs(_inheritanceRootClass.ClassType));
-      Assert.That(_propertyOnClassAboveInheritanceRoot.DeclaringType, Is.Not.SameAs(_inheritanceRootClass.ClassType));
+      Assert.That(_propertyOnRelationTarget.PropertyType, Is.SameAs(_inheritanceRootClass.Type));
+      Assert.That(_propertyOnClassAboveInheritanceRoot.DeclaringType, Is.Not.SameAs(_inheritanceRootClass.Type));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/TwoClassesInheritingTheSameRelation/When_TwoClasses_InheritARelation_FromAboveInheritanceRoot.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/TwoClassesInheritingTheSameRelation/When_TwoClasses_InheritARelation_FromAboveInheritanceRoot.cs
index 88cb27b5e0..bdc2348277 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/TwoClassesInheritingTheSameRelation/When_TwoClasses_InheritARelation_FromAboveInheritanceRoot.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/RelationsAboveInheritanceRoot/TwoClassesInheritingTheSameRelation/When_TwoClasses_InheritARelation_FromAboveInheritanceRoot.cs
@@ -30,8 +30,8 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _derivedClass1 = TypeDefinitions[typeof(DerivedInheritanceRootClass1)];
-      _derivedClass2 = TypeDefinitions[typeof(DerivedInheritanceRootClass2)];
+      _derivedClass1 = GetClassDefinition(typeof(DerivedInheritanceRootClass1));
+      _derivedClass2 = GetClassDefinition(typeof(DerivedInheritanceRootClass2));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/ShadowedProperties/When_ADerivedClass_RedefinesAProperty.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/ShadowedProperties/When_ADerivedClass_RedefinesAProperty.cs
index 413a35807f..54a946cf7c 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/ShadowedProperties/When_ADerivedClass_RedefinesAProperty.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectionIntegrationTests/ShadowedProperties/When_ADerivedClass_RedefinesAProperty.cs
@@ -33,7 +33,7 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _derivedClassDefinition = TypeDefinitions[typeof(Shadower)];
+      _derivedClassDefinition = GetClassDefinition(typeof(Shadower));
       _baseClassDefinition = _derivedClassDefinition.BaseClass;
 
       _basePropertyInfo = GetPropertyInformation((Base b) => b.Name);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectorTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectorTest.cs
index 2216ae8643..ddd022c72d 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectorTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/MappingReflectorTest.cs
@@ -21,6 +21,7 @@
 using Remotion.Data.DomainObjects.ConfigurationLoader.ReflectionBasedConfigurationLoader;
 using Remotion.Data.DomainObjects.Infrastructure;
 using Remotion.Data.DomainObjects.Infrastructure.TypePipe;
+using Remotion.Data.DomainObjects.Mapping;
 using Remotion.Data.DomainObjects.Mapping.Validation;
 using Remotion.Data.DomainObjects.Mapping.Validation.Logical;
 using Remotion.Data.DomainObjects.Mapping.Validation.Reflection;
@@ -83,7 +84,7 @@ public void GetResolveTypes ()
     [Test]
     public void GetRelationDefinitions ()
     {
-      var actualClassDefinitions = _mappingReflector.GetClassDefinitions().ToDictionary(cd => cd.ClassType);
+      var actualClassDefinitions = _mappingReflector.GetTypeDefinitions().ToDictionary(td => td.Type);
       var actualRelationDefinitions = _mappingReflector.GetRelationDefinitions(actualClassDefinitions).ToDictionary(rd => rd.ID);
 
       var relationDefinitionChecker = new RelationDefinitionChecker();
@@ -95,14 +96,14 @@ public void Get_WithDuplicateAssembly ()
     {
       var assembly = GetType().Assembly;
       var expectedMappingReflector = MappingReflectorObjectMother.CreateMappingReflector(BaseConfiguration.GetTypeDiscoveryService(assembly));
-      var expectedClassDefinitions = expectedMappingReflector.GetClassDefinitions().ToDictionary(cd=>cd.ClassType);
+      var expectedClassDefinitions = expectedMappingReflector.GetTypeDefinitions().ToDictionary(td => td.Type);
       var expectedRelationDefinitions = expectedMappingReflector.GetRelationDefinitions(expectedClassDefinitions);
 
       var mappingReflector = MappingReflectorObjectMother.CreateMappingReflector(BaseConfiguration.GetTypeDiscoveryService(assembly, assembly));
-      var actualClassDefinitions = mappingReflector.GetClassDefinitions().ToDictionary(cd => cd.ClassType);
+      var actualClassDefinitions = mappingReflector.GetTypeDefinitions().ToDictionary(td => td.Type);
 
-      var classDefinitionChecker = new ClassDefinitionChecker();
-      classDefinitionChecker.Check(expectedClassDefinitions.Values, actualClassDefinitions, false, false);
+      var typeDefinitionChecker = new TypeDefinitionChecker();
+      typeDefinitionChecker.Check(expectedClassDefinitions.Values, actualClassDefinitions, false, false);
 
       var actualRelationDefinitions = mappingReflector.GetRelationDefinitions(actualClassDefinitions).ToDictionary(rd => rd.ID);
       var relationDefinitionChecker = new RelationDefinitionChecker();
@@ -114,7 +115,7 @@ public void GetClassDefinitions ()
     {
       var assembly = GetType().Assembly;
       var mappingReflector = MappingReflectorObjectMother.CreateMappingReflector(BaseConfiguration.GetTypeDiscoveryService(assembly, assembly));
-      var classDefinitions = mappingReflector.GetClassDefinitions();
+      var classDefinitions = mappingReflector.GetTypeDefinitions();
 
       Assert.That(classDefinitions, Is.Not.Empty);
     }
@@ -122,7 +123,7 @@ public void GetClassDefinitions ()
     [Test]
     public void CreateClassDefinitionValidator ()
     {
-      var validator = (ClassDefinitionValidator)_mappingReflector.CreateClassDefinitionValidator();
+      var validator = (TypeDefinitionValidator)_mappingReflector.CreateTypeDefinitionValidator();
 
       Assert.That(validator.ValidationRules.Count, Is.EqualTo(7));
       Assert.That(validator.ValidationRules[0], Is.TypeOf(typeof(DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRule)));
@@ -163,7 +164,7 @@ public void CreateRelationDefinitionValidator ()
       Assert.That(validator.ValidationRules[6], Is.TypeOf(typeof(RelationEndPointNamesAreConsistentValidationRule)));
       Assert.That(validator.ValidationRules[7], Is.TypeOf(typeof(RelationEndPointTypesAreConsistentValidationRule)));
       Assert.That(validator.ValidationRules[8], Is.TypeOf(typeof(CheckForInvalidRelationEndPointsValidationRule)));
-      Assert.That(validator.ValidationRules[9], Is.TypeOf(typeof(CheckForTypeNotFoundClassDefinitionValidationRule)));
+      Assert.That(validator.ValidationRules[9], Is.TypeOf(typeof(CheckForTypeNotFoundTypeDefinitionValidationRule)));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionCollectionFactoryTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionCollectionFactoryTest.cs
index c9a99f1560..ee401220d1 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionCollectionFactoryTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionCollectionFactoryTest.cs
@@ -39,24 +39,24 @@ public void SetUp ()
     [Test]
     public void CreatePropertyDefinitions ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order), baseClass: null);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order), baseClass: null);
 
       var propertyInfo1 = PropertyInfoAdapter.Create(typeof(Order).GetProperty("OrderNumber"));
       var propertyInfo2 = PropertyInfoAdapter.Create(typeof(Order).GetProperty("DeliveryDate"));
 
-      var fakePropertyDefinition1 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition, "P1");
-      var fakePropertyDefinition2 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition, "P2");
+      var fakePropertyDefinition1 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(typeDefinition, "P1");
+      var fakePropertyDefinition2 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(typeDefinition, "P2");
 
       _mappingObjectFactoryMock
-          .Setup(mock => mock.CreatePropertyDefinition(classDefinition, propertyInfo1))
+          .Setup(mock => mock.CreatePropertyDefinition(typeDefinition, propertyInfo1))
           .Returns(fakePropertyDefinition1)
           .Verifiable();
       _mappingObjectFactoryMock
-          .Setup(mock => mock.CreatePropertyDefinition(classDefinition, propertyInfo2))
+          .Setup(mock => mock.CreatePropertyDefinition(typeDefinition, propertyInfo2))
           .Returns(fakePropertyDefinition2)
           .Verifiable();
 
-      var result = _factory.CreatePropertyDefinitions(classDefinition, new[] { propertyInfo1, propertyInfo2 });
+      var result = _factory.CreatePropertyDefinitions(typeDefinition, new[] { propertyInfo1, propertyInfo2 });
 
       _mappingObjectFactoryMock.Verify();
       Assert.That(result.Count, Is.EqualTo(2));
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionCollectionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionCollectionTest.cs
index f851ec4559..2a1574697f 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionCollectionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionCollectionTest.cs
@@ -40,7 +40,7 @@ public override void SetUp ()
     [Test]
     public void CreateForAllPropertyDefinitions_ClassDefinitionWithoutBaseClassDefinition_MakeCollectionReadOnlyIsFalse ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
+      var classDefinition = TypeDefinitionObjectMother.CreateClassDefinition();
       var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition);
 
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
@@ -55,7 +55,7 @@ public void CreateForAllPropertyDefinitions_ClassDefinitionWithoutBaseClassDefin
     [Test]
     public void CreateForAllPropertyDefinitions_ClassDefinitionWithoutBaseClassDefinition_MakeCollectionReadOnlyIsTrue ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
+      var classDefinition = TypeDefinitionObjectMother.CreateClassDefinition();
       var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition);
 
       classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, false));
@@ -71,21 +71,44 @@ public void CreateForAllPropertyDefinitions_ClassDefinitionWithoutBaseClassDefin
     public void CreateForAllPropertyDefinitions_ClassDefinitionWithBaseClassDefinition ()
     {
       var baseClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Company));
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Partner), baseClass: baseClassDefinition);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Partner), baseClass: baseClassDefinition);
 
       var propertyDefinitionInBaseClass = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(baseClassDefinition, "Property1");
-      var propertyDefinitionInDerivedClass = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition, "Property2");
+      var propertyDefinitionInDerivedClass = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(typeDefinition, "Property2");
 
       baseClassDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinitionInBaseClass }, true));
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinitionInDerivedClass }, true));
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinitionInDerivedClass }, true));
 
-      var propertyDefinitions = PropertyDefinitionCollection.CreateForAllProperties(classDefinition, false);
+      var propertyDefinitions = PropertyDefinitionCollection.CreateForAllProperties(typeDefinition, false);
 
       Assert.That(propertyDefinitions.Count, Is.EqualTo(2));
       Assert.That(propertyDefinitions[0], Is.SameAs(propertyDefinitionInDerivedClass));
       Assert.That(propertyDefinitions[1], Is.SameAs(propertyDefinitionInBaseClass));
     }
 
+    [Test]
+    public void CreateForAllPropertyDefinitions_ClassDefinitionWithImplementedInterfaces ()
+    {
+      var iPerson = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      var iCustomer = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(extendedInterfaces: new[] { iPerson });
+      var customer = ClassDefinitionObjectMother.CreateClassDefinition(implementedInterfaces: new[] { iCustomer });
+
+      var propertyDefinitionInIPerson = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(iPerson, "A");
+      var propertyDefinitionInICustomer = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(iCustomer, "B");
+      var propertyDefinitionInCustomer = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(customer, "C");
+
+      iPerson.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinitionInIPerson }, true));
+      iCustomer.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinitionInICustomer }, true));
+      customer.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinitionInCustomer }, true));
+
+      var propertyDefinitions = PropertyDefinitionCollection.CreateForAllProperties(customer, false);
+
+      Assert.That(propertyDefinitions.Count, Is.EqualTo(3));
+      Assert.That(propertyDefinitions[0], Is.SameAs(propertyDefinitionInCustomer));
+      Assert.That(propertyDefinitions[1], Is.SameAs(propertyDefinitionInICustomer));
+      Assert.That(propertyDefinitions[2], Is.SameAs(propertyDefinitionInIPerson));
+    }
+
     [Test]
     public void Add ()
     {
@@ -134,7 +157,7 @@ public void ContainsPropertyDefinitionFalse ()
 
       var copy =
           new PropertyDefinition(
-              _propertyDefinition.ClassDefinition,
+              _propertyDefinition.TypeDefinition,
               _propertyDefinition.PropertyInfo,
               _propertyDefinition.PropertyName,
               _propertyDefinition.IsObjectID,
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionObjectMother.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionObjectMother.cs
index c14b8054be..833cd8dc4d 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionObjectMother.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionObjectMother.cs
@@ -31,12 +31,12 @@ public static class PropertyDefinitionObjectMother
   {
     public static PropertyDefinition CreateForFakePropertyInfo ()
     {
-      return CreateForFakePropertyInfo(ClassDefinitionObjectMother.CreateClassDefinition());
+      return CreateForFakePropertyInfo(TypeDefinitionObjectMother.CreateClassDefinition());
     }
 
     public static PropertyDefinition CreateForFakePropertyInfo (string propertyName, StorageClass storageClass)
     {
-      return CreateForFakePropertyInfo(ClassDefinitionObjectMother.CreateClassDefinition(), propertyName, storageClass);
+      return CreateForFakePropertyInfo(TypeDefinitionObjectMother.CreateClassDefinition(), propertyName, storageClass);
     }
 
     public static PropertyDefinition CreateForFakePropertyInfo (string propertyName, Type propertyType)
@@ -46,37 +46,37 @@ public static PropertyDefinition CreateForFakePropertyInfo (string propertyName,
 
     public static PropertyDefinition CreateForFakePropertyInfo (string propertyName, Type propertyType, bool isNullable)
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
-      return CreateForFakePropertyInfo(classDefinition, propertyName, false, propertyType, isNullable, null, StorageClass.Persistent);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition();
+      return CreateForFakePropertyInfo(typeDefinition, propertyName, false, propertyType, isNullable, null, StorageClass.Persistent);
     }
 
-    public static PropertyDefinition CreateForFakePropertyInfo (ClassDefinition classDefinition)
+    public static PropertyDefinition CreateForFakePropertyInfo (TypeDefinition typeDefinition)
     {
-      return CreateForFakePropertyInfo(classDefinition, "Test");
+      return CreateForFakePropertyInfo(typeDefinition, "Test");
     }
 
-    public static PropertyDefinition CreateForFakePropertyInfo (ClassDefinition classDefinition, string propertyName)
+    public static PropertyDefinition CreateForFakePropertyInfo (TypeDefinition typeDefinition, string propertyName)
     {
-      return CreateForFakePropertyInfo(classDefinition, propertyName, false, typeof(string), true, null, StorageClass.Persistent);
+      return CreateForFakePropertyInfo(typeDefinition, propertyName, false, typeof(string), true, null, StorageClass.Persistent);
     }
 
-    public static PropertyDefinition CreateForFakePropertyInfo (ClassDefinition classDefinition, string propertyName, StorageClass storageClass)
+    public static PropertyDefinition CreateForFakePropertyInfo (TypeDefinition typeDefinition, string propertyName, StorageClass storageClass)
     {
-      return CreateForFakePropertyInfo(classDefinition, propertyName, false, typeof(string), true, null, storageClass);
+      return CreateForFakePropertyInfo(typeDefinition, propertyName, false, typeof(string), true, null, storageClass);
     }
 
-    public static PropertyDefinition CreateForFakePropertyInfo (ClassDefinition classDefinition, string propertyName, Type propertyType)
+    public static PropertyDefinition CreateForFakePropertyInfo (TypeDefinition typeDefinition, string propertyName, Type propertyType)
     {
-      return CreateForFakePropertyInfo(classDefinition, propertyName, false, propertyType, true, null, StorageClass.Persistent);
+      return CreateForFakePropertyInfo(typeDefinition, propertyName, false, propertyType, true, null, StorageClass.Persistent);
     }
 
-    public static PropertyDefinition CreateForFakePropertyInfo (ClassDefinition classDefinition, bool isNullable)
+    public static PropertyDefinition CreateForFakePropertyInfo (TypeDefinition typeDefinition, bool isNullable)
     {
-      return CreateForFakePropertyInfo(classDefinition, "Test", false, typeof(string), isNullable, null, StorageClass.Persistent);
+      return CreateForFakePropertyInfo(typeDefinition, "Test", false, typeof(string), isNullable, null, StorageClass.Persistent);
     }
 
     public static PropertyDefinition CreateForFakePropertyInfo (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         bool isObjectID,
         Type propertyType,
@@ -84,7 +84,7 @@ public static PropertyDefinition CreateForFakePropertyInfo (
         int? maxLength,
         StorageClass storageClass)
     {
-      var declaringType = classDefinition.ClassType;
+      var declaringType = typeDefinition.Type;
 
       var propertyInformationStub = new Mock<IPropertyInformation>();
       propertyInformationStub.Setup(stub => stub.Name).Returns(propertyName + "FakeProperty");
@@ -95,43 +95,43 @@ public static PropertyDefinition CreateForFakePropertyInfo (
       var defaultValue = isNullable ? null : propertyType.GetDefaultValue();
 
       IPropertyInformation propertyInformation = propertyInformationStub.Object;
-      return CreateForPropertyInformation(classDefinition, propertyName, isObjectID, isNullable, maxLength, storageClass, propertyInformation, defaultValue);
+      return CreateForPropertyInformation(typeDefinition, propertyName, isObjectID, isNullable, maxLength, storageClass, propertyInformation, defaultValue);
     }
 
     public static PropertyDefinition CreateForFakePropertyInfo_ObjectID ()
     {
-      return CreateForFakePropertyInfo_ObjectID(ClassDefinitionObjectMother.CreateClassDefinition());
+      return CreateForFakePropertyInfo_ObjectID(TypeDefinitionObjectMother.CreateClassDefinition());
     }
 
-    public static PropertyDefinition CreateForFakePropertyInfo_ObjectID (ClassDefinition classDefinition)
+    public static PropertyDefinition CreateForFakePropertyInfo_ObjectID (TypeDefinition typeDefinition)
     {
-      return CreateForFakePropertyInfo_ObjectID(classDefinition, "Test");
+      return CreateForFakePropertyInfo_ObjectID(typeDefinition, "Test");
     }
 
-    public static PropertyDefinition CreateForFakePropertyInfo_ObjectID (ClassDefinition classDefinition, string propertyName)
+    public static PropertyDefinition CreateForFakePropertyInfo_ObjectID (TypeDefinition typeDefinition, string propertyName)
     {
-      return CreateForFakePropertyInfo(classDefinition, propertyName, true, typeof(ObjectID), true, null, StorageClass.Persistent);
+      return CreateForFakePropertyInfo(typeDefinition, propertyName, true, typeof(ObjectID), true, null, StorageClass.Persistent);
     }
 
-    public static PropertyDefinition CreateForFakePropertyInfo_ObjectID (ClassDefinition classDefinition, string propertyName, StorageClass storageClass)
+    public static PropertyDefinition CreateForFakePropertyInfo_ObjectID (TypeDefinition typeDefinition, string propertyName, StorageClass storageClass)
     {
-      return CreateForFakePropertyInfo(classDefinition, propertyName, true, typeof(ObjectID), true, null, storageClass);
+      return CreateForFakePropertyInfo(typeDefinition, propertyName, true, typeof(ObjectID), true, null, storageClass);
     }
 
-    public static PropertyDefinition CreateForRealPropertyInfo (ClassDefinition classDefinition, Type declaringClassType, string propertyName)
+    public static PropertyDefinition CreateForRealPropertyInfo (TypeDefinition typeDefinition, Type declaringType, string propertyName)
     {
-      var propertyInfo = declaringClassType.GetProperty(
+      var propertyInfo = declaringType.GetProperty(
           propertyName,
           BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.DeclaredOnly | BindingFlags.Instance);
-      Assert.IsNotNull(propertyInfo, "Property '" + propertyName + "' on type '" + declaringClassType + "'.");
+      Assert.IsNotNull(propertyInfo, "Property '" + propertyName + "' on type '" + declaringType + "'.");
 
-      var fullPropertyName = declaringClassType.FullName + "." + propertyName;
+      var fullPropertyName = declaringType.FullName + "." + propertyName;
 
       var isObjectID = ReflectionUtility.IsDomainObject(propertyInfo.PropertyType);
 
       IPropertyInformation propertyInformation = PropertyInfoAdapter.Create(propertyInfo);
       return CreateForPropertyInformation(
-          classDefinition,
+          typeDefinition,
           fullPropertyName,
           isObjectID,
           true,
@@ -142,12 +142,12 @@ public static PropertyDefinition CreateForRealPropertyInfo (ClassDefinition clas
     }
 
     public static PropertyDefinition CreateForPropertyInformation (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         IPropertyInformation propertyInformation)
     {
       return CreateForPropertyInformation(
-          classDefinition,
+          typeDefinition,
           propertyName,
           false,
           false,
@@ -158,12 +158,12 @@ public static PropertyDefinition CreateForPropertyInformation (
     }
 
     public static PropertyDefinition CreateForPropertyInformation (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         StorageClass storageClass,
         IPropertyInformation propertyInformation)
     {
       return CreateForPropertyInformation(
-          classDefinition,
+          typeDefinition,
           "Test",
           false,
           false,
@@ -174,7 +174,7 @@ public static PropertyDefinition CreateForPropertyInformation (
     }
 
     private static PropertyDefinition CreateForPropertyInformation (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         bool isObjectID,
         bool isNullable,
@@ -184,7 +184,7 @@ private static PropertyDefinition CreateForPropertyInformation (
         object defaultValue)
     {
       var propertyDefinition = new PropertyDefinition(
-          classDefinition,
+          typeDefinition,
           propertyInformation,
           propertyName,
           isObjectID,
@@ -197,7 +197,7 @@ private static PropertyDefinition CreateForPropertyInformation (
 
     public static PropertyDefinition CreateForFakePropertyInfo_MaxLength (string propertyName, Type propertyType, int maxLength)
     {
-      return CreateForFakePropertyInfo(ClassDefinitionObjectMother.CreateClassDefinition(), propertyName, false, propertyType, true, maxLength, StorageClass.Persistent);
+      return CreateForFakePropertyInfo(TypeDefinitionObjectMother.CreateClassDefinition(), propertyName, false, propertyType, true, maxLength, StorageClass.Persistent);
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionTest.cs
index 36ff707bcc..1475e76c2c 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyDefinitionTest.cs
@@ -27,14 +27,14 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   [TestFixture]
   public class PropertyDefinitionTest : StandardMappingTest
   {
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
     private Mock<IPropertyInformation> _propertyInformationStub;
 
     public override void SetUp ()
     {
       base.SetUp();
 
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition();
       _propertyInformationStub = new Mock<IPropertyInformation>();
       _propertyInformationStub.Setup(stub => stub.Name).Returns("Test");
       _propertyInformationStub.Setup(stub => stub.DeclaringType).Returns(TypeAdapter.Create(typeof(Order)));
@@ -46,9 +46,9 @@ public void Initialize ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(string));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, null);
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, null);
 
-      Assert.That(actual.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(actual.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(actual.IsNullable, Is.False);
       Assert.That(actual.MaxLength, Is.Null);
       Assert.That(actual.PropertyName, Is.EqualTo("Test"));
@@ -63,7 +63,7 @@ public void Initialize_WithReferenceType_IsNullableFalse ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(string));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, null);
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, null);
 
       Assert.That(actual.IsNullable, Is.False);
     }
@@ -73,7 +73,7 @@ public void Initialize_WithReferenceType_IsNullableTrue ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(string));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, true, null, StorageClass.Persistent, null);
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, true, null, StorageClass.Persistent, null);
 
       Assert.That(actual.IsNullable, Is.True);
     }
@@ -83,7 +83,7 @@ public void Initialize_WithNonNullableValueType_IsNullableFalse ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(int));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, default(int));
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, default(int));
 
       Assert.That(actual.IsNullable, Is.False);
     }
@@ -93,7 +93,7 @@ public void Initialize_WithNullableValueType_IsNullableFalse ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(int?));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, null);
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, null);
 
       Assert.That(actual.IsNullable, Is.False);
     }
@@ -103,7 +103,7 @@ public void Initialize_WithNullableValueType_IsNullableTrue ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(int?));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, true, null, StorageClass.Persistent, null);
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, true, null, StorageClass.Persistent, null);
 
       Assert.That(actual.IsNullable, Is.True);
     }
@@ -113,7 +113,7 @@ public void Initialize_WithString_MaxLengthSet ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(string));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, true, 50, StorageClass.Persistent, null);
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, true, 50, StorageClass.Persistent, null);
 
       Assert.That(actual.MaxLength, Is.EqualTo(50));
     }
@@ -123,7 +123,7 @@ public void Initialize_WithString_MaxLengthNotSet ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(string));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, true, null, StorageClass.Persistent, null);
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, true, null, StorageClass.Persistent, null);
 
       Assert.That(actual.MaxLength, Is.Null);
     }
@@ -133,7 +133,7 @@ public void Initialize_WithByteArray_MaxLengthSet ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(byte[]));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, true, 50, StorageClass.Persistent, null);
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, true, 50, StorageClass.Persistent, null);
 
       Assert.That(actual.MaxLength, Is.EqualTo(50));
     }
@@ -143,7 +143,7 @@ public void Initialize_WithByteArrayString_MaxLengthNotSet ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(byte[]));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, true, null, StorageClass.Persistent, null);
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, true, null, StorageClass.Persistent, null);
 
       Assert.That(actual.MaxLength, Is.Null);
     }
@@ -153,7 +153,7 @@ public void Initialize_WithOtherType_MaxLengthNotSet ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(int));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, default(int));
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, default(int));
 
       Assert.That(actual.MaxLength, Is.Null);
     }
@@ -163,7 +163,7 @@ public void IsObjectID_True ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(DomainObject));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", true, false, null, StorageClass.Persistent, null);
+          _typeDefinition, _propertyInformationStub.Object, "Test", true, false, null, StorageClass.Persistent, null);
       Assert.That(actual.IsObjectID, Is.True);
     }
 
@@ -172,14 +172,14 @@ public void IsObjectID_False ()
     {
       _propertyInformationStub.Setup(stub => stub.PropertyType).Returns(typeof(int));
       var actual = new PropertyDefinition(
-          _classDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, default(int));
+          _typeDefinition, _propertyInformationStub.Object, "Test", false, false, null, StorageClass.Persistent, default(int));
       Assert.That(actual.IsObjectID, Is.False);
     }
 
     [Test]
     public new void ToString ()
     {
-      PropertyDefinition propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_classDefinition, "ThePropertyName");
+      PropertyDefinition propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_typeDefinition, "ThePropertyName");
 
       Assert.That(propertyDefinition.ToString(), Is.EqualTo(typeof(PropertyDefinition).FullName + ": ThePropertyName"));
     }
@@ -187,7 +187,7 @@ public void IsObjectID_False ()
     [Test]
     public void SetStorageProperty ()
     {
-      PropertyDefinition propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_classDefinition);
+      PropertyDefinition propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_typeDefinition);
       var storagePropertyDefinition = SimpleStoragePropertyDefinitionObjectMother.CreateStorageProperty("Test");
 
       propertyDefinition.SetStorageProperty(storagePropertyDefinition);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyReflectorTests/BaseTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyReflectorTests/BaseTest.cs
index 3ae9f11242..d5966f406a 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyReflectorTests/BaseTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/PropertyReflectorTests/BaseTest.cs
@@ -33,34 +33,34 @@ protected PropertyReflector CreatePropertyReflector<T> (
       ArgumentUtility.CheckNotNullOrEmpty("property", property);
 
       Type type = typeof(T);
-      ClassDefinition classDefinition;
+      TypeDefinition typeDefinition;
       if (ReflectionUtility.IsDomainObject(type))
       {
-        classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: type, isAbstract: true);
+        typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: type, isAbstract: true);
       }
       else
       {
-        classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: type, isAbstract: false);
+        typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: type, isAbstract: false);
       }
 
-      return CreatePropertyReflector<T>(property, classDefinition, domainModelConstraintProvider, propertyDefaultValueProvider);
+      return CreatePropertyReflector<T>(property, typeDefinition, domainModelConstraintProvider, propertyDefaultValueProvider);
     }
 
     protected PropertyReflector CreatePropertyReflector<T> (
         string property,
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         IDomainModelConstraintProvider domainModelConstraintProvider,
         IPropertyDefaultValueProvider propertyDefaultValueProvider)
     {
       ArgumentUtility.CheckNotNullOrEmpty("property", property);
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
       Type type = typeof(T);
       var propertyInfo = PropertyInfoAdapter.Create(
           type.GetProperty(property, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic));
 
       return new PropertyReflector(
-          classDefinition,
+          typeDefinition,
           propertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/ReflectionBasedMappingObjectFactoryTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/ReflectionBasedMappingObjectFactoryTest.cs
index 2ce3b6de47..51f895018f 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/ReflectionBasedMappingObjectFactoryTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/ReflectionBasedMappingObjectFactoryTest.cs
@@ -57,7 +57,7 @@ public void CreateClassDefinition ()
       var result = _factory.CreateClassDefinition(typeof(Order), null);
 
       Assert.That(result, Is.Not.Null);
-      Assert.That(result.ClassType, Is.SameAs(typeof(Order)));
+      Assert.That(result.Type, Is.SameAs(typeof(Order)));
       Assert.That(result.InstanceCreator, Is.SameAs(_domainObjectCreator));
       Assert.That(result.BaseClass, Is.Null);
     }
@@ -71,7 +71,7 @@ public void CreateClassDefinition_WithBaseClass ()
       var result = _factory.CreateClassDefinition(typeof(Customer), companyClass);
 
       Assert.That(result, Is.Not.Null);
-      Assert.That(result.ClassType, Is.SameAs(typeof(Customer)));
+      Assert.That(result.Type, Is.SameAs(typeof(Customer)));
       Assert.That(result.InstanceCreator, Is.SameAs(_domainObjectCreator));
       Assert.That(result.BaseClass, Is.SameAs(companyClass));
     }
@@ -96,7 +96,7 @@ public void CreateRelationDefinition ()
 
       var result =
           _factory.CreateRelationDefinition(
-              new[] { orderClassDefinition, orderItemClassDefinition }.ToDictionary(cd => cd.ClassType),
+              new TypeDefinition[] { orderClassDefinition, orderItemClassDefinition }.ToDictionary(cd => cd.Type),
               orderItemClassDefinition,
               orderItemClassDefinition.MyRelationEndPointDefinitions[0].PropertyInfo);
 
@@ -112,10 +112,10 @@ public void CreateRelationDefinition ()
     [Test]
     public void CreateRelationEndPointDefinition ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order), baseClass: null);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order), baseClass: null);
       var propertyInfo = PropertyInfoAdapter.Create(typeof(Order).GetProperty("OrderItems"));
 
-      var result = _factory.CreateRelationEndPointDefinition(classDefinition, propertyInfo);
+      var result = _factory.CreateRelationEndPointDefinition(typeDefinition, propertyInfo);
 
       Assert.That(result, Is.TypeOf(typeof(DomainObjectCollectionRelationEndPointDefinition)));
       Assert.That(((DomainObjectCollectionRelationEndPointDefinition)result).PropertyInfo, Is.SameAs(propertyInfo));
@@ -124,21 +124,21 @@ public void CreateRelationEndPointDefinition ()
     [Test]
     public void CreateClassDefinitionCollection ()
     {
-      var result = _factory.CreateClassDefinitionCollection(new[] { typeof(Order), typeof(Company) });
+      var result = _factory.CreateTypeDefinitionCollection(new[] { typeof(Order), typeof(Company) });
 
       Assert.That(result.Length, Is.EqualTo(2));
-      Assert.That(result.Any(cd => cd.ClassType == typeof(Order)));
-      Assert.That(result.Any(cd => cd.ClassType == typeof(Company)));
+      Assert.That(result.Any(cd => cd.Type == typeof(Order)));
+      Assert.That(result.Any(cd => cd.Type == typeof(Company)));
     }
 
     [Test]
     public void CreatePropertyDefinitionCollection ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order), baseClass: null);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order), baseClass: null);
       var propertyInfo1 = PropertyInfoAdapter.Create(typeof(Order).GetProperty("OrderNumber"));
       var propertyInfo2 = PropertyInfoAdapter.Create(typeof(Order).GetProperty("DeliveryDate"));
 
-      var result = _factory.CreatePropertyDefinitionCollection(classDefinition, new[] { propertyInfo1, propertyInfo2 });
+      var result = _factory.CreatePropertyDefinitionCollection(typeDefinition, new[] { propertyInfo1, propertyInfo2 });
 
       Assert.That(result.Count, Is.EqualTo(2));
       Assert.That(result[0].PropertyInfo, Is.SameAs(propertyInfo1));
@@ -148,13 +148,13 @@ public void CreatePropertyDefinitionCollection ()
     [Test]
     public void CreateRelationDefinitionCollection ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(OrderItem));
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(classDefinition, typeof(OrderItem), "Order");
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixinsAndDefaultProperties(typeof(OrderItem));
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(typeDefinition, typeof(OrderItem), "Order");
       var endPoint = new RelationEndPointDefinition(propertyDefinition, false);
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      classDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPoint }, true));
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      typeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPoint }, true));
 
-      var result = _factory.CreateRelationDefinitionCollection(new[] { classDefinition }.ToDictionary(cd => cd.ClassType));
+      var result = _factory.CreateRelationDefinitionCollection(new TypeDefinition[] { typeDefinition }.ToDictionary(cd => cd.Type));
 
       Assert.That(result.Count(), Is.EqualTo(1));
       Assert.That(
@@ -168,11 +168,11 @@ public void CreateRelationDefinitionCollection ()
     [Test]
     public void CreateRelationEndPointDefinitionCollection ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(OrderTicket), baseClass: null);
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(classDefinition, typeof(OrderTicket), "Order");
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(OrderTicket), baseClass: null);
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(typeDefinition, typeof(OrderTicket), "Order");
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
 
-      var result = _factory.CreateRelationEndPointDefinitionCollection(classDefinition);
+      var result = _factory.CreateRelationEndPointDefinitionCollection(typeDefinition);
 
       Assert.That(result.Count, Is.EqualTo(1));
       Assert.That(
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionChecker.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionChecker.cs
index 46eb9af66e..db3858e231 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionChecker.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionChecker.cs
@@ -69,18 +69,19 @@ public void Check (RelationDefinition expectedDefinition, RelationDefinition act
       CheckEndPointDefinitions(expectedDefinition, actualDefinition);
     }
 
-    private void CheckEndPointDefinitions (RelationDefinition expectedRelationDefinition, RelationDefinition actualRelationDefinition)
+    private void CheckEndPointDefinitions (RelationDefinition expectedRelationDefinition, RelationDefinition actualRelationDefinition) // TODO R2I this needs to be rewritten for TypeDefinition
     {
       foreach (IRelationEndPointDefinition expectedEndPointDefinition in expectedRelationDefinition.EndPointDefinitions)
       {
         IRelationEndPointDefinition actualEndPointDefinition = actualRelationDefinition.GetEndPointDefinition(
-          expectedEndPointDefinition.ClassDefinition.ID, expectedEndPointDefinition.PropertyName);
+            expectedEndPointDefinition.TypeDefinition.Type,
+            expectedEndPointDefinition.PropertyName);
 
         Assert.IsNotNull(
             actualEndPointDefinition,
-            "End point definition was not found (relation definition: '{0}', class: '{1}', property name: '{2}').",
+            "End point definition was not found (relation definition: '{0}', type: '{1}', property name: '{2}').",
             expectedRelationDefinition.ID,
-            expectedEndPointDefinition.ClassDefinition.ID,
+            expectedEndPointDefinition.TypeDefinition.Type,
             expectedEndPointDefinition.PropertyName);
 
         var endPointDefinitionChecker = new RelationEndPointDefinitionChecker();
@@ -89,9 +90,9 @@ private void CheckEndPointDefinitions (RelationDefinition expectedRelationDefini
         Assert.AreSame(
             actualRelationDefinition,
             actualEndPointDefinition.RelationDefinition,
-            "End point definition does not reference the correct relation definition (relation definition: '{0}', class: '{1}', property name: '{2}').",
+            "End point definition does not reference the correct relation definition (relation definition: '{0}', type: '{1}', property name: '{2}').",
             actualRelationDefinition.ID,
-            actualEndPointDefinition.ClassDefinition.ID,
+            actualEndPointDefinition.TypeDefinition.Type,
             actualEndPointDefinition.PropertyName);
       }
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionCollectionFactoryTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionCollectionFactoryTest.cs
index 2cd6a65a2a..9574dad707 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionCollectionFactoryTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionCollectionFactoryTest.cs
@@ -27,8 +27,8 @@ public class RelationDefinitionCollectionFactoryTest : StandardMappingTest
   {
     private RelationDefinitionCollectionFactory _factory;
     private Mock<IMappingObjectFactory> _mappingObjectFactoryMock;
-    private ClassDefinition _orderClassDefinition;
-    private ClassDefinition _orderItemClassDefinition;
+    private TypeDefinition _orderTypeDefinition;
+    private TypeDefinition _orderItemTypeDefinition;
     private RelationDefinition _fakeRelationDefinition1;
     private RelationDefinition _fakeRelationDefinition2;
 
@@ -39,29 +39,29 @@ public override void SetUp ()
 
       _mappingObjectFactoryMock = new Mock<IMappingObjectFactory>(MockBehavior.Strict);
       _factory = new RelationDefinitionCollectionFactory(_mappingObjectFactoryMock.Object);
-      _orderClassDefinition = MappingConfiguration.Current.GetClassDefinition("Order");
-      _orderItemClassDefinition = MappingConfiguration.Current.GetClassDefinition("OrderItem");
+      _orderTypeDefinition = MappingConfiguration.Current.GetClassDefinition("Order");
+      _orderItemTypeDefinition = MappingConfiguration.Current.GetClassDefinition("OrderItem");
       _fakeRelationDefinition1 = new RelationDefinition(
           "Fake1",
-          new AnonymousRelationEndPointDefinition(_orderClassDefinition),
-          new AnonymousRelationEndPointDefinition(_orderItemClassDefinition));
+          new AnonymousRelationEndPointDefinition(_orderTypeDefinition),
+          new AnonymousRelationEndPointDefinition(_orderItemTypeDefinition));
       _fakeRelationDefinition2 = new RelationDefinition(
           "Fake2",
-          new AnonymousRelationEndPointDefinition(_orderItemClassDefinition),
-          new AnonymousRelationEndPointDefinition(_orderClassDefinition));
+          new AnonymousRelationEndPointDefinition(_orderItemTypeDefinition),
+          new AnonymousRelationEndPointDefinition(_orderTypeDefinition));
     }
 
     [Test]
     public void CreateRelationDefinitionCollection_OneClassDefinitionWithOneEndPoint ()
     {
-      var classDefinitions = new[] { _orderItemClassDefinition }.ToDictionary(cd => cd.ClassType);
+      var classDefinitions = new[] { _orderItemTypeDefinition }.ToDictionary(cd => cd.Type);
 
       _mappingObjectFactoryMock
           .Setup(
               mock => mock.CreateRelationDefinition(
                   classDefinitions,
-                  _orderItemClassDefinition,
-                  _orderItemClassDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.OrderItem.Order"].PropertyInfo))
+                  _orderItemTypeDefinition,
+                  _orderItemTypeDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.OrderItem.Order"].PropertyInfo))
           .Returns(_fakeRelationDefinition1)
           .Verifiable();
 
@@ -74,38 +74,38 @@ public void CreateRelationDefinitionCollection_OneClassDefinitionWithOneEndPoint
     [Test]
     public void CreateRelationDefinitionCollection_OneClassDefinitionWithSeveralEndPoints_DuplicatedRelationDefinitionsGetFiltered ()
     {
-      var classDefinitions = new[] { _orderClassDefinition }.ToDictionary(cd => cd.ClassType);
+      var classDefinitions = new[] { _orderTypeDefinition }.ToDictionary(cd => cd.Type);
 
       _mappingObjectFactoryMock
           .Setup(
               mock => mock.CreateRelationDefinition(
                   classDefinitions,
-                  _orderClassDefinition,
-                  _orderClassDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.Official"].PropertyInfo))
+                  _orderTypeDefinition,
+                  _orderTypeDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.Official"].PropertyInfo))
           .Returns(_fakeRelationDefinition1)
           .Verifiable();
       _mappingObjectFactoryMock
           .Setup(
               mock => mock.CreateRelationDefinition(
                   classDefinitions,
-                  _orderClassDefinition,
-                  _orderClassDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.OrderTicket"].PropertyInfo))
+                  _orderTypeDefinition,
+                  _orderTypeDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.OrderTicket"].PropertyInfo))
           .Returns(_fakeRelationDefinition1)
           .Verifiable();
       _mappingObjectFactoryMock
           .Setup(
               mock => mock.CreateRelationDefinition(
                   classDefinitions,
-                  _orderClassDefinition,
-                  _orderClassDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.Customer"].PropertyInfo))
+                  _orderTypeDefinition,
+                  _orderTypeDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.Customer"].PropertyInfo))
           .Returns(_fakeRelationDefinition2)
           .Verifiable();
       _mappingObjectFactoryMock
           .Setup(
               mock => mock.CreateRelationDefinition(
                   classDefinitions,
-                  _orderClassDefinition,
-                  _orderClassDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.OrderItems"].PropertyInfo))
+                  _orderTypeDefinition,
+                  _orderTypeDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.OrderItems"].PropertyInfo))
           .Returns(_fakeRelationDefinition2)
           .Verifiable();
 
@@ -118,46 +118,46 @@ public void CreateRelationDefinitionCollection_OneClassDefinitionWithSeveralEndP
     [Test]
     public void CreateRelationDefinitionCollection_SeveralClassDefinitionWithSeveralEndPoints_DuplicatedRelationDefinitionsGetFiltered ()
     {
-      var classDefinitions = new[] { _orderClassDefinition, _orderItemClassDefinition }.ToDictionary(cd => cd.ClassType);
+      var classDefinitions = new[] { _orderTypeDefinition, _orderItemTypeDefinition }.ToDictionary(cd => cd.Type);
 
       _mappingObjectFactoryMock
           .Setup(
               mock => mock.CreateRelationDefinition(
                   classDefinitions,
-                  _orderClassDefinition,
-                  _orderClassDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.Official"].PropertyInfo))
+                  _orderTypeDefinition,
+                  _orderTypeDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.Official"].PropertyInfo))
           .Returns(_fakeRelationDefinition1)
           .Verifiable();
       _mappingObjectFactoryMock
           .Setup(
               mock => mock.CreateRelationDefinition(
                   classDefinitions,
-                  _orderClassDefinition,
-                  _orderClassDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.OrderTicket"].PropertyInfo))
+                  _orderTypeDefinition,
+                  _orderTypeDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.OrderTicket"].PropertyInfo))
           .Returns(_fakeRelationDefinition1)
           .Verifiable();
       _mappingObjectFactoryMock
           .Setup(
               mock => mock.CreateRelationDefinition(
                   classDefinitions,
-                  _orderClassDefinition,
-                  _orderClassDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.Customer"].PropertyInfo))
+                  _orderTypeDefinition,
+                  _orderTypeDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.Customer"].PropertyInfo))
           .Returns(_fakeRelationDefinition2)
           .Verifiable();
       _mappingObjectFactoryMock
           .Setup(
               mock => mock.CreateRelationDefinition(
                   classDefinitions,
-                  _orderClassDefinition,
-                  _orderClassDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.OrderItems"].PropertyInfo))
+                  _orderTypeDefinition,
+                  _orderTypeDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.Order.OrderItems"].PropertyInfo))
           .Returns(_fakeRelationDefinition2)
           .Verifiable();
       _mappingObjectFactoryMock
           .Setup(
               mock => mock.CreateRelationDefinition(
                   classDefinitions,
-                  _orderItemClassDefinition,
-                  _orderItemClassDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.OrderItem.Order"].PropertyInfo))
+                  _orderItemTypeDefinition,
+                  _orderItemTypeDefinition.MyRelationEndPointDefinitions["Remotion.Data.DomainObjects.UnitTests.TestDomain.OrderItem.Order"].PropertyInfo))
           .Returns(_fakeRelationDefinition1)
           .Verifiable();
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionTest.cs
index 783e7badc1..26e73471e4 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionTest.cs
@@ -25,7 +25,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   [TestFixture]
   public class RelationDefinitionTest : MappingReflectionTestBase
   {
-    private ClassDefinition _customerClass;
+    private TypeDefinition _customerClass;
     private DomainObjectCollectionRelationEndPointDefinition _customerEndPoint;
     private RelationEndPointDefinition _orderEndPoint;
     private RelationDefinition _customerToOrder;
@@ -67,10 +67,10 @@ public void IsEndPoint ()
     {
       RelationDefinition relation = new RelationDefinition("myRelation", _customerEndPoint, _orderEndPoint);
 
-      Assert.That(relation.IsEndPoint("Order", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.Customer"), Is.True);
-      Assert.That(relation.IsEndPoint("Customer", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders"), Is.True);
-      Assert.That(relation.IsEndPoint("Order", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders"), Is.False);
-      Assert.That(relation.IsEndPoint("Customer", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.Customer"), Is.False);
+      Assert.That(relation.IsEndPoint(typeof(Order), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.Customer"), Is.True);
+      Assert.That(relation.IsEndPoint(typeof(Customer), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders"), Is.True);
+      Assert.That(relation.IsEndPoint(typeof(Order), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders"), Is.False);
+      Assert.That(relation.IsEndPoint(typeof(Customer), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.Customer"), Is.False);
     }
 
     [Test]
@@ -89,21 +89,21 @@ public void Contains ()
     public void GetEndPointDefinition ()
     {
       Assert.That(
-          _customerToOrder.GetEndPointDefinition("Order", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.Customer"),
+          _customerToOrder.GetEndPointDefinition(typeof(Order), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.Customer"),
           Is.SameAs(_orderEndPoint));
       Assert.That(_customerToOrder.GetEndPointDefinition(
-          "Customer", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders"), Is.SameAs(_customerEndPoint));
+          typeof(Customer), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders"), Is.SameAs(_customerEndPoint));
     }
 
     [Test]
     public void GetOppositeEndPointDefinition_Strings ()
     {
       var result1 = _customerToOrder.GetOppositeEndPointDefinition(
-          "Order", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.Customer");
+          typeof(Order), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.Customer");
       Assert.That(result1, Is.SameAs(_customerEndPoint));
 
       var result2 = _customerToOrder.GetOppositeEndPointDefinition(
-          "Customer", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders");
+          typeof(Customer), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders");
       Assert.That(result2, Is.SameAs(_orderEndPoint));
     }
 
@@ -111,7 +111,7 @@ public void GetOppositeEndPointDefinition_Strings ()
     public void GetOppositeEndPointDefinitionForUndefinedProperty_Strings ()
     {
       var result = _customerToOrder.GetOppositeEndPointDefinition(
-          "Order", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.OrderNumber");
+          typeof(Order), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.OrderNumber");
       Assert.That(result, Is.Null);
     }
 
@@ -138,7 +138,7 @@ public void GetOppositeEndPointDefinitionForUndefinedProperty_EndPoint ()
     public void GetEndPointDefinitionForUndefinedProperty ()
     {
       var result = _customerToOrder.GetEndPointDefinition(
-          "Order", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.OrderNumber");
+          typeof(Order), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.OrderNumber");
       Assert.That(result, Is.Null);
     }
 
@@ -147,14 +147,14 @@ public void GetEndPointDefinitionForUndefinedProperty ()
     public void GetEndPointDefinitionForUndefinedClass ()
     {
       Assert.That(_customerToOrder.GetEndPointDefinition(
-          "OrderTicket", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.OrderTicket.Customer"), Is.Null);
+          typeof(OrderTicket), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.OrderTicket.Customer"), Is.Null);
     }
 
     [Test]
     public void GetOppositeEndPointDefinitionForUndefinedClass ()
     {
       Assert.That(_customerToOrder.GetOppositeEndPointDefinition(
-          "OrderTicket", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.OrderTicket.Customer"), Is.Null);
+          typeof(OrderTicket), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.OrderTicket.Customer"), Is.Null);
     }
 
 
@@ -175,7 +175,8 @@ public void GetMandatoryOppositeRelationEndPointDefinitionWithNotAssociatedRelat
               .With.Message.EqualTo(
                   "Relation 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.OrderItem:"
                   + "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.OrderItem.Order->"
-                  +"Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.OrderItems' has no association with class 'Customer' "
+                  +"Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.OrderItems' has no association with type "
+                  + "'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer' "
                   + "and property 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders'."));
     }
 
@@ -206,7 +207,7 @@ public void RelationType_Unidirectional ()
     private IRelationEndPointDefinition CreateEquivalentEndPointDefinitionFake (DomainObjectCollectionRelationEndPointDefinition sourceEndPoint)
     {
       var invalidEndPoint = new Mock<IRelationEndPointDefinition>();
-      invalidEndPoint.Setup(stub => stub.ClassDefinition).Returns(sourceEndPoint.ClassDefinition);
+      invalidEndPoint.Setup(stub => stub.TypeDefinition).Returns(sourceEndPoint.TypeDefinition);
       invalidEndPoint.Setup(stub => stub.PropertyName).Returns(sourceEndPoint.PropertyName);
       return invalidEndPoint.Object;
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionWithAnonymousRelationEndPointTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionWithAnonymousRelationEndPointTest.cs
index d8be8c33eb..e9d8770f4c 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionWithAnonymousRelationEndPointTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationDefinitionWithAnonymousRelationEndPointTest.cs
@@ -17,6 +17,7 @@
 using System;
 using NUnit.Framework;
 using Remotion.Data.DomainObjects.Mapping;
+using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration;
 
 namespace Remotion.Data.DomainObjects.UnitTests.Mapping
 {
@@ -42,19 +43,19 @@ public override void SetUp ()
     public void GetOppositeEndPointDefinition ()
     {
       Assert.That(
-          _relation.GetOppositeEndPointDefinition("Location", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Location.Client"),
+          _relation.GetOppositeEndPointDefinition(typeof(Location), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Location.Client"),
           Is.SameAs(_clientEndPoint));
-      Assert.That(_relation.GetOppositeEndPointDefinition("Client", null), Is.SameAs(_locationEndPoint));
+      Assert.That(_relation.GetOppositeEndPointDefinition(typeof(Client), null), Is.SameAs(_locationEndPoint));
     }
 
     [Test]
     public void IsEndPoint ()
     {
-      Assert.That(_relation.IsEndPoint("Location", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Location.Client"), Is.True);
-      Assert.That(_relation.IsEndPoint("Client", null), Is.True);
+      Assert.That(_relation.IsEndPoint(typeof(Location), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Location.Client"), Is.True);
+      Assert.That(_relation.IsEndPoint(typeof(Client), null), Is.True);
 
-      Assert.That(_relation.IsEndPoint("Location", null), Is.False);
-      Assert.That(_relation.IsEndPoint("Client", "Client"), Is.False);
+      Assert.That(_relation.IsEndPoint(typeof(Location), null), Is.False);
+      Assert.That(_relation.IsEndPoint(typeof(Client), "Client"), Is.False);
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionChecker.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionChecker.cs
index f86eefa629..2d5a16c8b7 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionChecker.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionChecker.cs
@@ -44,9 +44,10 @@ public void Check (
           "End point definitions (property name: '{0}') are not of same type.",
           expectedEndPointDefinition.PropertyName);
 
+      // TODO R2I Mapping: Do actually checking for TypeDefinition not only ClassDefinition
       Assert.AreEqual(
-          expectedEndPointDefinition.ClassDefinition.ID,
-          actualEndPointDefinition.ClassDefinition.ID,
+          ((ClassDefinition)expectedEndPointDefinition.TypeDefinition).ID,
+          ((ClassDefinition)actualEndPointDefinition.TypeDefinition).ID,
           "ClassDefinition of end point definitions (property name: '{0}') does not match.",
           expectedEndPointDefinition.PropertyName);
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionCollectionFactoryTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionCollectionFactoryTest.cs
index 229e983f34..3b9838f9c4 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionCollectionFactoryTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionCollectionFactoryTest.cs
@@ -45,19 +45,19 @@ public void SetUp ()
     [Test]
     public void CreateRelationEndPointDefinitionCollection ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(OrderTicket));
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(classDefinition);
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(OrderTicket));
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(typeDefinition);
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
       var fakeRelationEndPoint = new RelationEndPointDefinition(propertyDefinition, false);
 
       var expectedPropertyInfo = PropertyInfoAdapter.Create(typeof(OrderTicket).GetProperty("Order"));
 
       _mappingObjectFactoryMock
-          .Setup(mock => mock.CreateRelationEndPointDefinition(classDefinition, PropertyInfoAdapter.Create(expectedPropertyInfo.PropertyInfo)))
+          .Setup(mock => mock.CreateRelationEndPointDefinition(typeDefinition, PropertyInfoAdapter.Create(expectedPropertyInfo.PropertyInfo)))
           .Returns(fakeRelationEndPoint)
           .Verifiable();
 
-      var result = _factory.CreateRelationEndPointDefinitionCollection(classDefinition);
+      var result = _factory.CreateRelationEndPointDefinitionCollection(typeDefinition);
 
       _mappingObjectFactoryMock.Verify();
       _memberInformationNameResolverMock.Verify();
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionCollectionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionCollectionTest.cs
index 395dd9cb6d..ca73e8d9d9 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionCollectionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionCollectionTest.cs
@@ -27,7 +27,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   public class RelationEndPointDefinitionCollectionTest : MappingReflectionTestBase
   {
     private RelationEndPointDefinitionCollection _collection;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
     private RelationEndPointDefinition _endPoint1;
     private RelationEndPointDefinition _endPoint2;
     private AnonymousRelationEndPointDefinition _anonymousEndPoint;
@@ -36,25 +36,25 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
-      var propertyDefinition1 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(_classDefinition, "Property1");
-      var propertyDefinition2 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(_classDefinition, "Property2");
-      var propertyDefinition3 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(_classDefinition, "Property3");
-      var propertyDefinition4 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(_classDefinition, "Property4");
-      _classDefinition.SetPropertyDefinitions(
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition();
+      var propertyDefinition1 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(_typeDefinition, "Property1");
+      var propertyDefinition2 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(_typeDefinition, "Property2");
+      var propertyDefinition3 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(_typeDefinition, "Property3");
+      var propertyDefinition4 = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(_typeDefinition, "Property4");
+      _typeDefinition.SetPropertyDefinitions(
           new PropertyDefinitionCollection(new[] { propertyDefinition1, propertyDefinition2, propertyDefinition3, propertyDefinition4 }, true));
       _endPoint1 = new RelationEndPointDefinition(propertyDefinition1, false);
       _endPoint2 = new RelationEndPointDefinition(propertyDefinition2, false);
-      _anonymousEndPoint = new AnonymousRelationEndPointDefinition(_classDefinition);
+      _anonymousEndPoint = new AnonymousRelationEndPointDefinition(_typeDefinition);
       _collection = new RelationEndPointDefinitionCollection();
     }
 
     [Test]
     public void CreateForAllRelationEndPoints_ClassDefinitionWithoutBaseClassDefinition_MakeCollectionReadOnlyIsFalse ()
     {
-      _classDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { _endPoint1, _endPoint2 }, true));
+      _typeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { _endPoint1, _endPoint2 }, true));
 
-      var endPoints = RelationEndPointDefinitionCollection.CreateForAllRelationEndPoints(_classDefinition, false);
+      var endPoints = RelationEndPointDefinitionCollection.CreateForAllRelationEndPoints(_typeDefinition, false);
 
       Assert.That(endPoints.Count, Is.EqualTo(2));
       Assert.That(endPoints.IsReadOnly, Is.False);
@@ -65,9 +65,9 @@ public void CreateForAllRelationEndPoints_ClassDefinitionWithoutBaseClassDefinit
     [Test]
     public void CreateForAllRelationEndPoints_ClassDefinitionWithoutBaseClassDefinition_MakeCollectionReadOnlyIsTrue ()
     {
-      _classDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { _endPoint1, _endPoint2 }, false));
+      _typeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { _endPoint1, _endPoint2 }, false));
 
-      var endPoints = RelationEndPointDefinitionCollection.CreateForAllRelationEndPoints(_classDefinition, true);
+      var endPoints = RelationEndPointDefinitionCollection.CreateForAllRelationEndPoints(_typeDefinition, true);
 
       Assert.That(endPoints.Count, Is.EqualTo(2));
       Assert.That(endPoints.IsReadOnly, Is.True);
@@ -81,7 +81,7 @@ public void CreateForAllRelationEndPoints_ClassDefinitionWithBaseClassDefinition
       var baseClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Company));
       var basedPropertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(baseClassDefinition, "Property1");
       baseClassDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { basedPropertyDefinition }, true));
-      var derivedClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Partner), baseClass: baseClassDefinition);
+      var derivedClassDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Partner), baseClass: baseClassDefinition);
       var derivedPropertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(derivedClassDefinition, "Property2");
       derivedClassDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { derivedPropertyDefinition }, true));
 
@@ -98,6 +98,33 @@ public void CreateForAllRelationEndPoints_ClassDefinitionWithBaseClassDefinition
       Assert.That(endPoints[1], Is.SameAs(endPoint1));
     }
 
+    [Test]
+    public void CreateForAllRelationEndPoints_ClassDefinitionWithImplementedInterfaces ()
+    {
+      var iPerson = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      var iCustomer = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(extendedInterfaces: new[] { iPerson });
+      var customer = ClassDefinitionObjectMother.CreateClassDefinition(implementedInterfaces: new[] { iCustomer });
+
+      var propertyDefinitionInIPerson = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(iPerson, "A");
+      var propertyDefinitionInICustomer = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(iCustomer, "B");
+      var propertyDefinitionInCustomer = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(customer, "C");
+
+      var endPointInIPerson = new RelationEndPointDefinition(propertyDefinitionInIPerson, false);
+      var endPointInICustomer = new RelationEndPointDefinition(propertyDefinitionInICustomer, false);
+      var endPointInCustomer = new RelationEndPointDefinition(propertyDefinitionInCustomer, false);
+
+      iPerson.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPointInIPerson }, true));
+      iCustomer.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPointInICustomer }, true));
+      customer.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPointInCustomer }, true));
+
+      var relationEndPoints = RelationEndPointDefinitionCollection.CreateForAllRelationEndPoints(customer, false);
+
+      Assert.That(relationEndPoints.Count, Is.EqualTo(3));
+      Assert.That(relationEndPoints[0], Is.SameAs(endPointInCustomer));
+      Assert.That(relationEndPoints[1], Is.SameAs(endPointInICustomer));
+      Assert.That(relationEndPoints[2], Is.SameAs(endPointInIPerson));
+    }
+
     [Test]
     public void Add ()
     {
@@ -108,7 +135,7 @@ public void Add ()
     [Test]
     public void Add_PropertyNameIsNull ()
     {
-      var endPoint = new AnonymousRelationEndPointDefinition(_classDefinition);
+      var endPoint = new AnonymousRelationEndPointDefinition(_typeDefinition);
       Assert.That(
           () => _collection.Add(endPoint),
           Throws.ArgumentException.With.ArgumentExceptionMessageEqualTo("Anonymous end points cannot be added to this collection.", "value"));
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionExtensionsTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionExtensionsTest.cs
index a85c224d50..56934905ff 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionExtensionsTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionExtensionsTest.cs
@@ -43,7 +43,7 @@ public void GetOppositeClassDefinition ()
       var endPointDefinition = DomainObjectIDs.Order1.ClassDefinition.GetMandatoryRelationEndPointDefinition(
           typeof(Order).FullName + ".OrderTicket");
 
-      var oppositeEndPointDefinition = endPointDefinition.GetOppositeClassDefinition();
+      var oppositeEndPointDefinition = endPointDefinition.GetOppositeTypeDefinition();
 
       Assert.That(oppositeEndPointDefinition, Is.SameAs(DomainObjectIDs.OrderTicket1.ClassDefinition));
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionTest.cs
index 4a24c8a83b..8096946e62 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointDefinitionTest.cs
@@ -37,10 +37,10 @@ public override void SetUp ()
         + "Integration.Customer.Orders"];
 
       _customerEndPoint = (DomainObjectCollectionRelationEndPointDefinition)customerToOrder.GetEndPointDefinition(
-          "Customer", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders");
+          typeof(Customer), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Customer.Orders");
 
       _orderEndPoint = (RelationEndPointDefinition)customerToOrder.GetEndPointDefinition(
-          "Order", "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.Customer");
+          typeof(Order), "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order.Customer");
     }
 
     [Test]
@@ -52,16 +52,17 @@ public void Initialization_PropertyOfWrongType ()
           () => new RelationEndPointDefinition(propertyDefinition, false),
           Throws.InstanceOf<MappingException>()
               .With.Message.EqualTo(
-                  "Relation definition error: Property 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Company.Name' of class 'Company' is of type "
+                  "Relation definition error: Property 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Company.Name' of type "
+                  + "'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Company' is of type "
                   + "'System.String', but non-virtual properties must be of type 'Remotion.Data.DomainObjects.ObjectID'."));
     }
 
     [Test]
     public void Initialize ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order));
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(classDefinition);
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection { propertyDefinition });
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order));
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(typeDefinition);
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection { propertyDefinition });
       var endPoint = new RelationEndPointDefinition(propertyDefinition, true);
 
       Assert.That(endPoint.PropertyInfo, Is.SameAs(propertyDefinition.PropertyInfo));
@@ -76,8 +77,8 @@ public void IsAnonymous ()
     [Test]
     public void RelationDefinition_NotSet ()
     {
-      var classDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(OrderTicket)];
-      var propertyDefinition = classDefinition["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.OrderTicket.Order"];
+      var typeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(OrderTicket)];
+      var propertyDefinition = typeDefinition["Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.OrderTicket.Order"];
 
       var definition = new RelationEndPointDefinition(propertyDefinition, true);
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/BaseManySideRelationProperty.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/BaseManySideRelationProperty.cs
index 55ce8c0257..34b3f694d9 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/BaseManySideRelationProperty.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/BaseManySideRelationProperty.cs
@@ -28,13 +28,13 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.RelationEndPointReflecto
   [TestFixture]
   public class BaseManySideRelationProperty : MappingReflectionTestBase
   {
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     public override void SetUp ()
     {
       base.SetUp();
 
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
     }
 
     [Test]
@@ -50,7 +50,7 @@ public void GetMetadata_Unidirectional ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("BaseUnidirectional")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -68,7 +68,7 @@ public void GetMetadata_BidirectionalOneToOne ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("BaseBidirectionalOneToOne")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -86,7 +86,7 @@ public void GetMetadata_BidirectionalOneToManyForDomainObjectCollection ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("BaseBidirectionalOneToManyForDomainObjectCollection")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -104,7 +104,7 @@ public void GetMetadata_BidirectionalOneToManyForVirtualCollection ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("BaseBidirectionalOneToManyForVirtualCollection")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -145,10 +145,10 @@ private RdbmsRelationEndPointReflector CreateRelationEndPointReflector (string p
     {
       PropertyReflector propertyReflector = CreatePropertyReflector(propertyName);
       PropertyDefinition propertyDefinition = propertyReflector.GetMetadata();
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
 
       return new RdbmsRelationEndPointReflector(
-          _classDefinition,
+          _typeDefinition,
           propertyReflector.PropertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -163,7 +163,7 @@ private PropertyReflector CreatePropertyReflector (string property)
           PropertyInfoAdapter.Create(type.GetProperty(property, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic));
 
       return new PropertyReflector(
-          _classDefinition,
+          _typeDefinition,
           propertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -173,7 +173,7 @@ private PropertyReflector CreatePropertyReflector (string property)
 
     private PropertyDefinition GetPropertyDefinition (string propertyName)
     {
-      return _classDefinition.MyPropertyDefinitions[
+      return _typeDefinition.MyPropertyDefinitions[
           string.Format("{0}.{1}", typeof(ClassWithRealRelationEndPointsNotInMapping).FullName, propertyName)];
     }
   }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/BaseOneSideRelationProperty.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/BaseOneSideRelationProperty.cs
index 9c897aac29..89ebc4acc8 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/BaseOneSideRelationProperty.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/BaseOneSideRelationProperty.cs
@@ -29,7 +29,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.RelationEndPointReflecto
   [TestFixture]
   public class BaseOneSideRelationProperty : MappingReflectionTestBase
   {
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
     private Type _classType;
 
     public override void SetUp ()
@@ -37,7 +37,7 @@ public override void SetUp ()
       base.SetUp();
 
       _classType = typeof(ClassWithVirtualRelationEndPoints);
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: _classType);
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: _classType);
     }
 
     [Test]
@@ -54,7 +54,7 @@ public void GetMetadata_BidirectionalOneToOne ()
 
       Assert.IsInstanceOf(typeof(VirtualObjectRelationEndPointDefinition), actual);
       VirtualObjectRelationEndPointDefinition relationEndPointDefinition = (VirtualObjectRelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(
           relationEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -71,7 +71,7 @@ public void GetMetadata_BidirectionalOneToManyForDomainObjectCollection ()
           .Setup(stub => stub.IsNullable(It.Is<IPropertyInformation>(pi => pi.Name == "BaseBidirectionalOneToManyForDomainObjectCollection")))
           .Returns(true);
       SortExpressionDefinitionProviderStub
-          .Setup(stub => stub.GetSortExpression(It.IsAny<IPropertyInformation>(), It.IsAny<ClassDefinition>(), It.IsAny<string>()))
+          .Setup(stub => stub.GetSortExpression(It.IsAny<IPropertyInformation>(), It.IsAny<TypeDefinition>(), It.IsAny<string>()))
           .Throws(new InvalidOperationException("GetSortExpression() should not be called during GetMetadata()"));
 
       var propertyInfo = PropertyInfoAdapter.Create(_classType.GetProperty("BaseBidirectionalOneToManyForDomainObjectCollection"));
@@ -81,7 +81,7 @@ public void GetMetadata_BidirectionalOneToManyForDomainObjectCollection ()
 
       Assert.IsInstanceOf(typeof(DomainObjectCollectionRelationEndPointDefinition), actual);
       DomainObjectCollectionRelationEndPointDefinition relationEndPointDefinition = (DomainObjectCollectionRelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(
           relationEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -90,19 +90,19 @@ public void GetMetadata_BidirectionalOneToManyForDomainObjectCollection ()
       Assert.That(relationEndPointDefinition.Cardinality, Is.EqualTo(CardinalityType.Many));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
 
-      var oppositeClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
+      var oppositeTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
       var oppositeEndPointDefinition = new Mock<IRelationEndPointDefinition>();
-      oppositeEndPointDefinition.Setup(stub => stub.ClassDefinition).Returns(oppositeClassDefinition);
+      oppositeEndPointDefinition.Setup(stub => stub.TypeDefinition).Returns(oppositeTypeDefinition);
       var relationDefinition = new RelationDefinition("relation", relationEndPointDefinition, oppositeEndPointDefinition.Object);
       relationEndPointDefinition.SetRelationDefinition(relationDefinition);
       var oppositePropertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(
-          oppositeClassDefinition,
-          oppositeClassDefinition.ClassType,
+          oppositeTypeDefinition,
+          oppositeTypeDefinition.Type,
           "NoAttributeForDomainObjectCollection");
       var sortExpressionDefinition = new SortExpressionDefinition(new[] { SortExpressionDefinitionObjectMother.CreateSortedPropertyAscending(oppositePropertyDefinition) });
       SortExpressionDefinitionProviderStub.Reset();
       SortExpressionDefinitionProviderStub
-          .Setup(stub => stub.GetSortExpression(relationEndPointDefinition.PropertyInfo, oppositeClassDefinition, "NoAttributeForDomainObjectCollection"))
+          .Setup(stub => stub.GetSortExpression(relationEndPointDefinition.PropertyInfo, oppositeTypeDefinition, "NoAttributeForDomainObjectCollection"))
           .Returns(sortExpressionDefinition);
 
       Assert.That(relationEndPointDefinition.GetSortExpression(), Is.SameAs(sortExpressionDefinition));
@@ -115,7 +115,7 @@ public void GetMetadata_BidirectionalOneToManyForVirtualCollection ()
           .Setup(stub => stub.IsNullable(It.Is<IPropertyInformation>(pi => pi.Name == "BaseBidirectionalOneToManyForVirtualCollection")))
           .Returns(true);
       SortExpressionDefinitionProviderStub
-          .Setup(stub => stub.GetSortExpression(It.IsAny<IPropertyInformation>(), It.IsAny<ClassDefinition>(), It.IsAny<string>()))
+          .Setup(stub => stub.GetSortExpression(It.IsAny<IPropertyInformation>(), It.IsAny<TypeDefinition>(), It.IsAny<string>()))
           .Throws(new InvalidOperationException("GetSortExpression() should not be called during GetMetadata()"));
 
       var propertyInfo = PropertyInfoAdapter.Create(_classType.GetProperty("BaseBidirectionalOneToManyForVirtualCollection"));
@@ -125,7 +125,7 @@ public void GetMetadata_BidirectionalOneToManyForVirtualCollection ()
 
       Assert.IsInstanceOf(typeof(VirtualCollectionRelationEndPointDefinition), actual);
       VirtualCollectionRelationEndPointDefinition relationEndPointDefinition = (VirtualCollectionRelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(
           relationEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -134,19 +134,19 @@ public void GetMetadata_BidirectionalOneToManyForVirtualCollection ()
       Assert.That(relationEndPointDefinition.Cardinality, Is.EqualTo(CardinalityType.Many));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
 
-      var oppositeClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
+      var oppositeTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
       var oppositeEndPointDefinition = new Mock<IRelationEndPointDefinition>();
-      oppositeEndPointDefinition.Setup(stub => stub.ClassDefinition).Returns(oppositeClassDefinition);
+      oppositeEndPointDefinition.Setup(stub => stub.TypeDefinition).Returns(oppositeTypeDefinition);
       var relationDefinition = new RelationDefinition("relation", relationEndPointDefinition, oppositeEndPointDefinition.Object);
       relationEndPointDefinition.SetRelationDefinition(relationDefinition);
       var oppositePropertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(
-          oppositeClassDefinition,
-          oppositeClassDefinition.ClassType,
+          oppositeTypeDefinition,
+          oppositeTypeDefinition.Type,
           "NoAttributeForVirtualCollection");
       var sortExpressionDefinition = new SortExpressionDefinition(new[] { SortExpressionDefinitionObjectMother.CreateSortedPropertyAscending(oppositePropertyDefinition) });
       SortExpressionDefinitionProviderStub.Reset();
       SortExpressionDefinitionProviderStub
-          .Setup(stub => stub.GetSortExpression(relationEndPointDefinition.PropertyInfo, oppositeClassDefinition, "NoAttributeForVirtualCollection"))
+          .Setup(stub => stub.GetSortExpression(relationEndPointDefinition.PropertyInfo, oppositeTypeDefinition, "NoAttributeForVirtualCollection"))
           .Returns(sortExpressionDefinition);
 
       Assert.That(relationEndPointDefinition.GetSortExpression(), Is.SameAs(sortExpressionDefinition));
@@ -182,7 +182,7 @@ public void IsVirtualEndRelationEndpoint_BidirectionalOneToManyForVirtualCollect
     private RdbmsRelationEndPointReflector CreateRelationEndPointReflector (PropertyInfoAdapter propertyInfo)
     {
       return new RdbmsRelationEndPointReflector(
-          _classDefinition,
+          _typeDefinition,
           propertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/Common.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/Common.cs
index 0dbb427e16..40526fc6f4 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/Common.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/Common.cs
@@ -36,7 +36,7 @@ public void CreateRelationEndPointReflector ()
       Assert.IsInstanceOf(
           typeof(RdbmsRelationEndPointReflector),
           RelationEndPointReflector.CreateRelationEndPointReflector(
-              ClassDefinitionObjectMother.CreateClassDefinition(classType: type),
+              TypeDefinitionObjectMother.CreateClassDefinition(classType: type),
               propertyInfo,
               Configuration.NameResolver,
               PropertyMetadataProvider,
@@ -50,7 +50,7 @@ public void IsVirtualEndRelationEndpoint_WithoutAttribute ()
       var type = typeof(ClassWithRealRelationEndPoints);
       var propertyInfo = PropertyInfoAdapter.Create(type.GetProperty("NoAttributeForDomainObjectCollection"));
       var relationEndPointReflector = RelationEndPointReflector.CreateRelationEndPointReflector(
-          ClassDefinitionObjectMother.CreateClassDefinition(classType: type),
+          TypeDefinitionObjectMother.CreateClassDefinition(classType: type),
           propertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -66,7 +66,7 @@ public void IsVirtualEndRelationEndpoint_WithDomainObjectCollectionPropertyAndWi
       var type = typeof(ClassWithInvalidUnidirectionalRelation);
       var propertyInfo = PropertyInfoAdapter.Create(type.GetProperty("LeftSideForDomainObjectCollection"));
       var relationEndPointReflector = RelationEndPointReflector.CreateRelationEndPointReflector(
-          ClassDefinitionObjectMother.CreateClassDefinition(classType: type),
+          TypeDefinitionObjectMother.CreateClassDefinition(classType: type),
           propertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -82,7 +82,7 @@ public void IsVirtualEndRelationEndpoint_WithVirtualCollectionPropertyAndWithout
       var type = typeof(ClassWithInvalidUnidirectionalRelation);
       var propertyInfo = PropertyInfoAdapter.Create(type.GetProperty("LeftSideForVirtualCollection"));
       var relationEndPointReflector = RelationEndPointReflector.CreateRelationEndPointReflector(
-          ClassDefinitionObjectMother.CreateClassDefinition(classType: type),
+          TypeDefinitionObjectMother.CreateClassDefinition(classType: type),
           propertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -98,7 +98,7 @@ public void IsVirtualRelationEndPoint_UnidirectionalRelation ()
       var type = typeof(ClassWithRealRelationEndPoints);
       var propertyInfo = PropertyInfoAdapter.Create(type.GetProperty("Unidirectional"));
       var relationEndPointReflector = new RdbmsRelationEndPointReflector(
-          ClassDefinitionObjectMother.CreateClassDefinition(classType: type),
+          TypeDefinitionObjectMother.CreateClassDefinition(classType: type),
           propertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -111,16 +111,16 @@ public void IsVirtualRelationEndPoint_UnidirectionalRelation ()
     [Test]
     public void GetMetadata_NonVirtualEndPoint_PropertyTypeIsNotObjectID ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithRealRelationEndPoints));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithRealRelationEndPoints));
       var propertyDefinition =
-          PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition, "Unidirectional", typeof(string));
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+          PropertyDefinitionObjectMother.CreateForFakePropertyInfo(typeDefinition, "Unidirectional", typeof(string));
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
 
       var mappingNameResolverMock = new Mock<IMemberInformationNameResolver>();
       mappingNameResolverMock.Setup(mock => mock.GetPropertyName(propertyDefinition.PropertyInfo)).Returns(propertyDefinition.PropertyName);
 
       var relationEndPointReflector = RelationEndPointReflector.CreateRelationEndPointReflector(
-          classDefinition,
+          typeDefinition,
           propertyDefinition.PropertyInfo,
           mappingNameResolverMock.Object,
           PropertyMetadataProvider,
@@ -135,16 +135,16 @@ public void GetMetadata_NonVirtualEndPoint_PropertyTypeIsNotObjectID ()
     [Test]
     public void GetMetadata_VirtualEndPoint_PropertyTypeIsNotCompatible ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithVirtualRelationEndPoints));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithVirtualRelationEndPoints));
       var propertyDefinition =
-          PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition, "BidirectionalOneToManyForDomainObjectCollection", typeof(string));
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+          PropertyDefinitionObjectMother.CreateForFakePropertyInfo(typeDefinition, "BidirectionalOneToManyForDomainObjectCollection", typeof(string));
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
 
       var mappingNameResolverMock = new Mock<IMemberInformationNameResolver>();
       mappingNameResolverMock.Setup(mock => mock.GetPropertyName(propertyDefinition.PropertyInfo)).Returns(propertyDefinition.PropertyName);
 
       var relationEndPointReflectorPartialMock = new Mock<RelationEndPointReflector<BidirectionalRelationAttribute>>(
-          classDefinition,
+          typeDefinition,
           propertyDefinition.PropertyInfo,
           mappingNameResolverMock.Object,
           PropertyMetadataProvider,
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/GenericManySideRelationProperty.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/GenericManySideRelationProperty.cs
index 89020bd8ea..0514c474f5 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/GenericManySideRelationProperty.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/GenericManySideRelationProperty.cs
@@ -28,13 +28,13 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.RelationEndPointReflecto
   [TestFixture]
   public class GenericManySideRelationProperty : MappingReflectionTestBase
   {
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     public override void SetUp ()
     {
       base.SetUp();
 
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClosedGenericClassWithRealRelationEndPoints));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClosedGenericClassWithRealRelationEndPoints));
     }
 
     [Test]
@@ -50,7 +50,7 @@ public void GetMetadata_Unidirectional ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("BaseUnidirectional")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -68,7 +68,7 @@ public void GetMetadata_BidirectionalOneToOne ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("BaseBidirectionalOneToOne")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -86,7 +86,7 @@ public void GetMetadata_BidirectionalOneToMany ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("BaseBidirectionalOneToMany")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -120,10 +120,10 @@ private RdbmsRelationEndPointReflector CreateRelationEndPointReflector (string p
     {
       PropertyReflector propertyReflector = CreatePropertyReflector(propertyName);
       PropertyDefinition propertyDefinition = propertyReflector.GetMetadata();
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
 
       return new RdbmsRelationEndPointReflector(
-          _classDefinition,
+          _typeDefinition,
           propertyReflector.PropertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -138,7 +138,7 @@ private PropertyReflector CreatePropertyReflector (string property)
           PropertyInfoAdapter.Create(type.GetProperty(property, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic));
 
       return new PropertyReflector(
-          _classDefinition,
+          _typeDefinition,
           propertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -148,7 +148,7 @@ private PropertyReflector CreatePropertyReflector (string property)
 
     private PropertyDefinition GetPropertyDefinition (string propertyName)
     {
-      return _classDefinition.MyPropertyDefinitions[
+      return _typeDefinition.MyPropertyDefinitions[
           string.Format("{0}.{1}", typeof(GenericClassWithRealRelationEndPointsNotInMapping<>).FullName, propertyName)];
     }
   }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/ManySideRelationPropertyForDomainObjectCollection.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/ManySideRelationPropertyForDomainObjectCollection.cs
index 1baf37f6e2..9dac138a8f 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/ManySideRelationPropertyForDomainObjectCollection.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/ManySideRelationPropertyForDomainObjectCollection.cs
@@ -28,7 +28,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.RelationEndPointReflecto
   [TestFixture]
   public class ManySideRelationPropertyForDomainObjectCollection : MappingReflectionTestBase
   {
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
     private Type _classType;
 
     public override void SetUp ()
@@ -36,7 +36,7 @@ public override void SetUp ()
       base.SetUp();
 
       _classType = typeof(ClassWithRealRelationEndPoints);
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: _classType);
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: _classType);
     }
 
     [Test]
@@ -82,7 +82,7 @@ public void GetMetadata_Unidirectional ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("Unidirectional")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -100,7 +100,7 @@ public void GetMetadata_BidirectionalOneToOne ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("BidirectionalOneToOne")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -118,7 +118,7 @@ public void GetMetadata_BidirectionalOneToMany ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("BidirectionalOneToManyForDomainObjectCollection")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -151,10 +151,10 @@ private RdbmsRelationEndPointReflector CreateRelationEndPointReflector (string p
     {
       PropertyReflector propertyReflector = CreatePropertyReflector(propertyName);
       PropertyDefinition propertyDefinition = propertyReflector.GetMetadata();
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
 
       return new RdbmsRelationEndPointReflector(
-          _classDefinition,
+          _typeDefinition,
           propertyReflector.PropertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -168,7 +168,7 @@ private PropertyReflector CreatePropertyReflector (string property)
           PropertyInfoAdapter.Create(_classType.GetProperty(property, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic));
 
       return new PropertyReflector(
-          _classDefinition,
+          _typeDefinition,
           propertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -178,7 +178,7 @@ private PropertyReflector CreatePropertyReflector (string property)
 
     private PropertyDefinition GetPropertyDefinition (string propertyName)
     {
-      return _classDefinition.MyPropertyDefinitions[string.Format("{0}.{1}", _classType.FullName, propertyName)];
+      return _typeDefinition.MyPropertyDefinitions[string.Format("{0}.{1}", _classType.FullName, propertyName)];
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/ManySideRelationPropertyForVirtualCollection.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/ManySideRelationPropertyForVirtualCollection.cs
index fb4247263c..39749d1792 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/ManySideRelationPropertyForVirtualCollection.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/ManySideRelationPropertyForVirtualCollection.cs
@@ -28,7 +28,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.RelationEndPointReflecto
   [TestFixture]
   public class ManySideRelationPropertyForVirtualCollection : MappingReflectionTestBase
   {
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
     private Type _classType;
 
     public override void SetUp ()
@@ -36,7 +36,7 @@ public override void SetUp ()
       base.SetUp();
 
       _classType = typeof(ClassWithRealRelationEndPoints);
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: _classType);
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: _classType);
     }
 
     [Test]
@@ -82,7 +82,7 @@ public void GetMetadata_Unidirectional ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("Unidirectional")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -100,7 +100,7 @@ public void GetMetadata_BidirectionalOneToOne ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("BidirectionalOneToOne")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -118,7 +118,7 @@ public void GetMetadata_BidirectionalOneToMany ()
 
       Assert.IsInstanceOf(typeof(RelationEndPointDefinition), actual);
       RelationEndPointDefinition relationEndPointDefinition = (RelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(relationEndPointDefinition.PropertyDefinition, Is.SameAs(GetPropertyDefinition("BidirectionalOneToManyForVirtualCollection")));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
     }
@@ -151,10 +151,10 @@ private RdbmsRelationEndPointReflector CreateRelationEndPointReflector (string p
     {
       PropertyReflector propertyReflector = CreatePropertyReflector(propertyName);
       PropertyDefinition propertyDefinition = propertyReflector.GetMetadata();
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
 
       return new RdbmsRelationEndPointReflector(
-          _classDefinition,
+          _typeDefinition,
           propertyReflector.PropertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -168,7 +168,7 @@ private PropertyReflector CreatePropertyReflector (string property)
           PropertyInfoAdapter.Create(_classType.GetProperty(property, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic));
 
       return new PropertyReflector(
-          _classDefinition,
+          _typeDefinition,
           propertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
@@ -178,7 +178,7 @@ private PropertyReflector CreatePropertyReflector (string property)
 
     private PropertyDefinition GetPropertyDefinition (string propertyName)
     {
-      return _classDefinition.MyPropertyDefinitions[string.Format("{0}.{1}", _classType.FullName, propertyName)];
+      return _typeDefinition.MyPropertyDefinitions[string.Format("{0}.{1}", _classType.FullName, propertyName)];
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/OneSideRelationProperty.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/OneSideRelationProperty.cs
index 4093c1020e..94e0dd59d7 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/OneSideRelationProperty.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationEndPointReflectorTests/OneSideRelationProperty.cs
@@ -29,7 +29,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.RelationEndPointReflecto
   [TestFixture]
   public class OneSideRelationProperty : MappingReflectionTestBase
   {
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
     private Type _classType;
 
     public override void SetUp ()
@@ -37,7 +37,7 @@ public override void SetUp ()
       base.SetUp();
 
       _classType = typeof(ClassWithVirtualRelationEndPoints);
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: _classType);
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: _classType);
     }
 
     [Test]
@@ -128,7 +128,7 @@ public void GetMetadata_BidirectionalOneToOne ()
 
       Assert.IsInstanceOf(typeof(VirtualObjectRelationEndPointDefinition), actual);
       VirtualObjectRelationEndPointDefinition relationEndPointDefinition = (VirtualObjectRelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(
           relationEndPointDefinition.PropertyName,
           Is.EqualTo("Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.ReflectionBasedMappingSample.ClassWithVirtualRelationEndPoints.BidirectionalOneToOne"));
@@ -146,14 +146,14 @@ public void GetMetadata_BidirectionalOneToManyForDomainObjectCollection ()
 
       DomainModelConstraintProviderStub.Setup(stub => stub.IsNullable(propertyInfo)).Returns(true);
       SortExpressionDefinitionProviderStub
-          .Setup(stub => stub.GetSortExpression(It.IsAny<IPropertyInformation>(), It.IsAny<ClassDefinition>(), It.IsAny<string>()))
+          .Setup(stub => stub.GetSortExpression(It.IsAny<IPropertyInformation>(), It.IsAny<TypeDefinition>(), It.IsAny<string>()))
           .Throws(new InvalidOperationException("GetSortExpression() should not be called during GetMetadata()"));
 
       IRelationEndPointDefinition actual = relationEndPointReflector.GetMetadata();
 
       Assert.IsInstanceOf(typeof(DomainObjectCollectionRelationEndPointDefinition), actual);
       DomainObjectCollectionRelationEndPointDefinition relationEndPointDefinition = (DomainObjectCollectionRelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(
           relationEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -162,19 +162,19 @@ public void GetMetadata_BidirectionalOneToManyForDomainObjectCollection ()
       Assert.That(relationEndPointDefinition.Cardinality, Is.EqualTo(CardinalityType.Many));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
 
-      var oppositeClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
+      var oppositeTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
       var oppositeEndPointDefinition = new Mock<IRelationEndPointDefinition>();
-      oppositeEndPointDefinition.Setup(stub => stub.ClassDefinition).Returns(oppositeClassDefinition);
+      oppositeEndPointDefinition.Setup(stub => stub.TypeDefinition).Returns(oppositeTypeDefinition);
       var relationDefinition = new RelationDefinition("relation", relationEndPointDefinition, oppositeEndPointDefinition.Object);
       relationEndPointDefinition.SetRelationDefinition(relationDefinition);
       var oppositePropertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(
-          oppositeClassDefinition,
-          oppositeClassDefinition.ClassType,
+          oppositeTypeDefinition,
+          oppositeTypeDefinition.Type,
           "NoAttributeForDomainObjectCollection");
       var sortExpressionDefinition = new SortExpressionDefinition(new[] { SortExpressionDefinitionObjectMother.CreateSortedPropertyAscending(oppositePropertyDefinition) });
       SortExpressionDefinitionProviderStub.Reset();
       SortExpressionDefinitionProviderStub
-          .Setup(stub => stub.GetSortExpression(relationEndPointDefinition.PropertyInfo, oppositeClassDefinition, "NoAttributeForDomainObjectCollection"))
+          .Setup(stub => stub.GetSortExpression(relationEndPointDefinition.PropertyInfo, oppositeTypeDefinition, "NoAttributeForDomainObjectCollection"))
           .Returns(sortExpressionDefinition);
 
       Assert.That(relationEndPointDefinition.GetSortExpression(), Is.SameAs(sortExpressionDefinition));
@@ -188,14 +188,14 @@ public void GetMetadata_BidirectionalOneToManyForVirtualCollection ()
 
       DomainModelConstraintProviderStub.Setup(stub => stub.IsNullable(propertyInfo)).Returns(true);
       SortExpressionDefinitionProviderStub
-          .Setup(stub => stub.GetSortExpression(It.IsAny<IPropertyInformation>(), It.IsAny<ClassDefinition>(), It.IsAny<string>()))
+          .Setup(stub => stub.GetSortExpression(It.IsAny<IPropertyInformation>(), It.IsAny<TypeDefinition>(), It.IsAny<string>()))
           .Throws(new InvalidOperationException("GetSortExpression() should not be called during GetMetadata()"));
 
       IRelationEndPointDefinition actual = relationEndPointReflector.GetMetadata();
 
       Assert.IsInstanceOf(typeof(VirtualCollectionRelationEndPointDefinition), actual);
       VirtualCollectionRelationEndPointDefinition relationEndPointDefinition = (VirtualCollectionRelationEndPointDefinition)actual;
-      Assert.That(relationEndPointDefinition.ClassDefinition, Is.SameAs(_classDefinition));
+      Assert.That(relationEndPointDefinition.TypeDefinition, Is.SameAs(_typeDefinition));
       Assert.That(
           relationEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -204,19 +204,19 @@ public void GetMetadata_BidirectionalOneToManyForVirtualCollection ()
       Assert.That(relationEndPointDefinition.Cardinality, Is.EqualTo(CardinalityType.Many));
       Assert.That(relationEndPointDefinition.HasRelationDefinitionBeenSet, Is.False);
 
-      var oppositeClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
+      var oppositeTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithRealRelationEndPoints));
       var oppositeEndPointDefinition = new Mock<IRelationEndPointDefinition>();
-      oppositeEndPointDefinition.Setup(stub => stub.ClassDefinition).Returns(oppositeClassDefinition);
+      oppositeEndPointDefinition.Setup(stub => stub.TypeDefinition).Returns(oppositeTypeDefinition);
       var relationDefinition = new RelationDefinition("relation", relationEndPointDefinition, oppositeEndPointDefinition.Object);
       relationEndPointDefinition.SetRelationDefinition(relationDefinition);
       var oppositePropertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(
-          oppositeClassDefinition,
-          oppositeClassDefinition.ClassType,
+          oppositeTypeDefinition,
+          oppositeTypeDefinition.Type,
           "NoAttributeForVirtualCollection");
       var sortExpressionDefinition = new SortExpressionDefinition(new[] { SortExpressionDefinitionObjectMother.CreateSortedPropertyAscending(oppositePropertyDefinition) });
       SortExpressionDefinitionProviderStub.Reset();
       SortExpressionDefinitionProviderStub
-          .Setup(stub => stub.GetSortExpression(relationEndPointDefinition.PropertyInfo, oppositeClassDefinition, "NoAttributeForVirtualCollection"))
+          .Setup(stub => stub.GetSortExpression(relationEndPointDefinition.PropertyInfo, oppositeTypeDefinition, "NoAttributeForVirtualCollection"))
           .Returns(sortExpressionDefinition);
 
       Assert.That(relationEndPointDefinition.GetSortExpression(), Is.SameAs(sortExpressionDefinition));
@@ -252,7 +252,7 @@ public void IsVirtualEndRelationEndpoint_BidirectionalOneToManyForVirtualCollect
     private RdbmsRelationEndPointReflector CreateRelationEndPointReflector (PropertyInfoAdapter propertyInfo)
     {
       return new RdbmsRelationEndPointReflector(
-          _classDefinition,
+          _typeDefinition,
           propertyInfo,
           Configuration.NameResolver,
           PropertyMetadataProvider,
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationReflectorTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationReflectorTest.cs
index c9a2f08056..3ade9fe1b8 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationReflectorTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationReflectorTest.cs
@@ -35,35 +35,35 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   [TestFixture]
   public class RelationReflectorTest : MappingReflectionTestBase
   {
-    private ClassDefinition _classWithRealRelationEndPoints;
-    private ClassDefinition _classWithVirtualRelationEndPoints;
-    private ClassDefinition _classWithBothEndPointsOnSameClassClassDefinition;
-    private Dictionary<Type, ClassDefinition> _classDefinitions;
+    private TypeDefinition _classWithRealRelationEndPoints;
+    private TypeDefinition _classWithVirtualRelationEndPoints;
+    private TypeDefinition _classWithBothEndPointsOnSameClassTypeDefinition;
+    private Dictionary<Type, TypeDefinition> _classDefinitions;
     private ReflectionBasedMemberInformationNameResolver _memberInformationNameResolver;
 
     public override void SetUp ()
     {
       base.SetUp();
       _memberInformationNameResolver = new ReflectionBasedMemberInformationNameResolver();
-      _classWithRealRelationEndPoints = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithRealRelationEndPoints));
+      _classWithRealRelationEndPoints = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithRealRelationEndPoints));
       _classWithRealRelationEndPoints.SetPropertyDefinitions(new PropertyDefinitionCollection());
       _classWithRealRelationEndPoints.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
 
-      _classWithVirtualRelationEndPoints = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithVirtualRelationEndPoints));
+      _classWithVirtualRelationEndPoints = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithVirtualRelationEndPoints));
       _classWithVirtualRelationEndPoints.SetPropertyDefinitions(new PropertyDefinitionCollection());
       _classWithVirtualRelationEndPoints.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
 
-      _classWithBothEndPointsOnSameClassClassDefinition =
-          ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithBothEndPointsOnSameClass));
-      _classWithBothEndPointsOnSameClassClassDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
-      _classWithBothEndPointsOnSameClassClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+      _classWithBothEndPointsOnSameClassTypeDefinition =
+          TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithBothEndPointsOnSameClass));
+      _classWithBothEndPointsOnSameClassTypeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
+      _classWithBothEndPointsOnSameClassTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
 
       _classDefinitions = new[]
                           {
                               _classWithRealRelationEndPoints,
                               _classWithVirtualRelationEndPoints,
-                              _classWithBothEndPointsOnSameClassClassDefinition
-                          }.ToDictionary(cd => cd.ClassType);
+                              _classWithBothEndPointsOnSameClassTypeDefinition
+                          }.ToDictionary(cd => cd.Type);
     }
 
     [Test]
@@ -97,7 +97,7 @@ public void GetMetadata_Unidirectional_EndPoint0 ()
       var endPointDefinition = (RelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[0];
 
       Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_classWithRealRelationEndPoints.MyPropertyDefinitions[0]));
-      Assert.That(endPointDefinition.ClassDefinition, Is.SameAs(_classWithRealRelationEndPoints));
+      Assert.That(endPointDefinition.TypeDefinition, Is.SameAs(_classWithRealRelationEndPoints));
     }
 
     [Test]
@@ -111,7 +111,7 @@ public void GetMetadata_Unidirectional_EndPoint1 ()
       RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[1], Is.InstanceOf(typeof(AnonymousRelationEndPointDefinition)));
       var oppositeEndPointDefinition = (AnonymousRelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[1];
-      Assert.That(oppositeEndPointDefinition.ClassDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
+      Assert.That(oppositeEndPointDefinition.TypeDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
     }
 
     [Test]
@@ -133,7 +133,7 @@ public void GetMetadata_WithRealRelationEndPoint_BidirectionalOneToOne_CheckEndP
       var endPointDefinition = (RelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[0];
 
       Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_classWithRealRelationEndPoints.MyPropertyDefinitions[0]));
-      Assert.That(endPointDefinition.ClassDefinition, Is.SameAs(_classWithRealRelationEndPoints));
+      Assert.That(endPointDefinition.TypeDefinition, Is.SameAs(_classWithRealRelationEndPoints));
     }
 
     [Test]
@@ -153,7 +153,7 @@ public void GetMetadata_WithRealRelationEndPoint_BidirectionalOneToOne_CheckEndP
       Assert.That(actualRelationDefinition.EndPointDefinitions[1], Is.InstanceOf(typeof(VirtualObjectRelationEndPointDefinition)));
       var oppositeEndPointDefinition =
           (VirtualObjectRelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[1];
-      Assert.That(oppositeEndPointDefinition.ClassDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
+      Assert.That(oppositeEndPointDefinition.TypeDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
       Assert.That(
           oppositeEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -175,7 +175,7 @@ public void GetMetadata_WithVirtualRelationEndPoint_BidirectionalOneToOne_CheckE
       Assert.That(actualRelationDefinition.EndPointDefinitions[0], Is.InstanceOf(typeof(VirtualObjectRelationEndPointDefinition)));
       var oppositeEndPointDefinition =
           (VirtualObjectRelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[0];
-      Assert.That(oppositeEndPointDefinition.ClassDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
+      Assert.That(oppositeEndPointDefinition.TypeDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
       Assert.That(
           oppositeEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -199,7 +199,7 @@ public void GetMetadata_WithVirtualRelationEndPoint_BidirectionalOneToOne_CheckE
       var endPointDefinition = (RelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[1];
 
       Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_classWithRealRelationEndPoints.MyPropertyDefinitions[0]));
-      Assert.That(endPointDefinition.ClassDefinition, Is.SameAs(_classWithRealRelationEndPoints));
+      Assert.That(endPointDefinition.TypeDefinition, Is.SameAs(_classWithRealRelationEndPoints));
     }
 
     [Test]
@@ -221,7 +221,7 @@ public void GetMetadata_WithRealRelationEndPoint_BidirectionalOneToManyForDomain
       var endPointDefinition = (RelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[0];
 
       Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_classWithRealRelationEndPoints.MyPropertyDefinitions[0]));
-      Assert.That(endPointDefinition.ClassDefinition, Is.SameAs(_classWithRealRelationEndPoints));
+      Assert.That(endPointDefinition.TypeDefinition, Is.SameAs(_classWithRealRelationEndPoints));
     }
 
     [Test]
@@ -243,7 +243,7 @@ public void GetMetadata_WithRealRelationEndPoint_BidirectionalOneToManyForVirtua
       var endPointDefinition = (RelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[0];
 
       Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_classWithRealRelationEndPoints.MyPropertyDefinitions[0]));
-      Assert.That(endPointDefinition.ClassDefinition, Is.SameAs(_classWithRealRelationEndPoints));
+      Assert.That(endPointDefinition.TypeDefinition, Is.SameAs(_classWithRealRelationEndPoints));
     }
 
     [Test]
@@ -262,7 +262,7 @@ public void GetMetadata_WithRealRelationEndPoint_BidirectionalOneToManyForDomain
       RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[1], Is.InstanceOf(typeof(DomainObjectCollectionRelationEndPointDefinition)));
       var oppositeEndPointDefinition = (DomainObjectCollectionRelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[1];
-      Assert.That(oppositeEndPointDefinition.ClassDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
+      Assert.That(oppositeEndPointDefinition.TypeDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
       Assert.That(
           oppositeEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -286,7 +286,7 @@ public void GetMetadata_WithRealRelationEndPoint_BidirectionalOneToManyForVirtua
       RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[1], Is.InstanceOf(typeof(VirtualCollectionRelationEndPointDefinition)));
       var oppositeEndPointDefinition = (VirtualCollectionRelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[1];
-      Assert.That(oppositeEndPointDefinition.ClassDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
+      Assert.That(oppositeEndPointDefinition.TypeDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
       Assert.That(
           oppositeEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -297,24 +297,24 @@ public void GetMetadata_WithRealRelationEndPoint_BidirectionalOneToManyForVirtua
     [Test]
     public void GetMetadata_WithRealRelationEndPoint_OpenGenericProperty ()
     {
-        var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType : typeof(ClosedGenericClassWithRealRelationEndPoints));
-        classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
-        classDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+        var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType : typeof(ClosedGenericClassWithRealRelationEndPoints));
+        typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
+        typeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
         EnsurePropertyDefinitionExisitsOnClassDefinition(
-                classDefinition,
+                typeDefinition,
                 typeof(ClosedGenericClassWithRealRelationEndPoints),
                 "BaseBidirectionalOneToOne");
 
-        var otherClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType : typeof(GenericClassWithRealRelationEndPointsNotInMapping<>));
-        otherClassDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
-        otherClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+        var otherTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType : typeof(GenericClassWithRealRelationEndPointsNotInMapping<>));
+        otherTypeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
+        otherTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
         EnsurePropertyDefinitionExisitsOnClassDefinition(
-                otherClassDefinition,
+                otherTypeDefinition,
                 typeof(GenericClassWithRealRelationEndPointsNotInMapping<>),
                 "BaseBidirectionalOneToOne");
 
         var relationReflector = CreateRelationReflector(
-                otherClassDefinition,
+                otherTypeDefinition,
                 typeof(GenericClassWithRealRelationEndPointsNotInMapping<>),
                 "BaseBidirectionalOneToOne");
 
@@ -336,7 +336,7 @@ public void GetMetadata_WithVirtualRelationEndPoint_BidirectionalOneToManyForDom
       RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[0], Is.InstanceOf(typeof(DomainObjectCollectionRelationEndPointDefinition)));
       var oppositeEndPointDefinition = (DomainObjectCollectionRelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[0];
-      Assert.That(oppositeEndPointDefinition.ClassDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
+      Assert.That(oppositeEndPointDefinition.TypeDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
       Assert.That(
           oppositeEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -357,7 +357,7 @@ public void GetMetadata_WithVirtualRelationEndPoint_BidirectionalOneToManyForVir
       RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[0], Is.InstanceOf(typeof(VirtualCollectionRelationEndPointDefinition)));
       var oppositeEndPointDefinition = (VirtualCollectionRelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[0];
-      Assert.That(oppositeEndPointDefinition.ClassDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
+      Assert.That(oppositeEndPointDefinition.TypeDefinition, Is.SameAs(_classWithVirtualRelationEndPoints));
       Assert.That(
           oppositeEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -381,7 +381,7 @@ public void GetMetadata_WithVirtualRelationEndPoint_BidirectionalOneToManyForDom
       var endPointDefinition = (RelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[1];
 
       Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_classWithRealRelationEndPoints.MyPropertyDefinitions[0]));
-      Assert.That(endPointDefinition.ClassDefinition, Is.SameAs(_classWithRealRelationEndPoints));
+      Assert.That(endPointDefinition.TypeDefinition, Is.SameAs(_classWithRealRelationEndPoints));
     }
 
     [Test]
@@ -400,18 +400,18 @@ public void GetMetadata_WithVirtualRelationEndPoint_BidirectionalOneToManyForVir
       var endPointDefinition = (RelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[1];
 
       Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_classWithRealRelationEndPoints.MyPropertyDefinitions[0]));
-      Assert.That(endPointDefinition.ClassDefinition, Is.SameAs(_classWithRealRelationEndPoints));
+      Assert.That(endPointDefinition.TypeDefinition, Is.SameAs(_classWithRealRelationEndPoints));
     }
 
     [Test]
     public void GetMetadata_BidirectionalOneToMany_WithBothEndPointsOnSameClass_EndPoint0 ()
     {
       EnsurePropertyDefinitionExisitsOnClassDefinition(
-          _classWithBothEndPointsOnSameClassClassDefinition, typeof(ClassWithBothEndPointsOnSameClass), "Parent");
+          _classWithBothEndPointsOnSameClassTypeDefinition, typeof(ClassWithBothEndPointsOnSameClass), "Parent");
       EnsurePropertyDefinitionExisitsOnClassDefinition(
-          _classWithBothEndPointsOnSameClassClassDefinition, typeof(ClassWithBothEndPointsOnSameClass), "Children");
+          _classWithBothEndPointsOnSameClassTypeDefinition, typeof(ClassWithBothEndPointsOnSameClass), "Children");
       var relationReflector = CreateRelationReflector(
-          _classWithBothEndPointsOnSameClassClassDefinition,
+          _classWithBothEndPointsOnSameClassTypeDefinition,
           typeof(ClassWithBothEndPointsOnSameClass),
           "Parent");
 
@@ -420,26 +420,26 @@ public void GetMetadata_BidirectionalOneToMany_WithBothEndPointsOnSameClass_EndP
 
       var endPointDefinition = (RelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[0];
 
-      Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_classWithBothEndPointsOnSameClassClassDefinition.MyPropertyDefinitions[0]));
-      Assert.That(endPointDefinition.ClassDefinition, Is.SameAs(_classWithBothEndPointsOnSameClassClassDefinition));
+      Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_classWithBothEndPointsOnSameClassTypeDefinition.MyPropertyDefinitions[0]));
+      Assert.That(endPointDefinition.TypeDefinition, Is.SameAs(_classWithBothEndPointsOnSameClassTypeDefinition));
     }
 
     [Test]
     public void GetMetadata_BidirectionalOneToMany_WithBothEndPointsOnSameClass_EndPoint1 ()
     {
       EnsurePropertyDefinitionExisitsOnClassDefinition(
-          _classWithBothEndPointsOnSameClassClassDefinition, typeof(ClassWithBothEndPointsOnSameClass), "Parent");
+          _classWithBothEndPointsOnSameClassTypeDefinition, typeof(ClassWithBothEndPointsOnSameClass), "Parent");
       EnsurePropertyDefinitionExisitsOnClassDefinition(
-          _classWithBothEndPointsOnSameClassClassDefinition, typeof(ClassWithBothEndPointsOnSameClass), "Children");
+          _classWithBothEndPointsOnSameClassTypeDefinition, typeof(ClassWithBothEndPointsOnSameClass), "Children");
       var relationReflector = CreateRelationReflector(
-          _classWithBothEndPointsOnSameClassClassDefinition,
+          _classWithBothEndPointsOnSameClassTypeDefinition,
           typeof(ClassWithBothEndPointsOnSameClass),
           "Parent");
 
       RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[1], Is.InstanceOf(typeof(DomainObjectCollectionRelationEndPointDefinition)));
       var oppositeEndPointDefinition = (DomainObjectCollectionRelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[1];
-      Assert.That(oppositeEndPointDefinition.ClassDefinition, Is.SameAs(_classWithBothEndPointsOnSameClassClassDefinition));
+      Assert.That(oppositeEndPointDefinition.TypeDefinition, Is.SameAs(_classWithBothEndPointsOnSameClassTypeDefinition));
       Assert.That(
           oppositeEndPointDefinition.PropertyName,
           Is.EqualTo(
@@ -453,19 +453,19 @@ public void GetMetadata_WithInvalidOppositePropertyName ()
       var type1 = GetClassWithInvalidBidirectionalRelationLeftSide();
       var type2 = GetClassWithInvalidBidirectionalRelationRightSide();
 
-      var classDefinition1 = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(type1);
-      classDefinition1.SetPropertyDefinitions(new PropertyDefinitionCollection());
-      classDefinition1.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
-      var propertyInfo = EnsurePropertyDefinitionExisitsOnClassDefinition(classDefinition1, type1, "InvalidOppositePropertyNameLeftSide");
-      var classDefinition2 = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(type2);
-      classDefinition2.SetPropertyDefinitions(new PropertyDefinitionCollection());
-      classDefinition2.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+      var typeDefinition1 = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(type1);
+      typeDefinition1.SetPropertyDefinitions(new PropertyDefinitionCollection());
+      typeDefinition1.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+      var propertyInfo = EnsurePropertyDefinitionExisitsOnClassDefinition(typeDefinition1, type1, "InvalidOppositePropertyNameLeftSide");
+      var typeDefinition2 = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(type2);
+      typeDefinition2.SetPropertyDefinitions(new PropertyDefinitionCollection());
+      typeDefinition2.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
       EnsurePropertyDefinitionExisitsOnClassDefinition(
-          classDefinition2, type2, "InvalidPropertyNameInBidirectionalRelationAttributeOnOppositePropertyRightSide");
+          typeDefinition2, type2, "InvalidPropertyNameInBidirectionalRelationAttributeOnOppositePropertyRightSide");
 
-      var relationReflector = CreateRelationReflector(classDefinition1, propertyInfo);
-      _classDefinitions.Add(classDefinition1.ClassType, classDefinition1);
-      _classDefinitions.Add(classDefinition2.ClassType, classDefinition2);
+      var relationReflector = CreateRelationReflector(typeDefinition1, propertyInfo);
+      _classDefinitions.Add(typeDefinition1.Type, typeDefinition1);
+      _classDefinitions.Add(typeDefinition2.Type, typeDefinition2);
 
       var result = relationReflector.GetMetadata(_classDefinitions);
 
@@ -481,7 +481,7 @@ public void GetMetadata_WithInvalidOppositePropertyName ()
     [Test]
     public void GetMetadata_OppositeClassDefinition_IsDeclaringTypeOfOppositeProperty_NotReturnTypeOfThisProperty ()
     {
-      var originatingClass = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(Class1));
+      var originatingClass = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(Class1));
       originatingClass.SetPropertyDefinitions(new PropertyDefinitionCollection());
       originatingClass.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
       var originatingProperty =
@@ -492,30 +492,30 @@ public void GetMetadata_OppositeClassDefinition_IsDeclaringTypeOfOppositePropert
       classDeclaringOppositeProperty.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
       var oppositeProperty =
           EnsurePropertyDefinitionExisitsOnClassDefinition(classDeclaringOppositeProperty, typeof(BaseClass2), "RelationPropertyOnBaseClass");
-      var derivedOfClassDeclaringOppositeProperty = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedClass2), baseClass: classDeclaringOppositeProperty);
+      var derivedOfClassDeclaringOppositeProperty = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedClass2), baseClass: classDeclaringOppositeProperty);
       derivedOfClassDeclaringOppositeProperty.SetPropertyDefinitions(new PropertyDefinitionCollection());
       derivedOfClassDeclaringOppositeProperty.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
 
       // This tests the scenario that the relation property's return type is a subclass of the opposite property's declaring type
-      Assert.That(originatingProperty.PropertyType, Is.Not.SameAs(classDeclaringOppositeProperty.ClassType));
-      Assert.That(originatingProperty.PropertyType.BaseType, Is.SameAs(classDeclaringOppositeProperty.ClassType));
+      Assert.That(originatingProperty.PropertyType, Is.Not.SameAs(classDeclaringOppositeProperty.Type));
+      Assert.That(originatingProperty.PropertyType.BaseType, Is.SameAs(classDeclaringOppositeProperty.Type));
 
-      var classDefinitions = new[] { originatingClass, classDeclaringOppositeProperty, derivedOfClassDeclaringOppositeProperty }
-          .ToDictionary(cd => cd.ClassType);
+      var classDefinitions = new TypeDefinition[] { originatingClass, classDeclaringOppositeProperty, derivedOfClassDeclaringOppositeProperty }
+          .ToDictionary(cd => cd.Type);
 
       var relationReflector = CreateRelationReflector(originatingClass, originatingProperty);
       var result = relationReflector.GetMetadata(classDefinitions);
 
       Assert.That(result.EndPointDefinitions[0].PropertyInfo, Is.SameAs(originatingProperty));
-      Assert.That(result.EndPointDefinitions[0].ClassDefinition, Is.SameAs(originatingClass));
+      Assert.That(result.EndPointDefinitions[0].TypeDefinition, Is.SameAs(originatingClass));
       Assert.That(result.EndPointDefinitions[1].PropertyInfo, Is.SameAs(oppositeProperty));
-      Assert.That(result.EndPointDefinitions[1].ClassDefinition, Is.SameAs(classDeclaringOppositeProperty));
+      Assert.That(result.EndPointDefinitions[1].TypeDefinition, Is.SameAs(classDeclaringOppositeProperty));
     }
 
     [Test]
     public void GetMetadata_OppositeClassDefinition_IsInheritanceRoot_IfDeclaringTypeOfPropertyIsNotInMapping ()
     {
-      var originatingClass = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(
+      var originatingClass = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(
           typeof(TestDomain.RelationReflector.RelatedTypeDoesNotMatchOppositeProperty_AboveInheritanceRoot.Class1));
       originatingClass.SetPropertyDefinitions(new PropertyDefinitionCollection());
       originatingClass.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
@@ -524,44 +524,44 @@ public void GetMetadata_OppositeClassDefinition_IsInheritanceRoot_IfDeclaringTyp
           typeof(TestDomain.RelationReflector.RelatedTypeDoesNotMatchOppositeProperty_AboveInheritanceRoot.Class1),
           "RelationProperty");
 
-      var classNotInMapping = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassAboveInheritanceRoot));
+      var classNotInMapping = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassAboveInheritanceRoot));
       classNotInMapping.SetPropertyDefinitions(new PropertyDefinitionCollection());
       classNotInMapping.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
-      var derivedOfClassDeclaringOppositeProperty = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(Class2));
+      var derivedOfClassDeclaringOppositeProperty = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(Class2));
       derivedOfClassDeclaringOppositeProperty.SetPropertyDefinitions(new PropertyDefinitionCollection());
       derivedOfClassDeclaringOppositeProperty.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
       EnsurePropertyDefinitionExisitsOnClassDefinition(
           derivedOfClassDeclaringOppositeProperty, typeof(Class2), "RelationPropertyOnClassAboveInheritanceRoot");
 
-      Assert.That(originatingProperty.PropertyType, Is.Not.SameAs(classNotInMapping.ClassType));
-      Assert.That(originatingProperty.PropertyType.BaseType, Is.SameAs(classNotInMapping.ClassType));
+      Assert.That(originatingProperty.PropertyType, Is.Not.SameAs(classNotInMapping.Type));
+      Assert.That(originatingProperty.PropertyType.BaseType, Is.SameAs(classNotInMapping.Type));
 
-      var classDefinitions = new[] { originatingClass, derivedOfClassDeclaringOppositeProperty }.ToDictionary(cd => cd.ClassType);
+      var classDefinitions = new TypeDefinition[] { originatingClass, derivedOfClassDeclaringOppositeProperty }.ToDictionary(cd => cd.Type);
 
       var relationReflector = CreateRelationReflector(originatingClass, originatingProperty);
       var result = relationReflector.GetMetadata(classDefinitions);
 
       Assert.That(result.EndPointDefinitions[0].PropertyInfo, Is.SameAs(originatingProperty));
-      Assert.That(result.EndPointDefinitions[0].ClassDefinition, Is.SameAs(originatingClass));
+      Assert.That(result.EndPointDefinitions[0].TypeDefinition, Is.SameAs(originatingClass));
       Assert.That(result.EndPointDefinitions[1].PropertyInfo.Name, Is.EqualTo("RelationPropertyOnClassAboveInheritanceRoot"));
-      Assert.That(result.EndPointDefinitions[1].ClassDefinition, Is.SameAs(derivedOfClassDeclaringOppositeProperty));
+      Assert.That(result.EndPointDefinitions[1].TypeDefinition, Is.SameAs(derivedOfClassDeclaringOppositeProperty));
     }
 
     [Test]
     public void GetMetadata_RelatedPropertyTypeIsNotInMapping ()
     {
       var originatingClass =
-          ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(TestDomain.RelationReflector.RelatedPropertyTypeIsNotInMapping.Class1));
+          TypeDefinitionObjectMother.CreateClassDefinitionWithMixinsAndDefaultProperties(typeof(TestDomain.RelationReflector.RelatedPropertyTypeIsNotInMapping.Class1));
       originatingClass.SetPropertyDefinitions(new PropertyDefinitionCollection());
       originatingClass.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
       var originatingProperty = EnsurePropertyDefinitionExisitsOnClassDefinition(
           originatingClass, typeof(TestDomain.RelationReflector.RelatedPropertyTypeIsNotInMapping.Class1), "BidirectionalRelationProperty");
-      var classDefinitions = new[] { originatingClass }.ToDictionary(cd => cd.ClassType);
+      var classDefinitions = new TypeDefinition[] { originatingClass }.ToDictionary(cd => cd.Type);
 
       var relationReflector = CreateRelationReflector(originatingClass, originatingProperty);
       var result = relationReflector.GetMetadata(classDefinitions);
 
-      Assert.That(result.EndPointDefinitions[0].ClassDefinition, Is.EqualTo(originatingClass));
+      Assert.That(result.EndPointDefinitions[0].TypeDefinition, Is.EqualTo(originatingClass));
       Assert.That(result.EndPointDefinitions[1], Is.TypeOf(typeof(PropertyNotFoundRelationEndPointDefinition)));
       Assert.That(result.EndPointDefinitions[1].PropertyName, Is.EqualTo("RelationProperty"));
     }
@@ -569,40 +569,40 @@ public void GetMetadata_RelatedPropertyTypeIsNotInMapping ()
     [Test]
     public void GetMetadata_OppositePropertyIsAlsoDeclaredInBaseClass ()
     {
-      var originatingClass = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithOppositeProperty));
+      var originatingClass = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithOppositeProperty));
       originatingClass.SetPropertyDefinitions(new PropertyDefinitionCollection());
       originatingClass.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
       var originatingProperty =
           EnsurePropertyDefinitionExisitsOnClassDefinition(originatingClass, typeof(ClassWithOppositeProperty), "OppositeProperty");
 
-      var oppositeBaseClass = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(OppositeBaseClass));
+      var oppositeBaseClass = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(OppositeBaseClass));
       oppositeBaseClass.SetPropertyDefinitions(new PropertyDefinitionCollection());
       oppositeBaseClass.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
       var oppositePropertyFromBaseClass =
           EnsurePropertyDefinitionExisitsOnClassDefinition(oppositeBaseClass, typeof(OppositeBaseClass), "OppositeProperty");
 
-      var oppositeClass = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(OppositeClass));
+      var oppositeClass = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(OppositeClass));
       oppositeClass.SetPropertyDefinitions(new PropertyDefinitionCollection());
       oppositeClass.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
       var oppositeProperty =
           EnsurePropertyDefinitionExisitsOnClassDefinition(oppositeClass, typeof(OppositeClass), "OppositeProperty");
 
-      var classDefinitions = new[] { originatingClass, oppositeClass, oppositeBaseClass }.ToDictionary(cd => cd.ClassType);
+      var classDefinitions = new TypeDefinition[] { originatingClass, oppositeClass, oppositeBaseClass }.ToDictionary(cd => cd.Type);
       var relationReflector = CreateRelationReflector(originatingClass, originatingProperty);
       var result = relationReflector.GetMetadata(classDefinitions);
 
       Assert.That(result.EndPointDefinitions[0].PropertyInfo, Is.SameAs(originatingProperty));
-      Assert.That(result.EndPointDefinitions[0].ClassDefinition, Is.SameAs(originatingClass));
+      Assert.That(result.EndPointDefinitions[0].TypeDefinition, Is.SameAs(originatingClass));
       Assert.That(result.EndPointDefinitions[1].PropertyInfo, Is.Not.SameAs(oppositePropertyFromBaseClass));
       Assert.That(result.EndPointDefinitions[1].PropertyInfo, Is.SameAs(oppositeProperty));
-      Assert.That(result.EndPointDefinitions[1].ClassDefinition, Is.SameAs(oppositeClass));
+      Assert.That(result.EndPointDefinitions[1].TypeDefinition, Is.SameAs(oppositeClass));
     }
 
     [Test]
     public void GetOppositePropertyInfo_WithStorageClassNoneOppositeProperty ()
     {
       var classType = typeof(TestDomain.RelationReflector.OppositePropertyHasStorageClassNoneAttribute.ClassWithOppositeProperty);
-      var originatingClass = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(classType);
+      var originatingClass = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(classType);
       var originatingProperty = PropertyInfoAdapter.Create(classType.GetProperty("OppositeProperty"));
 
       var relationReflector = CreateRelationReflector(originatingClass, originatingProperty);
@@ -621,26 +621,26 @@ private Type GetClassWithInvalidBidirectionalRelationRightSide ()
       return typeof(ClassWithInvalidBidirectionalRelationRightSide);
     }
 
-    private RelationReflector CreateRelationReflector (ClassDefinition classDefinition, IPropertyInformation propertyInfo)
+    private RelationReflector CreateRelationReflector (TypeDefinition typeDefinition, IPropertyInformation propertyInfo)
     {
-      return new RelationReflector(classDefinition, propertyInfo, _memberInformationNameResolver, PropertyMetadataProvider);
+      return new RelationReflector(typeDefinition, propertyInfo, _memberInformationNameResolver, PropertyMetadataProvider);
     }
 
-    private RelationReflector CreateRelationReflector (ClassDefinition classDefinition, Type declaringType, string propertyName)
+    private RelationReflector CreateRelationReflector (TypeDefinition typeDefinition, Type declaringType, string propertyName)
     {
-      var propertyInfo = EnsurePropertyDefinitionExisitsOnClassDefinition(classDefinition, declaringType, propertyName);
-      return CreateRelationReflector(classDefinition, propertyInfo);
+      var propertyInfo = EnsurePropertyDefinitionExisitsOnClassDefinition(typeDefinition, declaringType, propertyName);
+      return CreateRelationReflector(typeDefinition, propertyInfo);
     }
 
     private IPropertyInformation EnsurePropertyDefinitionExisitsOnClassDefinition (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         Type declaringType,
         string propertyName)
     {
       var propertyInfo =
           PropertyInfoAdapter.Create(declaringType.GetProperty(propertyName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance));
       var propertyReflector = new PropertyReflector(
-          classDefinition,
+          typeDefinition,
           propertyInfo,
           new ReflectionBasedMemberInformationNameResolver(),
           PropertyMetadataProvider,
@@ -648,14 +648,14 @@ private IPropertyInformation EnsurePropertyDefinitionExisitsOnClassDefinition (
           PropertyDefaultValueProviderStub.Object);
       var propertyDefinition = propertyReflector.GetMetadata();
 
-      if (!classDefinition.MyPropertyDefinitions.Contains(propertyDefinition.PropertyName))
+      if (!typeDefinition.MyPropertyDefinitions.Contains(propertyDefinition.PropertyName))
       {
-        var propertyDefinitions = new PropertyDefinitionCollection(classDefinition.MyPropertyDefinitions, false);
+        var propertyDefinitions = new PropertyDefinitionCollection(typeDefinition.MyPropertyDefinitions, false);
         propertyDefinitions.Add(propertyDefinition);
-        PrivateInvoke.SetNonPublicField(classDefinition, "_propertyDefinitions", propertyDefinitions);
-        var endPoints = new RelationEndPointDefinitionCollection(classDefinition.MyRelationEndPointDefinitions, false);
-        endPoints.Add(MappingObjectFactory.CreateRelationEndPointDefinition(classDefinition, propertyInfo));
-        PrivateInvoke.SetNonPublicField(classDefinition, "_relationEndPoints", endPoints);
+        PrivateInvoke.SetNonPublicField(typeDefinition, "_propertyDefinitions", propertyDefinitions);
+        var endPoints = new RelationEndPointDefinitionCollection(typeDefinition.MyRelationEndPointDefinitions, false);
+        endPoints.Add(MappingObjectFactory.CreateRelationEndPointDefinition(typeDefinition, propertyInfo));
+        PrivateInvoke.SetNonPublicField(typeDefinition, "_relationEndPoints", endPoints);
       }
 
       return propertyInfo;
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationReflectorWithMixinsTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationReflectorWithMixinsTest.cs
index 1465907ba1..8521e998bf 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationReflectorWithMixinsTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/RelationReflectorWithMixinsTest.cs
@@ -30,45 +30,45 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   [TestFixture]
   public class RelationReflectorWithMixinsTest : MappingReflectionTestBase
   {
-    private ClassDefinition _mixinTargetClassDefinition;
-    private ClassDefinition _multiMixinTargetClassDefinition;
-    private ClassDefinition _multiMixinRelatedClassDefinition;
-    private ClassDefinition _relatedClassDefinition;
-    private ClassDefinition _inheritanceRootInheritingMixinClassDefinition;
-    private Dictionary<Type, ClassDefinition> _classDefinitions;
+    private TypeDefinition _mixinTargetTypeDefinition;
+    private TypeDefinition _multiMixinTargetTypeDefinition;
+    private TypeDefinition _multiMixinRelatedTypeDefinition;
+    private TypeDefinition _relatedTypeDefinition;
+    private TypeDefinition _inheritanceRootInheritingMixinTypeDefinition;
+    private Dictionary<Type, TypeDefinition> _typeDefinitions;
 
     public override void SetUp ()
     {
       base.SetUp();
 
-      _mixinTargetClassDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(
+      _mixinTargetTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(
           typeof(TargetClassForPersistentMixin),
           typeof(MixinAddingPersistentProperties));
-      _multiMixinTargetClassDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(
+      _multiMixinTargetTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(
           typeof(TargetClassReceivingTwoReferencesToDerivedClass),
           typeof(MixinAddingTwoReferencesToDerivedClass1),
           typeof(MixinAddingTwoReferencesToDerivedClass2));
-      _multiMixinRelatedClassDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedClassWithTwoBaseReferencesViaMixins));
-      _relatedClassDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(
+      _multiMixinRelatedTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedClassWithTwoBaseReferencesViaMixins));
+      _relatedTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(
           typeof(RelationTargetForPersistentMixin),
           typeof(MixinAddingPersistentProperties));
-      _inheritanceRootInheritingMixinClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(
+      _inheritanceRootInheritingMixinTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(
           classType: typeof(InheritanceRootInheritingPersistentMixin),
           persistentMixinFinder: new PersistentMixinFinder(typeof(InheritanceRootInheritingPersistentMixin), true));
 
-      _classDefinitions = new[] { _mixinTargetClassDefinition, _relatedClassDefinition, _multiMixinTargetClassDefinition }
-          .ToDictionary(cd => cd.ClassType);
+      _typeDefinitions = new[] { _mixinTargetTypeDefinition, _relatedTypeDefinition, _multiMixinTargetTypeDefinition }
+          .ToDictionary(cd => cd.Type);
     }
 
     [Test]
     public void GetMetadata_Mixed_RealSide_ID ()
     {
       var relationReflector = CreateRelationReflectorForProperty(
-          _mixinTargetClassDefinition,
+          _mixinTargetTypeDefinition,
           typeof(MixinAddingPersistentProperties),
           "UnidirectionalRelationProperty");
 
-      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
+      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_typeDefinitions);
       Assert.That(
           actualRelationDefinition.ID,
           Is.EqualTo(
@@ -79,13 +79,13 @@ public void GetMetadata_Mixed_RealSide_ID ()
     [Test]
     public void GetMetadata_Mixed_VirtualSide ()
     {
-      CreateRelationReflectorForProperty(_relatedClassDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty2");
+      CreateRelationReflectorForProperty(_relatedTypeDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty2");
       var relationReflector = CreateRelationReflectorForProperty(
-          _mixinTargetClassDefinition,
+          _mixinTargetTypeDefinition,
           typeof(MixinAddingPersistentProperties),
           "VirtualRelationProperty");
 
-      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
+      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_typeDefinitions);
       Assert.That(
           actualRelationDefinition.ID,
           Is.EqualTo(
@@ -98,66 +98,66 @@ public void GetMetadata_Mixed_VirtualSide ()
     public void GetMetadata_Mixed_Unidirectional_EndPointDefinition0 ()
     {
       var relationReflector = CreateRelationReflectorForProperty(
-          _mixinTargetClassDefinition,
+          _mixinTargetTypeDefinition,
           typeof(MixinAddingPersistentProperties),
           "UnidirectionalRelationProperty");
 
-      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
+      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_typeDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[0], Is.InstanceOf(typeof(RelationEndPointDefinition)));
 
       var endPointDefinition = (RelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[0];
 
-      Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_mixinTargetClassDefinition.MyPropertyDefinitions[0]));
-      Assert.That(endPointDefinition.ClassDefinition, Is.SameAs(_mixinTargetClassDefinition));
+      Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_mixinTargetTypeDefinition.MyPropertyDefinitions[0]));
+      Assert.That(endPointDefinition.TypeDefinition, Is.SameAs(_mixinTargetTypeDefinition));
     }
 
     [Test]
     public void GetMetadata_Mixed_Unidirectional_EndPointDefinition1 ()
     {
       var relationReflector = CreateRelationReflectorForProperty(
-          _mixinTargetClassDefinition,
+          _mixinTargetTypeDefinition,
           typeof(MixinAddingPersistentProperties),
           "UnidirectionalRelationProperty");
 
-      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
+      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_typeDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[1], Is.InstanceOf(typeof(AnonymousRelationEndPointDefinition)));
       var oppositeEndPointDefinition = (AnonymousRelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[1];
 
-      Assert.That(oppositeEndPointDefinition.ClassDefinition, Is.SameAs(_relatedClassDefinition));
+      Assert.That(oppositeEndPointDefinition.TypeDefinition, Is.SameAs(_relatedTypeDefinition));
     }
 
     [Test]
     public void GetMetadata_Mixed_BidirectionalOneToOne_EndPointDefinition0 ()
     {
-      CreateRelationReflectorForProperty(_relatedClassDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty1");
+      CreateRelationReflectorForProperty(_relatedTypeDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty1");
       var relationReflector = CreateRelationReflectorForProperty(
-          _mixinTargetClassDefinition,
+          _mixinTargetTypeDefinition,
           typeof(MixinAddingPersistentProperties),
           "RelationProperty");
 
-      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
+      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_typeDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[0], Is.InstanceOf(typeof(RelationEndPointDefinition)));
 
       var endPointDefinition = (RelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[0];
 
-      Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_mixinTargetClassDefinition.MyPropertyDefinitions[0]));
-      Assert.That(endPointDefinition.ClassDefinition, Is.SameAs(_mixinTargetClassDefinition));
+      Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_mixinTargetTypeDefinition.MyPropertyDefinitions[0]));
+      Assert.That(endPointDefinition.TypeDefinition, Is.SameAs(_mixinTargetTypeDefinition));
     }
 
     [Test]
     public void GetMetadata_Mixed_BidirectionalOneToOne_EndPointDefinition1 ()
     {
-      CreateRelationReflectorForProperty(_relatedClassDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty1");
+      CreateRelationReflectorForProperty(_relatedTypeDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty1");
       var relationReflector = CreateRelationReflectorForProperty(
-          _mixinTargetClassDefinition,
+          _mixinTargetTypeDefinition,
           typeof(MixinAddingPersistentProperties),
           "RelationProperty");
 
-      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
+      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_typeDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[1], Is.InstanceOf(typeof(VirtualObjectRelationEndPointDefinition)));
       var oppositeEndPointDefinition = (VirtualObjectRelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[1];
 
-      Assert.That(oppositeEndPointDefinition.ClassDefinition, Is.SameAs(_relatedClassDefinition));
+      Assert.That(oppositeEndPointDefinition.TypeDefinition, Is.SameAs(_relatedTypeDefinition));
       Assert.That(
           oppositeEndPointDefinition.PropertyName,
           Is.EqualTo("Remotion.Data.DomainObjects.UnitTests.MixedDomains.TestDomain.RelationTargetForPersistentMixin.RelationProperty1"));
@@ -167,34 +167,34 @@ public void GetMetadata_Mixed_BidirectionalOneToOne_EndPointDefinition1 ()
     [Test]
     public void GetMetadata_Mixed_BidirectionalOneToMany_EndPoint0 ()
     {
-      CreateRelationReflectorForProperty(_relatedClassDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty4");
+      CreateRelationReflectorForProperty(_relatedTypeDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty4");
       var relationReflector = CreateRelationReflectorForProperty(
-          _mixinTargetClassDefinition,
+          _mixinTargetTypeDefinition,
           typeof(MixinAddingPersistentProperties),
           "CollectionPropertyNSide");
 
-      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
+      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_typeDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[0], Is.InstanceOf(typeof(RelationEndPointDefinition)));
 
       var endPointDefinition = (RelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[0];
 
-      Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_mixinTargetClassDefinition.MyPropertyDefinitions[0]));
-      Assert.That(endPointDefinition.ClassDefinition, Is.SameAs(_mixinTargetClassDefinition));
+      Assert.That(endPointDefinition.PropertyDefinition, Is.EqualTo(_mixinTargetTypeDefinition.MyPropertyDefinitions[0]));
+      Assert.That(endPointDefinition.TypeDefinition, Is.SameAs(_mixinTargetTypeDefinition));
     }
 
     [Test]
     public void GetMetadata_Mixed_BidirectionalOneToMany_EndPoint1 ()
     {
-      CreateRelationReflectorForProperty(_relatedClassDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty4");
+      CreateRelationReflectorForProperty(_relatedTypeDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty4");
       var relationReflector = CreateRelationReflectorForProperty(
-          _mixinTargetClassDefinition,
+          _mixinTargetTypeDefinition,
           typeof(MixinAddingPersistentProperties),
           "CollectionPropertyNSide");
 
-      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_classDefinitions);
+      RelationDefinition actualRelationDefinition = relationReflector.GetMetadata(_typeDefinitions);
       Assert.That(actualRelationDefinition.EndPointDefinitions[1], Is.InstanceOf(typeof(DomainObjectCollectionRelationEndPointDefinition)));
       var oppositeEndPointDefinition = (DomainObjectCollectionRelationEndPointDefinition)actualRelationDefinition.EndPointDefinitions[1];
-      Assert.That(oppositeEndPointDefinition.ClassDefinition, Is.SameAs(_relatedClassDefinition));
+      Assert.That(oppositeEndPointDefinition.TypeDefinition, Is.SameAs(_relatedTypeDefinition));
       Assert.That(
           oppositeEndPointDefinition.PropertyName,
           Is.EqualTo("Remotion.Data.DomainObjects.UnitTests.MixedDomains.TestDomain.RelationTargetForPersistentMixin.RelationProperty4"));
@@ -204,56 +204,56 @@ public void GetMetadata_Mixed_BidirectionalOneToMany_EndPoint1 ()
     [Test]
     public void GetMetadata_Mixed_OppositePropertyPrivateOnBase ()
     {
-      CreateRelationReflectorForProperty(_relatedClassDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty5");
+      CreateRelationReflectorForProperty(_relatedTypeDefinition, typeof(RelationTargetForPersistentMixin), "RelationProperty5");
       var relationReflector = CreateRelationReflectorForProperty(
-          _mixinTargetClassDefinition,
+          _mixinTargetTypeDefinition,
           typeof(BaseForMixinAddingPersistentProperties),
           "PrivateBaseRelationProperty");
 
-      Assert.That(relationReflector.GetMetadata(_classDefinitions), Is.Not.Null);
+      Assert.That(relationReflector.GetMetadata(_typeDefinitions), Is.Not.Null);
     }
 
     [Test]
     public void GetMetadata_Mixed_TwoMixins ()
     {
-      CreateRelationReflectorForProperty(_multiMixinTargetClassDefinition, typeof(MixinAddingTwoReferencesToDerivedClass1), "MyDerived1");
+      CreateRelationReflectorForProperty(_multiMixinTargetTypeDefinition, typeof(MixinAddingTwoReferencesToDerivedClass1), "MyDerived1");
       var relationReflector1 = CreateRelationReflectorForProperty(
-          _multiMixinRelatedClassDefinition,
+          _multiMixinRelatedTypeDefinition,
           typeof(DerivedClassWithTwoBaseReferencesViaMixins),
           "MyBase1");
 
-      CreateRelationReflectorForProperty(_multiMixinTargetClassDefinition, typeof(MixinAddingTwoReferencesToDerivedClass2), "MyDerived2");
+      CreateRelationReflectorForProperty(_multiMixinTargetTypeDefinition, typeof(MixinAddingTwoReferencesToDerivedClass2), "MyDerived2");
       var relationReflector2 = CreateRelationReflectorForProperty(
-          _multiMixinRelatedClassDefinition,
+          _multiMixinRelatedTypeDefinition,
           typeof(DerivedClassWithTwoBaseReferencesViaMixins),
           "MyBase2");
 
-      var metadata1 = relationReflector1.GetMetadata(_classDefinitions);
+      var metadata1 = relationReflector1.GetMetadata(_typeDefinitions);
       Assert.That(metadata1, Is.Not.Null);
-      var metadata2 = relationReflector2.GetMetadata(_classDefinitions);
+      var metadata2 = relationReflector2.GetMetadata(_typeDefinitions);
       Assert.That(metadata2, Is.Not.Null);
     }
 
     [Test]
     public void GetMetadata_Mixed_PropertyAboveInheritanceRoot ()
     {
-      var classAboveInheritanceRoot = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationTargetForPersistentMixinAboveInheritanceRoot));
+      var classAboveInheritanceRoot = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationTargetForPersistentMixinAboveInheritanceRoot));
       CreateRelationReflectorForProperty(classAboveInheritanceRoot, typeof(RelationTargetForPersistentMixinAboveInheritanceRoot), "RelationProperty1");
       var relationReflector = CreateRelationReflectorForProperty(
-          _inheritanceRootInheritingMixinClassDefinition,
+          _inheritanceRootInheritingMixinTypeDefinition,
           typeof(MixinAddingPersistentPropertiesAboveInheritanceRoot),
           "PersistentRelationProperty");
-      _classDefinitions.Add(classAboveInheritanceRoot.ClassType, classAboveInheritanceRoot);
+      _typeDefinitions.Add(classAboveInheritanceRoot.Type, classAboveInheritanceRoot);
 
-      Assert.That(relationReflector.GetMetadata(_classDefinitions), Is.Not.Null);
+      Assert.That(relationReflector.GetMetadata(_typeDefinitions), Is.Not.Null);
     }
 
     private RelationReflector CreateRelationReflectorForProperty (
-        ClassDefinition classDefinition, Type declaringType, string propertyName)
+        TypeDefinition typeDefinition, Type declaringType, string propertyName)
     {
       var propertyInfo = PropertyInfoAdapter.Create(declaringType.GetProperty(propertyName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance));
       var propertyReflector = new PropertyReflector(
-          classDefinition,
+          typeDefinition,
           propertyInfo,
           new ReflectionBasedMemberInformationNameResolver(),
           PropertyMetadataProvider,
@@ -262,22 +262,22 @@ private RelationReflector CreateRelationReflectorForProperty (
       var propertyDefinition = propertyReflector.GetMetadata();
       var properties = new List<PropertyDefinition>();
       properties.Add(propertyDefinition);
-      var propertyDefinitionsOfClass = (PropertyDefinitionCollection)PrivateInvoke.GetNonPublicField(classDefinition, "_propertyDefinitions");
-      PrivateInvoke.SetNonPublicField(classDefinition, "_propertyDefinitions", null);
+      var propertyDefinitionsOfClass = (PropertyDefinitionCollection)PrivateInvoke.GetNonPublicField(typeDefinition, "_propertyDefinitions");
+      PrivateInvoke.SetNonPublicField(typeDefinition, "_propertyDefinitions", null);
       if (propertyDefinitionsOfClass != null)
         properties.AddRange(propertyDefinitionsOfClass);
-      classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(properties, true));
+      typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(properties, true));
 
-      var endPoint = MappingObjectFactory.CreateRelationEndPointDefinition(classDefinition, propertyInfo);
+      var endPoint = MappingObjectFactory.CreateRelationEndPointDefinition(typeDefinition, propertyInfo);
       var endPoints = new List<IRelationEndPointDefinition>();
       endPoints.Add(endPoint);
-      var endPointDefinitionsOfClass = (RelationEndPointDefinitionCollection)PrivateInvoke.GetNonPublicField(classDefinition, "_relationEndPoints");
-      PrivateInvoke.SetNonPublicField(classDefinition, "_relationEndPoints", null);
+      var endPointDefinitionsOfClass = (RelationEndPointDefinitionCollection)PrivateInvoke.GetNonPublicField(typeDefinition, "_relationEndPoints");
+      PrivateInvoke.SetNonPublicField(typeDefinition, "_relationEndPoints", null);
       if (endPointDefinitionsOfClass != null)
         endPoints.AddRange(endPointDefinitionsOfClass);
-      classDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(endPoints, true));
+      typeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(endPoints, true));
 
-      return new RelationReflector(classDefinition, propertyInfo, new ReflectionBasedMemberInformationNameResolver(), PropertyMetadataProvider);
+      return new RelationReflector(typeDefinition, propertyInfo, new ReflectionBasedMemberInformationNameResolver(), PropertyMetadataProvider);
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortExpressionDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortExpressionDefinitionTest.cs
index ce79111fd7..24e17fd2eb 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortExpressionDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortExpressionDefinitionTest.cs
@@ -26,7 +26,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.SortExpressions
   [TestFixture]
   public class SortExpressionDefinitionTest : StandardMappingTest
   {
-    private ClassDefinition _orderItemClassDefinition;
+    private TypeDefinition _orderItemTypeDefinition;
     private PropertyDefinition _productPropertyDefinition;
     private PropertyDefinition _positionPropertyDefinition;
 
@@ -34,9 +34,9 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _orderItemClassDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(OrderItem));
-      _productPropertyDefinition = _orderItemClassDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Product");
-      _positionPropertyDefinition = _orderItemClassDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Position");
+      _orderItemTypeDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(OrderItem));
+      _productPropertyDefinition = _orderItemTypeDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Product");
+      _positionPropertyDefinition = _orderItemTypeDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Position");
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortExpressionParserTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortExpressionParserTest.cs
index 01cdb847d6..ac783b9479 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortExpressionParserTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortExpressionParserTest.cs
@@ -26,7 +26,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.SortExpressions
   public class SortExpressionParserTest : StandardMappingTest
   {
     private SortExpressionParser _parser;
-    private ClassDefinition _orderItemClassDefinition;
+    private TypeDefinition _orderItemTypeDefinition;
     private PropertyDefinition _productPropertyDefinition;
     private PropertyDefinition _positionPropertyDefinition;
     private PropertyDefinition _orderPropertyDefinition;
@@ -35,12 +35,12 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _orderItemClassDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(OrderItem));
-      _productPropertyDefinition = _orderItemClassDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Product");
-      _positionPropertyDefinition = _orderItemClassDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Position");
-      _orderPropertyDefinition = _orderItemClassDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Order");
+      _orderItemTypeDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(OrderItem));
+      _productPropertyDefinition = _orderItemTypeDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Product");
+      _positionPropertyDefinition = _orderItemTypeDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Position");
+      _orderPropertyDefinition = _orderItemTypeDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Order");
 
-      _parser = new SortExpressionParser(_orderItemClassDefinition);
+      _parser = new SortExpressionParser(_orderItemTypeDefinition);
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortedPropertySpecificationTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortedPropertySpecificationTest.cs
index b1344baa37..6393789354 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortedPropertySpecificationTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/SortExpressions/SortedPropertySpecificationTest.cs
@@ -25,22 +25,22 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.SortExpressions
   [TestFixture]
   public class SortedPropertySpecificationTest : StandardMappingTest
   {
-    private ClassDefinition _orderItemClassDefinition;
+    private TypeDefinition _orderItemTypeDefinition;
     private PropertyDefinition _productPropertyDefinition;
     private PropertyDefinition _positionPropertyDefinition;
 
-    private ClassDefinition _customerClassDefinition;
+    private TypeDefinition _customerTypeDefinition;
     private PropertyDefinition _customerSincePropertyDefinition;
 
     public override void SetUp ()
     {
       base.SetUp();
-      _orderItemClassDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(OrderItem));
-      _productPropertyDefinition = _orderItemClassDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Product");
-      _positionPropertyDefinition = _orderItemClassDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Position");
+      _orderItemTypeDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(OrderItem));
+      _productPropertyDefinition = _orderItemTypeDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Product");
+      _positionPropertyDefinition = _orderItemTypeDefinition.GetMandatoryPropertyDefinition(typeof(OrderItem).FullName + ".Position");
 
-      _customerClassDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Customer));
-      _customerSincePropertyDefinition = _customerClassDefinition.GetMandatoryPropertyDefinition(typeof(Customer).FullName + ".CustomerSince");
+      _customerTypeDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Customer));
+      _customerSincePropertyDefinition = _customerTypeDefinition.GetMandatoryPropertyDefinition(typeof(Customer).FullName + ".CustomerSince");
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionChecker.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionChecker.cs
similarity index 71%
rename from Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionChecker.cs
rename to Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionChecker.cs
index 7bd297bd4b..274977d593 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionChecker.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionChecker.cs
@@ -22,64 +22,34 @@
 using Remotion.Data.DomainObjects.Persistence.Model;
 using Remotion.Data.DomainObjects.Persistence.Rdbms;
 using Remotion.Data.DomainObjects.Persistence.Rdbms.Model;
+using Remotion.Reflection;
 using Remotion.Utilities;
 
 namespace Remotion.Data.DomainObjects.UnitTests.Mapping
 {
-  public class ClassDefinitionChecker
+  public class TypeDefinitionChecker
   {
-    public void Check (ClassDefinition expectedDefinition, ClassDefinition actualDefinition)
+    public void Check (TypeDefinition expectedDefinition, TypeDefinition actualDefinition)
     {
       ArgumentUtility.CheckNotNull("expectedDefinition", expectedDefinition);
       ArgumentUtility.CheckNotNull("actualDefinition", actualDefinition);
 
-      Assert.AreEqual(expectedDefinition.ID, actualDefinition.ID, "IDs of class definitions do not match.");
-
-      Assert.AreEqual(
-          expectedDefinition.ClassType,
-          actualDefinition.ClassType,
-          "ClassType of class definition '{0}' does not match.",
-          expectedDefinition.ID);
-
-      Assert.AreEqual(
-          expectedDefinition.IsClassTypeResolved,
-          actualDefinition.IsClassTypeResolved,
-          "IsClassTypeResolved of class definition '{0}' does not match.",
-          expectedDefinition.ID);
-
-      Assert.AreEqual(
-          expectedDefinition.IsAbstract,
-          actualDefinition.IsAbstract,
-          "IsAbstract of class definition '{0}' does not match.",
-          expectedDefinition.ID);
-
-      Assert.AreSame(
-          expectedDefinition.InstanceCreator,
-          actualDefinition.InstanceCreator,
-          "Instance creator of class definition '{0}' is not the expected object.",
-          actualDefinition.ID);
-
-      if (expectedDefinition.BaseClass == null)
+      if (expectedDefinition is ClassDefinition expectedClassDefinition)
       {
-        Assert.IsNull(actualDefinition.BaseClass, "actualDefinition.BaseClass of class definition '{0}' is not null.", expectedDefinition.ID);
+        if (actualDefinition is not ClassDefinition actualClassDefinition)
+          throw new InvalidOperationException("The two type definitions must have a matching type.");
+
+        CheckClassDefinition(expectedClassDefinition, actualClassDefinition);
       }
       else
       {
-        Assert.IsNotNull(actualDefinition.BaseClass, "actualDefinition.BaseClass of class definition '{0}' is null.", expectedDefinition.ID);
-
-        Assert.AreEqual(
-            expectedDefinition.BaseClass.ID,
-            actualDefinition.BaseClass.ID,
-            "BaseClass of class definition '{0}' does not match.",
-            expectedDefinition.ID);
+        Assert.Fail("Unsupported type definition cannot be checked.");
       }
-
-      CheckPropertyDefinitions(expectedDefinition.MyPropertyDefinitions, actualDefinition.MyPropertyDefinitions, expectedDefinition);
     }
 
     public void Check (
-        IEnumerable<ClassDefinition> expectedDefinitions,
-        IDictionary<Type, ClassDefinition> actualDefinitions,
+        IEnumerable<TypeDefinition> expectedDefinitions,
+        IDictionary<Type, TypeDefinition> actualDefinitions,
         bool checkRelations,
         bool ignoreUnknown)
     {
@@ -91,41 +61,54 @@ public void Check (
 
       foreach (var expectedDefinition in expectedDefinitions)
       {
-        var actualDefinition = actualDefinitions[expectedDefinition.ClassType];
-        Check(expectedDefinition, actualDefinition);
-        CheckDerivedClasses(expectedDefinition, actualDefinition);
+        var actualDefinition = actualDefinitions[expectedDefinition.Type];
+        if (expectedDefinition is ClassDefinition expectedClassDefinition)
+        {
+          if (actualDefinition is not ClassDefinition actualClassDefinition)
+          {
+            Assert.Fail("The two type definitions must have a matching type.");
+            return;
+          }
+
+          CheckClassDefinition(expectedClassDefinition, actualClassDefinition);
+          CheckDerivedClasses(expectedClassDefinition, actualClassDefinition);
+        }
+        else
+        {
+          Assert.Fail("Unsupported type definition cannot be checked.");
+        }
       }
 
       if (checkRelations)
         CheckRelationEndPoints(expectedDefinitions, actualDefinitions);
     }
 
-    public void CheckRelationEndPoints (IEnumerable<ClassDefinition> expectedDefinitions, IDictionary<Type, ClassDefinition> actualDefinitions)
+    public void CheckRelationEndPoints (IEnumerable<TypeDefinition> expectedDefinitions, IDictionary<Type, TypeDefinition> actualDefinitions)
     {
       ArgumentUtility.CheckNotNull("expectedDefinitions", expectedDefinitions);
       ArgumentUtility.CheckNotNull("actualDefinitions", actualDefinitions);
 
       foreach (var expectedDefinition in expectedDefinitions)
       {
-        var actualDefinition = actualDefinitions[expectedDefinition.ClassType];
+        var actualDefinition = actualDefinitions[expectedDefinition.Type];
         var endPointDefinitionChecker = new RelationEndPointDefinitionChecker();
         endPointDefinitionChecker.Check(expectedDefinition.MyRelationEndPointDefinitions, actualDefinition.MyRelationEndPointDefinitions, true);
       }
     }
 
-    public void CheckPersistenceModel (IEnumerable<ClassDefinition> expectedDefinitions, IDictionary<Type, ClassDefinition> actualDefinitions)
+    public void CheckPersistenceModel (IEnumerable<TypeDefinition> expectedDefinitions, IDictionary<Type, TypeDefinition> actualDefinitions)
     {
       ArgumentUtility.CheckNotNull("expectedDefinitions", expectedDefinitions);
       ArgumentUtility.CheckNotNull("actualDefinitions", actualDefinitions);
 
       foreach (var expectedDefinition in expectedDefinitions)
       {
-        var actualDefinition = actualDefinitions[expectedDefinition.ClassType];
+        var actualDefinition = actualDefinitions[expectedDefinition.Type];
         CheckPersistenceModel(expectedDefinition, actualDefinition);
       }
     }
 
-    public void CheckPersistenceModel (ClassDefinition expectedDefinition, ClassDefinition actualDefinition)
+    public void CheckPersistenceModel (TypeDefinition expectedDefinition, TypeDefinition actualDefinition)
     {
       ArgumentUtility.CheckNotNull("expectedDefinition", expectedDefinition);
       ArgumentUtility.CheckNotNull("actualDefinition", actualDefinition);
@@ -133,8 +116,8 @@ public void CheckPersistenceModel (ClassDefinition expectedDefinition, ClassDefi
       Assert.AreEqual(
           expectedDefinition.StorageEntityDefinition.StorageProviderDefinition,
           actualDefinition.StorageEntityDefinition.StorageProviderDefinition,
-          "StorageProviderDefinition of class definition '{0}' does not match. ",
-          expectedDefinition.ID);
+          "StorageProviderDefinition of type definition '{0}' does not match. ",
+          expectedDefinition.Type.GetFullNameSafe());
 
       // We can't check much since FakeMappingConfiguration always creates fake entity definitions, only the entity name is defined.
       var expectedEntityName = GetEntityName(expectedDefinition.StorageEntityDefinition);
@@ -143,14 +126,17 @@ public void CheckPersistenceModel (ClassDefinition expectedDefinition, ClassDefi
       Assert.AreEqual(
           expectedEntityName,
           actualEntityName,
-          "Entity name of class definition '{0}' does not match.",
-          expectedDefinition.ID);
+          "Entity name of type definition '{0}' does not match.",
+          expectedDefinition.Type.GetFullNameSafe());
 
       foreach (PropertyDefinition expectedPropertyDefinition in expectedDefinition.MyPropertyDefinitions)
       {
         PropertyDefinition actualPropertyDefinition = actualDefinition.MyPropertyDefinitions[expectedPropertyDefinition.PropertyName];
         Assert.IsNotNull(
-            actualPropertyDefinition, "Class '{0}' has no property '{1}'.", expectedDefinition.ID, expectedPropertyDefinition.PropertyName);
+            actualPropertyDefinition,
+            "Type '{0}' has no property '{1}'.",
+            expectedDefinition.Type.GetFullNameSafe(),
+            expectedPropertyDefinition.PropertyName);
 
         if (expectedPropertyDefinition.StorageClass == StorageClass.Persistent)
         {
@@ -161,13 +147,62 @@ public void CheckPersistenceModel (ClassDefinition expectedDefinition, ClassDefi
           Assert.AreEqual(
               expectedColumnName,
               actualColumnName,
-              "Column name of property definition '{0}' (class definition: '{1}') does not match.",
+              "Column name of property definition '{0}' (type definition: '{1}') does not match.",
               expectedPropertyDefinition.PropertyName,
-              actualDefinition.ID);
+              actualDefinition.Type.GetFullNameSafe());
         }
       }
     }
 
+    private void CheckClassDefinition (ClassDefinition expectedDefinition, ClassDefinition actualDefinition)
+    {
+      ArgumentUtility.CheckNotNull("expectedDefinition", expectedDefinition);
+      ArgumentUtility.CheckNotNull("actualDefinition", actualDefinition);
+
+      Assert.AreEqual(expectedDefinition.ID, actualDefinition.ID, "IDs of class definitions do not match.");
+
+      Assert.AreEqual(
+          expectedDefinition.Type,
+          actualDefinition.Type,
+          "Type of class definition '{0}' does not match.",
+          expectedDefinition.ID);
+
+      Assert.AreEqual(
+          expectedDefinition.IsTypeResolved,
+          actualDefinition.IsTypeResolved,
+          "IsResolved of class definition '{0}' does not match.",
+          expectedDefinition.ID);
+
+      Assert.AreEqual(
+          expectedDefinition.IsAbstract,
+          actualDefinition.IsAbstract,
+          "IsAbstract of class definition '{0}' does not match.",
+          expectedDefinition.ID);
+
+      Assert.AreSame(
+          expectedDefinition.InstanceCreator,
+          actualDefinition.InstanceCreator,
+          "Instance creator of class definition '{0}' is not the expected object.",
+          actualDefinition.ID);
+
+      if (expectedDefinition.BaseClass == null)
+      {
+        Assert.IsNull(actualDefinition.BaseClass, "actualDefinition.BaseClass of class definition '{0}' is not null.", expectedDefinition.ID);
+      }
+      else
+      {
+        Assert.IsNotNull(actualDefinition.BaseClass, "actualDefinition.BaseClass of class definition '{0}' is null.", expectedDefinition.ID);
+
+        Assert.AreEqual(
+            expectedDefinition.BaseClass.ID,
+            actualDefinition.BaseClass.ID,
+            "BaseClass of class definition '{0}' does not match.",
+            expectedDefinition.ID);
+      }
+
+      CheckPropertyDefinitions(expectedDefinition.MyPropertyDefinitions, actualDefinition.MyPropertyDefinitions, expectedDefinition);
+    }
+
     public void CheckDerivedClasses (ClassDefinition expectedDefinition, ClassDefinition actualDefinition)
     {
       ArgumentUtility.CheckNotNull("expectedDefinition", expectedDefinition);
@@ -201,74 +236,74 @@ private void CheckDerivedClasses (
     private void CheckPropertyDefinitions (
         PropertyDefinitionCollection expectedDefinitions,
         PropertyDefinitionCollection actualDefinitions,
-        ClassDefinition expectedClassDefinition)
+        TypeDefinition expectedTypeDefinition)
     {
       Assert.AreEqual(
           expectedDefinitions.Count,
           actualDefinitions.Count,
-          "Number of property definitions in class definition '{0}' does not match. Expected: {1}",
-          expectedClassDefinition.ID,
+          "Number of property definitions in type definition '{0}' does not match. Expected: {1}",
+          expectedTypeDefinition.Type.GetFullNameSafe(),
           string.Join(", ", actualDefinitions.Select(pd => pd.PropertyName)));
 
       foreach (PropertyDefinition expectedDefinition in expectedDefinitions)
       {
         PropertyDefinition actualDefinition = actualDefinitions[expectedDefinition.PropertyName];
-        Assert.IsNotNull(actualDefinition, "Class '{0}' has no property '{1}'.", expectedClassDefinition.ID, expectedDefinition.PropertyName);
-        CheckPropertyDefinition(expectedDefinition, actualDefinition, expectedClassDefinition);
+        Assert.IsNotNull(actualDefinition, "Type '{0}' has no property '{1}'.", expectedTypeDefinition.Type.GetFullNameSafe(), expectedDefinition.PropertyName);
+        CheckPropertyDefinition(expectedDefinition, actualDefinition, expectedTypeDefinition);
       }
     }
 
     private void CheckPropertyDefinition (
         PropertyDefinition expectedDefinition,
         PropertyDefinition actualDefinition,
-        ClassDefinition classDefinition)
+        TypeDefinition typeDefinition)
     {
       Assert.AreEqual(
           expectedDefinition.PropertyName,
           actualDefinition.PropertyName,
-          "PropertyNames of property definitions (class definition: '{0}') do not match.",
-          classDefinition.ID);
+          "PropertyNames of property definitions (type definition: '{0}') do not match.",
+          typeDefinition.Type.GetFullNameSafe());
 
       Assert.AreEqual(
-          expectedDefinition.ClassDefinition.ID,
-          actualDefinition.ClassDefinition.ID,
-          "ClassDefinitionID of property definition '{0}' does not match.",
+          expectedDefinition.TypeDefinition.Type,
+          actualDefinition.TypeDefinition.Type,
+          "Type of property definition '{0}' does not match.",
           expectedDefinition.PropertyName);
 
       Assert.AreEqual(
           expectedDefinition.StorageClass,
           actualDefinition.StorageClass,
-          "StorageClass of property definition '{0}' (class definition: '{1}') does not match.",
+          "StorageClass of property definition '{0}' (type definition: '{1}') does not match.",
           expectedDefinition.PropertyName,
-          classDefinition.ID);
+          typeDefinition.Type.GetFullNameSafe());
 
       Assert.AreEqual(
           expectedDefinition.MaxLength,
           actualDefinition.MaxLength,
-          "MaxLength of property definition '{0}' (class definition: '{1}') does not match.",
+          "MaxLength of property definition '{0}' (type definition: '{1}') does not match.",
           expectedDefinition.PropertyName,
-          classDefinition.ID);
+          typeDefinition.Type.GetFullNameSafe());
 
       Assert.AreEqual(
           expectedDefinition.PropertyType,
           actualDefinition.PropertyType,
-          "PropertyType of property definition '{0}' (class definition: '{1}') does not match.",
+          "PropertyType of property definition '{0}' (type definition: '{1}') does not match.",
           expectedDefinition.PropertyName,
-          classDefinition.ID);
+          typeDefinition.Type.GetFullNameSafe());
 
       Assert.AreEqual(
           expectedDefinition.IsNullable,
           actualDefinition.IsNullable,
-          "IsNullable of property definition '{0}' (class definition: '{1}') does not match",
+          "IsNullable of property definition '{0}' (type definition: '{1}') does not match",
           expectedDefinition.PropertyName,
-          classDefinition.ID);
+          typeDefinition.Type.GetFullNameSafe());
 
       Assert.AreEqual(
           expectedDefinition.IsObjectID,
           actualDefinition.IsObjectID,
-          "IsObjectID of property definition '{0}' (class definition: '{1}') does not match.",
+          "IsObjectID of property definition '{0}' (type definition: '{1}') does not match.",
           expectedDefinition.PropertyName,
-          classDefinition.ID);
+          typeDefinition.Type.GetFullNameSafe());
     }
 
     private string GetEntityName (IStorageEntityDefinition storageEntityDefinition)
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionHierarchyTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionHierarchyTest.cs
new file mode 100644
index 0000000000..823f1975a1
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionHierarchyTest.cs
@@ -0,0 +1,105 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping
+{
+  [TestFixture]
+  public class TypeDefinitionHierarchyTest
+  {
+    [Test]
+    public void ArePartOfSameHierarchy ()
+    {
+      var iOther = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      var iExtendedOther = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(extendedInterfaces: new[] { iOther });
+      var iDomainBase = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      var domainBase = ClassDefinitionObjectMother.CreateClassDefinition("Base", implementedInterfaces: new[] { iDomainBase });
+      var person = ClassDefinitionObjectMother.CreateClassDefinition("Person", baseClass: domainBase);
+      var customer = ClassDefinitionObjectMother.CreateClassDefinition("Customer", baseClass: person, implementedInterfaces: new[] { iExtendedOther });
+      var employee = ClassDefinitionObjectMother.CreateClassDefinition("Employee", baseClass: person);
+      var iCompany = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(extendedInterfaces: new[] { iDomainBase });
+
+      var separate = ClassDefinitionObjectMother.CreateClassDefinition("Separate");
+
+      Assert.That(TypeDefinitionHierarchy.ArePartOfSameHierarchy(separate, iOther), Is.False);
+      Assert.That(TypeDefinitionHierarchy.ArePartOfSameHierarchy(iOther, separate), Is.False);
+      Assert.That(TypeDefinitionHierarchy.ArePartOfSameHierarchy(iOther, person), Is.False);
+      Assert.That(TypeDefinitionHierarchy.ArePartOfSameHierarchy(person, iOther), Is.False);
+
+      Assert.That(TypeDefinitionHierarchy.ArePartOfSameHierarchy(customer, employee), Is.True);
+      Assert.That(TypeDefinitionHierarchy.ArePartOfSameHierarchy(employee, customer), Is.True);
+      Assert.That(TypeDefinitionHierarchy.ArePartOfSameHierarchy(employee, iCompany), Is.True);
+      Assert.That(TypeDefinitionHierarchy.ArePartOfSameHierarchy(iCompany, employee), Is.True);
+    }
+
+    [Test]
+    public void ArePartOfSameHierarchy_WithSameTypeDefinition_ReturnsTrue ()
+    {
+      var typeDefinition = TypeDefinitionObjectMother.CreateInterfaceDefinition();
+
+      Assert.That(TypeDefinitionHierarchy.ArePartOfSameHierarchy(typeDefinition, typeDefinition), Is.True);
+    }
+
+    [Test]
+    public void GetHierarchyRoots ()
+    {
+      var iOther = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      var iExtendedOther = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(extendedInterfaces: new[] { iOther });
+      var iDomainBase = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      var domainBase = ClassDefinitionObjectMother.CreateClassDefinition("Base", implementedInterfaces: new[] { iDomainBase });
+      var person = ClassDefinitionObjectMother.CreateClassDefinition("Person", baseClass: domainBase);
+      var customer = ClassDefinitionObjectMother.CreateClassDefinition("Customer", baseClass: person, implementedInterfaces: new[] { iExtendedOther });
+      var employee = ClassDefinitionObjectMother.CreateClassDefinition("Employee", baseClass: person);
+
+      var separate = ClassDefinitionObjectMother.CreateClassDefinition("Separate");
+
+      var hierarchyRoots = TypeDefinitionHierarchy.GetHierarchyRoots(new[] { customer, employee, separate });
+
+      Assert.That(hierarchyRoots, Is.EqualTo(new TypeDefinition[] { domainBase, iDomainBase, iOther, separate }));
+    }
+
+    [Test]
+    public void GetDescendantsAndSelf ()
+    {
+      var iDomainBase = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      var iExternal = InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties(extendedInterfaces: new[] { iDomainBase });
+      var domainBase = ClassDefinitionObjectMother.CreateClassDefinition("DomainBase", implementedInterfaces: new[] { iDomainBase });
+      var person = ClassDefinitionObjectMother.CreateClassDefinition("Person", baseClass: domainBase);
+      var customer = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties("Customer", baseClass: person);
+      var organizationalUnit = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties("OrganizationalUnit", baseClass: domainBase);
+      iDomainBase.SetExtendingInterfaces(new[] { iExternal });
+      iDomainBase.SetImplementingClasses(new[] { domainBase });
+      domainBase.SetDerivedClasses(new[] { person, organizationalUnit });
+      person.SetDerivedClasses(new[] { customer });
+
+      var actual = TypeDefinitionHierarchy.GetDescendantsAndSelf(iDomainBase);
+      var expected = new TypeDefinition[]
+                     {
+                         iDomainBase,
+                         domainBase,
+                         person,
+                         customer,
+                         organizationalUnit,
+                         iExternal
+                     };
+
+      Assert.That(actual, Is.EqualTo(expected));
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionObjectMother.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionObjectMother.cs
new file mode 100644
index 0000000000..2a1f26093e
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionObjectMother.cs
@@ -0,0 +1,137 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using System.Collections.Generic;
+using Moq;
+using Remotion.Data.DomainObjects.Infrastructure;
+using Remotion.Data.DomainObjects.Mapping;
+using Remotion.Data.DomainObjects.Persistence.Configuration;
+using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration;
+using Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.Model;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping
+{
+  public static class TypeDefinitionObjectMother
+  {
+    public static TypeDefinition CreateClassDefinition (
+        string id = null,
+        Type classType = null,
+        bool isAbstract = false,
+        ClassDefinition baseClass = null,
+        IEnumerable<InterfaceDefinition> implementedInterfaces = null,
+        Type storageGroupType = null,
+        DefaultStorageClass? defaultStorageClass = null,
+        IPersistentMixinFinder persistentMixinFinder = null,
+        IDomainObjectCreator instanceCreator = null)
+    {
+      return ClassDefinitionObjectMother.CreateClassDefinition(
+          id,
+          classType,
+          isAbstract,
+          baseClass,
+          implementedInterfaces,
+          storageGroupType,
+          defaultStorageClass,
+          persistentMixinFinder,
+          instanceCreator);
+    }
+
+    public static TypeDefinition CreateClassDefinitionWithDefaultProperties (
+        string id = null,
+        Type classType = null,
+        bool isAbstract = false,
+        ClassDefinition baseClass = null,
+        IEnumerable<InterfaceDefinition> implementedInterfaces = null,
+        Type storageGroupType = null,
+        DefaultStorageClass? defaultStorageClass = null,
+        IPersistentMixinFinder persistentMixinFinder = null,
+        IDomainObjectCreator instanceCreator = null)
+    {
+      return ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties(
+          id,
+          classType,
+          isAbstract,
+          baseClass,
+          implementedInterfaces,
+          storageGroupType,
+          defaultStorageClass,
+          persistentMixinFinder,
+          instanceCreator);
+    }
+
+    public static TypeDefinition CreateClassDefinition_WithEmptyMembers_AndDerivedClasses (string id = null, Type classType = null, ClassDefinition baseClass = null)
+    {
+      return ClassDefinitionObjectMother.CreateClassDefinition_WithEmptyMembers_AndDerivedClasses(
+          id,
+          classType,
+          baseClass);
+    }
+
+    public static TypeDefinition CreateClassDefinitionWithTable (
+        StorageProviderDefinition storageProviderDefinition,
+        string id = null,
+        Type classType = null,
+        bool isAbstract = false,
+        ClassDefinition baseClass = null,
+        IEnumerable<InterfaceDefinition> implementedInterfaces = null,
+        Type storageGroupType = null,
+        DefaultStorageClass? defaultStorageClass = null,
+        IPersistentMixinFinder persistentMixinFinder = null,
+        IDomainObjectCreator instanceCreator = null)
+    {
+      return ClassDefinitionObjectMother.CreateClassDefinitionWithTable(
+          storageProviderDefinition,
+          id,
+          classType,
+          isAbstract,
+          baseClass,
+          implementedInterfaces,
+          storageGroupType,
+          defaultStorageClass,
+          persistentMixinFinder,
+          instanceCreator);
+    }
+
+    public static TypeDefinition CreateClassDefinitionWithMixins (Type type, params Type[] mixins)
+    {
+      return ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(type, mixins);
+    }
+
+    public static TypeDefinition CreateClassDefinitionWithMixinsAndDefaultProperties (Type type, params Type[] mixins)
+    {
+      return ClassDefinitionObjectMother.CreateClassDefinitionWithMixinsWithDefaultProperties(type, mixins);
+    }
+
+    public static TypeDefinition CreateInterfaceDefinition (
+        Type type = null,
+        IEnumerable<InterfaceDefinition> extendedInterfaces = null,
+        Type storageGroupType = null,
+        DefaultStorageClass? defaultStorageClass = null)
+    {
+      return InterfaceDefinitionObjectMother.CreateInterfaceDefinition(type, extendedInterfaces, storageGroupType, defaultStorageClass);
+    }
+
+    public static TypeDefinition CreateInterfaceDefinitionWithDefaultProperties (
+        Type type = null,
+        IEnumerable<InterfaceDefinition> extendedInterfaces = null,
+        Type storageGroupType = null,
+        DefaultStorageClass? defaultStorageClass = null)
+    {
+      return InterfaceDefinitionObjectMother.CreateInterfaceDefinitionWithDefaultProperties(type, extendedInterfaces, storageGroupType, defaultStorageClass);
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionTest.cs
new file mode 100644
index 0000000000..7862ad3e88
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionTest.cs
@@ -0,0 +1,506 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using System.Collections.Generic;
+using JetBrains.Annotations;
+using Moq;
+using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
+using Remotion.Data.DomainObjects.Persistence.Rdbms.Model;
+using Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.Model;
+using Remotion.Development.NUnit.UnitTesting;
+using Remotion.Reflection;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping
+{
+  [TestFixture]
+  public class TypeDefinitionTest : MappingReflectionTestBase
+  {
+    private interface IDomainBase
+    {
+    }
+
+    private interface IPerson : IDomainBase
+    {
+    }
+
+    private interface ICustomer : IPerson
+    {
+    }
+
+    private interface IOrganizationalUnit : IDomainBase
+    {
+    }
+
+    private class TestableTypeDefinition : TypeDefinition
+    {
+      public Action<IEnumerable<PropertyDefinition>> CheckPropertyDefinitionsCallback { get; set; }
+
+      public Action<IEnumerable<IRelationEndPointDefinition>> CheckRelationEndPointDefinitionsCallback { get; set; }
+
+      public Func<PropertyDefinitionCollection> CreatePropertyDefinitionCollectionCallback { get; set; }
+
+      public Func<RelationEndPointDefinitionCollection> CreateRelationEndPointDefinitionCollectionCallback { get; set; }
+
+      public TestableTypeDefinition (
+          [NotNull] Type type,
+          [CanBeNull] Type storageGroupType,
+          DefaultStorageClass defaultStorageClass)
+          : base(type, storageGroupType, defaultStorageClass)
+      {
+      }
+
+      public override void Accept (ITypeDefinitionVisitor visitor) => throw new NotImplementedException();
+
+      public override T Accept<T> (ITypeDefinitionVisitor<T> visitor) where T : default => throw new NotImplementedException();
+
+      public override bool IsPartOfInheritanceHierarchy => throw new NotImplementedException();
+
+      public override bool IsAssignableFrom (TypeDefinition other) => throw new NotImplementedException();
+
+      protected override void CheckPropertyDefinitions (IEnumerable<PropertyDefinition> propertyDefinitions)
+      {
+        CheckPropertyDefinitionsCallback?.Invoke(propertyDefinitions);
+      }
+
+      protected override void CheckRelationEndPointDefinitions (IEnumerable<IRelationEndPointDefinition> relationEndPoints)
+      {
+        CheckRelationEndPointDefinitionsCallback?.Invoke(relationEndPoints);
+      }
+
+      protected override PropertyDefinitionCollection CreatePropertyDefinitionCollection ()
+      {
+        return CreatePropertyDefinitionCollectionCallback?.Invoke();
+      }
+
+      protected override RelationEndPointDefinitionCollection CreateRelationEndPointDefinitionCollection ()
+      {
+        return CreateRelationEndPointDefinitionCollectionCallback?.Invoke();
+      }
+
+      public void SetupForReadOnlyUsage ()
+      {
+        SetPropertyDefinitions(new PropertyDefinitionCollection());
+        SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+        SetStorageEntity(new FakeStorageEntityDefinition(new UnitTestStorageProviderStubDefinition("stub"), "stub"));
+      }
+    }
+
+    private UnitTestStorageProviderStubDefinition _storageProviderDefinition;
+
+    private TestableTypeDefinition _domainBaseTypeDefinition;
+    private TestableTypeDefinition _personTypeDefinition;
+    private TestableTypeDefinition _customerTypeDefinition;
+    private TestableTypeDefinition _organizationalUnitTypeDefinition;
+
+    private Mock<Action<IEnumerable<PropertyDefinition>>> _checkPropertyDefinitionsMock;
+    private Mock<Action<IEnumerable<IRelationEndPointDefinition>>> _checkRelationEndPointDefinitionsMock;
+    private Mock<Func<PropertyDefinitionCollection>> _createPropertyDefinitionCollectionMock;
+    private Mock<Func<RelationEndPointDefinitionCollection>> _createRelationEndpointCollectionMock;
+
+    public override void SetUp ()
+    {
+      base.SetUp();
+
+      _storageProviderDefinition = new UnitTestStorageProviderStubDefinition("DefaultStorageProvider");
+
+      _checkPropertyDefinitionsMock = new Mock<Action<IEnumerable<PropertyDefinition>>>();
+      _checkRelationEndPointDefinitionsMock = new Mock<Action<IEnumerable<IRelationEndPointDefinition>>>();
+      _createPropertyDefinitionCollectionMock = new Mock<Func<PropertyDefinitionCollection>>();
+      _createRelationEndpointCollectionMock = new Mock<Func<RelationEndPointDefinitionCollection>>();
+
+      _domainBaseTypeDefinition = new TestableTypeDefinition(typeof(IDomainBase), null, DefaultStorageClass.Persistent);
+      _domainBaseTypeDefinition.CheckPropertyDefinitionsCallback = _checkPropertyDefinitionsMock.Object;
+      _domainBaseTypeDefinition.CheckRelationEndPointDefinitionsCallback = _checkRelationEndPointDefinitionsMock.Object;
+      _domainBaseTypeDefinition.CreatePropertyDefinitionCollectionCallback = _createPropertyDefinitionCollectionMock.Object;
+      _domainBaseTypeDefinition.CreateRelationEndPointDefinitionCollectionCallback = _createRelationEndpointCollectionMock.Object;
+
+      _personTypeDefinition = new TestableTypeDefinition(typeof(IPerson), null, DefaultStorageClass.Persistent);
+      _customerTypeDefinition = new TestableTypeDefinition(typeof(ICustomer), null, DefaultStorageClass.Persistent);
+      _organizationalUnitTypeDefinition = new TestableTypeDefinition(typeof(IOrganizationalUnit), null, DefaultStorageClass.Persistent);
+    }
+
+    [Test]
+    public void Initialize ()
+    {
+      var actual = new TestableTypeDefinition(
+          typeof(IDomainBase),
+          null,
+          DefaultStorageClass.Transaction);
+
+      Assert.That(actual.Type, Is.SameAs(typeof(IDomainBase)));
+      Assert.That(actual.StorageGroupType, Is.Null);
+      Assert.That(actual.DefaultStorageClass, Is.EqualTo(DefaultStorageClass.Transaction));
+
+      Assert.That(actual.HasStorageEntityDefinitionBeenSet, Is.False);
+      Assert.That(
+          () => actual.StorageEntityDefinition,
+          Throws.InvalidOperationException
+              .With.Message.EqualTo(
+                  "StorageEntityDefinition has not been set for type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TypeDefinitionTest+IDomainBase'."));
+
+      Assert.That(
+          () => actual.MyPropertyDefinitions,
+          Throws.InvalidOperationException
+              .With.Message.EqualTo(
+                  "No property definitions have been set for type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TypeDefinitionTest+IDomainBase'."));
+      Assert.That(
+          () => actual.MyRelationEndPointDefinitions,
+          Throws.InvalidOperationException
+              .With.Message.EqualTo(
+                  "No relation end point definitions have been set for type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TypeDefinitionTest+IDomainBase'."));
+
+      Assert.That(actual.PropertyAccessorDataCache, Is.Not.Null);
+      Assert.That(actual.IsReadOnly, Is.False);
+    }
+
+    [Test]
+    public void SetStorageEntity ()
+    {
+      var tableDefinition = TableDefinitionObjectMother.Create(_storageProviderDefinition, new EntityNameDefinition(null, "Tablename"));
+      Assert.That(_domainBaseTypeDefinition.HasStorageEntityDefinitionBeenSet, Is.False);
+
+      _domainBaseTypeDefinition.SetStorageEntity(tableDefinition);
+
+      Assert.That(_domainBaseTypeDefinition.StorageEntityDefinition, Is.SameAs(tableDefinition));
+      Assert.That(_domainBaseTypeDefinition.HasStorageEntityDefinitionBeenSet, Is.True);
+    }
+
+    [Test]
+    public void SetStorageEntity_ReadOnly_Throws ()
+    {
+      var tableDefinition = TableDefinitionObjectMother.Create(_storageProviderDefinition, new EntityNameDefinition(null, "Tablename"));
+      _domainBaseTypeDefinition.SetupForReadOnlyUsage();
+      _domainBaseTypeDefinition.SetReadOnly();
+
+      Assert.That(
+          () => _domainBaseTypeDefinition.SetStorageEntity(tableDefinition),
+          Throws.InstanceOf<NotSupportedException>()
+              .With.Message.EqualTo("Type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TypeDefinitionTest+IDomainBase' is read-only."));
+    }
+
+    [Test]
+    public void GetPropertyDefinitions ()
+    {
+      var collection = new PropertyDefinitionCollection();
+      _createPropertyDefinitionCollectionMock.Setup(_ => _()).Returns(collection);
+
+      var actualCollection = _domainBaseTypeDefinition.GetPropertyDefinitions();
+
+      Assert.That(actualCollection, Is.SameAs(collection));
+    }
+
+    [Test]
+    public void GetPropertyDefinitions_SecondCall_ReturnsNewCollection ()
+    {
+      _createPropertyDefinitionCollectionMock.Setup(_ => _()).Returns(() => new PropertyDefinitionCollection());
+
+      var result1 = _domainBaseTypeDefinition.GetPropertyDefinitions();
+      var result2 = _domainBaseTypeDefinition.GetPropertyDefinitions();
+
+      Assert.That(result1, Is.Not.Null);
+      Assert.That(result1, Is.Not.SameAs(result2));
+    }
+
+    [Test]
+    public void GetPropertyDefinitions_SecondCallAndReadOnly_ReturnsCachedResult ()
+    {
+      _createPropertyDefinitionCollectionMock.Setup(_ => _()).Returns(() => new PropertyDefinitionCollection());
+      _domainBaseTypeDefinition.SetupForReadOnlyUsage();
+      _domainBaseTypeDefinition.SetReadOnly();
+
+      var result1 = _domainBaseTypeDefinition.GetPropertyDefinitions();
+      var result2 = _domainBaseTypeDefinition.GetPropertyDefinitions();
+
+      Assert.That(result1, Is.Not.Null);
+      Assert.That(result1, Is.SameAs(result2));
+    }
+
+    [Test]
+    public void GetPropertyDefinition ()
+    {
+      var propertyInformation = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_domainBaseTypeDefinition);
+      _createPropertyDefinitionCollectionMock.Setup(_ => _()).Returns(new PropertyDefinitionCollection(new []{propertyInformation}, true));
+
+      Assert.That(
+          _domainBaseTypeDefinition.GetPropertyDefinition("Test"),
+          Is.SameAs(propertyInformation));
+    }
+
+    [Test]
+    public void GetPropertyDefinition_EmptyPropertyName_Throws ()
+    {
+      Assert.That(
+          () => _domainBaseTypeDefinition.GetPropertyDefinition(string.Empty),
+          Throws.ArgumentException
+              .With.ArgumentExceptionMessageEqualTo("Parameter 'propertyName' cannot be empty.", "propertyName"));
+    }
+
+    [Test]
+    public void GetPropertyDefinition_NonExistingProperty_ReturnsNull ()
+    {
+      _createPropertyDefinitionCollectionMock.Setup(_ => _()).Returns(new PropertyDefinitionCollection());
+
+      Assert.That(_domainBaseTypeDefinition.GetPropertyDefinition("dummy"), Is.Null);
+    }
+
+    [Test]
+    public void GetMandatoryPropertyDefinition_NonExistingProperty_Throws ()
+    {
+      _createPropertyDefinitionCollectionMock.Setup(_ => _()).Returns(new PropertyDefinitionCollection());
+
+      Assert.That(
+          () => _domainBaseTypeDefinition.GetMandatoryPropertyDefinition("dummy"),
+          Throws.TypeOf<MappingException>()
+              .With.Message.EqualTo(
+                  "Type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TypeDefinitionTest+IDomainBase' "
+                  + "does not contain the property 'dummy'."));
+    }
+
+    [Test]
+    public void SetPropertyDefinitions ()
+    {
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_domainBaseTypeDefinition);
+
+      _checkPropertyDefinitionsMock
+          .Setup(_ => _(new[] { propertyDefinition }))
+          .Callback(
+              () => { Assert.That(() => _domainBaseTypeDefinition.MyPropertyDefinitions, Throws.Exception); }
+          )
+          .Verifiable();
+
+      _domainBaseTypeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, false));
+
+      Assert.That(_domainBaseTypeDefinition.MyPropertyDefinitions.Count, Is.EqualTo(1));
+      Assert.That(_domainBaseTypeDefinition.MyPropertyDefinitions[0], Is.SameAs(propertyDefinition));
+      Assert.That(_domainBaseTypeDefinition.MyPropertyDefinitions.IsReadOnly, Is.True);
+
+      _checkPropertyDefinitionsMock.Verify();
+    }
+
+    [Test]
+    public void SetPropertyDefinitions_IsReadOnly ()
+    {
+      _domainBaseTypeDefinition.SetupForReadOnlyUsage();
+      _domainBaseTypeDefinition.SetReadOnly();
+
+      Assert.That(
+          () => _domainBaseTypeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new PropertyDefinition[0], true)),
+          Throws.InstanceOf<NotSupportedException>()
+              .With.Message.EqualTo("Type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TypeDefinitionTest+IDomainBase' is read-only."));
+    }
+
+    [Test]
+    public void GetRelationEndPointDefinitions ()
+    {
+      var collection = new RelationEndPointDefinitionCollection();
+      _createRelationEndpointCollectionMock.Setup(_ => _()).Returns(collection);
+
+      var actualCollection = _domainBaseTypeDefinition.GetRelationEndPointDefinitions();
+
+      Assert.That(actualCollection, Is.SameAs(collection));
+    }
+
+    [Test]
+    public void GetRelationEndPointDefinitions_SecondCall_ReturnsNewCollection ()
+    {
+      _createRelationEndpointCollectionMock.Setup(_ => _()).Returns(() => new RelationEndPointDefinitionCollection());
+
+      var result1 = _domainBaseTypeDefinition.GetRelationEndPointDefinitions();
+      var result2 = _domainBaseTypeDefinition.GetRelationEndPointDefinitions();
+
+      Assert.That(result1, Is.Not.Null);
+      Assert.That(result1, Is.Not.SameAs(result2));
+    }
+
+    [Test]
+    public void GetRelationEndPointDefinitions_SecondCall_ReturnsCachedResult ()
+    {
+      _createRelationEndpointCollectionMock.Setup(_ => _()).Returns(() => new RelationEndPointDefinitionCollection());
+      _domainBaseTypeDefinition.SetupForReadOnlyUsage();
+      _domainBaseTypeDefinition.SetReadOnly();
+
+      var result1 = _domainBaseTypeDefinition.GetRelationEndPointDefinitions();
+      var result2 = _domainBaseTypeDefinition.GetRelationEndPointDefinitions();
+
+      Assert.That(result1, Is.Not.Null);
+      Assert.That(result1, Is.SameAs(result2));
+    }
+
+    [Test]
+    public void GetRelationEndPointDefinition ()
+    {
+      var endPoint = new VirtualObjectRelationEndPointDefinition(
+          _domainBaseTypeDefinition,
+          "Test",
+          false,
+          new Mock<IPropertyInformation>().Object);
+
+      var collection = new RelationEndPointDefinitionCollection(new[] { endPoint }, true);
+      var createRelationEndPointDefinitionCollectionMock = new Mock<Func<RelationEndPointDefinitionCollection>>();
+      createRelationEndPointDefinitionCollectionMock.Setup(_ => _()).Returns(collection);
+
+      _domainBaseTypeDefinition.CreateRelationEndPointDefinitionCollectionCallback = createRelationEndPointDefinitionCollectionMock.Object;
+
+      Assert.That(
+          _domainBaseTypeDefinition.GetRelationEndPointDefinition("Test"),
+          Is.SameAs(endPoint));
+    }
+
+    [Test]
+    public void GetRelationEndPointDefinition_EmptyRelationEndPointName_Throws ()
+    {
+      Assert.That(
+          () => _domainBaseTypeDefinition.GetRelationEndPointDefinition(string.Empty),
+          Throws.ArgumentException
+              .With.ArgumentExceptionMessageEqualTo("Parameter 'propertyName' cannot be empty.", "propertyName"));
+    }
+
+    [Test]
+    public void GetRelationEndPointDefinition_NonExistingRelationEndPoint_ReturnsNull ()
+    {
+      var collection = new RelationEndPointDefinitionCollection();
+      _createRelationEndpointCollectionMock.Setup(_ => _()).Returns(collection);
+
+      Assert.That(_domainBaseTypeDefinition.GetRelationEndPointDefinition("dummy"), Is.Null);
+    }
+
+    [Test]
+    public void GetMandatoryRelationEndPointDefinition_NonExistingRelationEndPoint_Throws ()
+    {
+      var collection = new RelationEndPointDefinitionCollection();
+      _createRelationEndpointCollectionMock.Setup(_ => _()).Returns(collection);
+
+      Assert.That(
+          () => _domainBaseTypeDefinition.GetMandatoryRelationEndPointDefinition("dummy"),
+          Throws.TypeOf<MappingException>()
+              .With.Message.EqualTo(
+                  "No relation found for type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TypeDefinitionTest+IDomainBase' and property 'dummy'."));
+    }
+
+    [Test]
+    public void SetRelationEndPointDefinitions ()
+    {
+      var endPoint = new VirtualObjectRelationEndPointDefinition(
+          _domainBaseTypeDefinition,
+          "Test",
+          false,
+          new Mock<IPropertyInformation>().Object);
+
+      _checkRelationEndPointDefinitionsMock.Setup(_ => _(new[] { endPoint }))
+          .Callback(
+              () => { Assert.That(() => _domainBaseTypeDefinition.MyRelationEndPointDefinitions, Throws.Exception); }
+          )
+          .Verifiable();
+
+      _domainBaseTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { endPoint }, false));
+
+      Assert.That(_domainBaseTypeDefinition.MyRelationEndPointDefinitions.Count, Is.EqualTo(1));
+      Assert.That(_domainBaseTypeDefinition.MyRelationEndPointDefinitions[0], Is.SameAs(endPoint));
+      Assert.That(_domainBaseTypeDefinition.MyRelationEndPointDefinitions.IsReadOnly, Is.True);
+
+      _checkRelationEndPointDefinitionsMock.Verify();
+    }
+
+    [Test]
+    public void SetRelationEndPointDefinitions_IsReadOnly ()
+    {
+      _domainBaseTypeDefinition.SetupForReadOnlyUsage();
+      _domainBaseTypeDefinition.SetReadOnly();
+      Assert.That(
+          () => _domainBaseTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(Array.Empty<RelationEndPointDefinition>(), true)),
+          Throws.InstanceOf<NotSupportedException>()
+              .With.Message.EqualTo("Type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TypeDefinitionTest+IDomainBase' is read-only."));
+    }
+
+    [Test]
+    public void SetReadOnly ()
+    {
+      Assert.That(_domainBaseTypeDefinition.IsReadOnly, Is.False);
+
+      _domainBaseTypeDefinition.SetupForReadOnlyUsage();
+      _domainBaseTypeDefinition.SetReadOnly();
+
+      Assert.That(_domainBaseTypeDefinition.IsReadOnly, Is.True);
+    }
+
+    [Test]
+    public void SetReadOnly_WithUnsetStorageEntity_Throws ()
+    {
+      _domainBaseTypeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
+      _domainBaseTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+
+      Assert.That(
+          () => _domainBaseTypeDefinition.SetReadOnly(),
+          Throws.InvalidOperationException
+              .With.Message.EqualTo("Cannot set the type definition read-only as the storage entity definition is not set."));
+    }
+
+    [Test]
+    public void SetReadOnly_WithUnsetPropertyDefinitions_Throws ()
+    {
+      _domainBaseTypeDefinition.SetStorageEntity(new FakeStorageEntityDefinition(new UnitTestStorageProviderStubDefinition("stub"), "stub"));
+      _domainBaseTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+
+      Assert.That(
+          () => _domainBaseTypeDefinition.SetReadOnly(),
+          Throws.InvalidOperationException
+              .With.Message.EqualTo("Cannot set the type definition read-only as the property definitions are not set."));
+    }
+
+    [Test]
+    public void SetReadOnly_WithUnsetRelationEndPointDefinitions_Throws ()
+    {
+      _domainBaseTypeDefinition.SetStorageEntity(new FakeStorageEntityDefinition(new UnitTestStorageProviderStubDefinition("stub"), "stub"));
+      _domainBaseTypeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
+
+      Assert.That(
+          () => _domainBaseTypeDefinition.SetReadOnly(),
+          Throws.InvalidOperationException
+              .With.Message.EqualTo("Cannot set the type definition read-only as the relation endpoint definitions are not set."));
+    }
+
+    [Test]
+    public void GetToString ()
+    {
+      Assert.That(
+          _domainBaseTypeDefinition.ToString(),
+          Is.EqualTo("TestableTypeDefinition: Remotion.Data.DomainObjects.UnitTests.Mapping.TypeDefinitionTest+IDomainBase"));
+    }
+
+    [Test]
+    public void Indexer ()
+    {
+      var propertyInformation = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(
+          _domainBaseTypeDefinition,
+          "Test");
+      _domainBaseTypeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyInformation }, true));
+
+      var actual = _domainBaseTypeDefinition["Test"];
+      Assert.That(actual, Is.EqualTo(propertyInformation));
+    }
+
+    [Test]
+    public void Indexer_EmptyParameterName_Throws ()
+    {
+      Assert.That(
+          () => _domainBaseTypeDefinition[""],
+          Throws.ArgumentException
+              .With.ArgumentExceptionMessageWithParameterNameEqualTo("propertyName"));
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWalkerTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWalkerTest.cs
new file mode 100644
index 0000000000..ea4f755853
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWalkerTest.cs
@@ -0,0 +1,95 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using System.Collections.Generic;
+using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping
+{
+  [TestFixture]
+  public class TypeDefinitionWalkerTest : TypeDefinitionWalkerTestBase
+  {
+    private class TestableTypeDefinitionWalker : TypeDefinitionWalker
+    {
+      public List<TypeDefinition> VisitedTypeDefinitions { get; } = new();
+
+      public TestableTypeDefinitionWalker (TypeDefinitionWalkerDirection direction)
+          : base(direction)
+      {
+      }
+
+      /// <inheritdoc />
+      public override void VisitClassDefinition (ClassDefinition classDefinition)
+      {
+        VisitedTypeDefinitions.Add(classDefinition);
+        base.VisitClassDefinition(classDefinition);
+      }
+
+      /// <inheritdoc />
+      public override void VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition)
+      {
+        VisitedTypeDefinitions.Add(interfaceDefinition);
+        base.VisitInterfaceDefinition(interfaceDefinition);
+      }
+    }
+
+    [Test]
+    public void VisitClassDefinition_WithChildrenDirection_IsCalledInCorrectOrder ()
+    {
+      var (domainBase, person, customer, organizationalUnit) = CreateClassTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker(TypeDefinitionWalkerDirection.Descendants);
+      walker.VisitClassDefinition(domainBase);
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new[] { domainBase, person, customer, organizationalUnit }));
+    }
+
+    [Test]
+    public void VisitClassDefinition_WithParentsDirection_IsCalledInCorrectOrder ()
+    {
+      var (domainBase, person, customer, _) = CreateClassTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker(TypeDefinitionWalkerDirection.Ascendants);
+      walker.VisitClassDefinition(customer);
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new[] { customer, person, domainBase }));
+    }
+
+    [Test]
+    public void VisitInterfaceDefinition_WithChildrenDirection_IsCalledInCorrectOrder ()
+    {
+      var (_, iPerson, person, iCustomer) = CreateInterfaceTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker(TypeDefinitionWalkerDirection.Descendants);
+      walker.VisitInterfaceDefinition(iPerson);
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new TypeDefinition[] { iPerson, person, iCustomer }));
+    }
+
+    [Test]
+    public void VisitInterfaceDefinition_WithParentsDirection_IsCalledInCorrectOrder ()
+    {
+      var (iDomainBase, iPerson, _, _) = CreateInterfaceTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker(TypeDefinitionWalkerDirection.Ascendants);
+      walker.VisitInterfaceDefinition(iPerson);
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new[] { iPerson, iDomainBase }));
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWalkerTestBase.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWalkerTestBase.cs
new file mode 100644
index 0000000000..610dfd7da2
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWalkerTestBase.cs
@@ -0,0 +1,55 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using Remotion.Data.DomainObjects.Mapping;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping
+{
+  public abstract class TypeDefinitionWalkerTestBase
+  {
+    protected static (ClassDefinition domainBase, ClassDefinition person, ClassDefinition customer, ClassDefinition organizationalUnit) CreateClassTestDomain ()
+    {
+      var domainBase = ClassDefinitionObjectMother.CreateClassDefinition("DomainBase");
+      var person = ClassDefinitionObjectMother.CreateClassDefinition("Person", baseClass: domainBase);
+      var customer = ClassDefinitionObjectMother.CreateClassDefinition("Customer", baseClass: person);
+      var organizationalUnit = ClassDefinitionObjectMother.CreateClassDefinition("OrganizationalUnit", baseClass: domainBase);
+      domainBase.SetDerivedClasses(new[] { person, organizationalUnit });
+      person.SetDerivedClasses(new[] { customer });
+      customer.SetDerivedClasses(Array.Empty<ClassDefinition>());
+      organizationalUnit.SetDerivedClasses(Array.Empty<ClassDefinition>());
+
+      return (domainBase, person, customer, organizationalUnit);
+    }
+
+    protected static (InterfaceDefinition iDomainBase, InterfaceDefinition iPerson, ClassDefinition person, InterfaceDefinition iCustomer) CreateInterfaceTestDomain ()
+    {
+      var iDomainBase = InterfaceDefinitionObjectMother.CreateInterfaceDefinition();
+      var iPerson = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(extendedInterfaces: new[] { iDomainBase });
+      var person = ClassDefinitionObjectMother.CreateClassDefinition(implementedInterfaces: new[] { iPerson });
+      var iCustomer = InterfaceDefinitionObjectMother.CreateInterfaceDefinition(extendedInterfaces: new[] { iPerson });
+      iDomainBase.SetImplementingClasses(Array.Empty<ClassDefinition>());
+      iDomainBase.SetExtendingInterfaces(new []{iPerson});
+      iPerson.SetImplementingClasses(new []{person});
+      iPerson.SetExtendingInterfaces(new []{iCustomer});
+      person.SetDerivedClasses(Array.Empty<ClassDefinition>());
+      iCustomer.SetImplementingClasses(Array.Empty<ClassDefinition>());
+      iCustomer.SetExtendingInterfaces(Array.Empty<InterfaceDefinition>());
+
+      return (iDomainBase, iPerson, person, iCustomer);
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWalkerWithResultTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWalkerWithResultTest.cs
new file mode 100644
index 0000000000..deb2bebfad
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWalkerWithResultTest.cs
@@ -0,0 +1,157 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using System.Collections.Generic;
+using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping
+{
+  public class TypeDefinitionWalkerWithResultTest : TypeDefinitionWalkerTestBase
+  {
+    private class TestableTypeDefinitionWalker<T> : TypeDefinitionWalker<T>
+        where T : class
+    {
+      public Func<ClassDefinition, T> ClassDefinitionHandler { get; set; } = _ => null;
+
+      public Func<InterfaceDefinition, T> InterfaceDefinitionHandler { get; set; } = _ => null;
+
+      public List<TypeDefinition> VisitedTypeDefinitions { get; } = new();
+
+      public TestableTypeDefinitionWalker (TypeDefinitionWalkerDirection direction, Predicate<T> match)
+          : base(direction, match)
+      {
+      }
+
+      /// <inheritdoc />
+      public override T VisitClassDefinition (ClassDefinition classDefinition)
+      {
+        VisitedTypeDefinitions.Add(classDefinition);
+
+        var result = ClassDefinitionHandler(classDefinition);
+        if (Match(result))
+          return result;
+
+        return base.VisitClassDefinition(classDefinition);
+      }
+
+      /// <inheritdoc />
+      public override T VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition)
+      {
+        VisitedTypeDefinitions.Add(interfaceDefinition);
+
+        var result = InterfaceDefinitionHandler(interfaceDefinition);
+        if (Match(result))
+          return result;
+
+        return base.VisitInterfaceDefinition(interfaceDefinition);
+      }
+    }
+
+    [Test]
+    public void VisitClassDefinition_WithChildrenDirection_IsCalledInCorrectOrder ()
+    {
+      var (domainBase, person, customer, organizationalUnit) = TypeDefinitionWalkerTest.CreateClassTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker<string>(TypeDefinitionWalkerDirection.Descendants, value => value != null);
+      Assert.That(walker.VisitClassDefinition(domainBase), Is.Null);
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new[] { domainBase, person, customer, organizationalUnit }));
+    }
+
+    [Test]
+    public void VisitClassDefinition_WithChildrenDirection_AbortsTraversalOnNonNullValue ()
+    {
+      var (domainBase, person, customer, _) = TypeDefinitionWalkerTest.CreateClassTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker<string>(TypeDefinitionWalkerDirection.Descendants, value => value != null);
+      walker.ClassDefinitionHandler = classDefinition => classDefinition == customer ? "finish" : null;
+      Assert.That(walker.VisitClassDefinition(domainBase), Is.EqualTo("finish"));
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new[] { domainBase, person, customer }));
+    }
+
+    [Test]
+    public void VisitClassDefinition_WithParentsDirection_IsCalledInCorrectOrder ()
+    {
+      var (domainBase, person, customer, _) = TypeDefinitionWalkerTest.CreateClassTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker<string>(TypeDefinitionWalkerDirection.Ascendants, value => value != null);
+      Assert.That(walker.VisitClassDefinition(customer), Is.Null);
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new[] { customer, person, domainBase }));
+    }
+
+    [Test]
+    public void VisitClassDefinition_WithParentsDirection_AbortsTraversalOnNonNullValue ()
+    {
+      var (_, person, customer, _) = TypeDefinitionWalkerTest.CreateClassTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker<string>(TypeDefinitionWalkerDirection.Ascendants, value => value != null);
+      walker.ClassDefinitionHandler = classDefinition => classDefinition == person ? "finish" : null;
+      Assert.That(walker.VisitClassDefinition(customer), Is.EqualTo("finish"));
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new[] { customer, person }));
+    }
+
+    [Test]
+    public void VisitInterfaceDefinition_WithChildrenDirection_IsCalledInCorrectOrder ()
+    {
+      var (_, iPerson, person, iCustomer) = TypeDefinitionWalkerTest.CreateInterfaceTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker<string>(TypeDefinitionWalkerDirection.Descendants, value => value != null);
+      Assert.That(walker.VisitInterfaceDefinition(iPerson), Is.Null);
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new TypeDefinition[] { iPerson, person, iCustomer }));
+    }
+
+    [Test]
+    public void VisitInterfaceDefinition_WithChildrenDirection_AbortsTraversalOnNonNullValue ()
+    {
+      var (iDomainBase, iPerson, _, _) = TypeDefinitionWalkerTest.CreateInterfaceTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker<string>(TypeDefinitionWalkerDirection.Descendants, value => value != null);
+      walker.InterfaceDefinitionHandler = interfaceDefinition => interfaceDefinition == iPerson ? "finish" : null;
+      Assert.That(walker.VisitInterfaceDefinition(iDomainBase), Is.EqualTo("finish"));
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new[] { iDomainBase, iPerson }));
+    }
+
+    [Test]
+    public void VisitInterfaceDefinition_WithParentsDirection_IsCalledInCorrectOrder ()
+    {
+      var (iDomainBase, iPerson, _, iCustomer) = TypeDefinitionWalkerTest.CreateInterfaceTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker<string>(TypeDefinitionWalkerDirection.Ascendants, value => value != null);
+      Assert.That(walker.VisitInterfaceDefinition(iCustomer), Is.Null);
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new[] { iCustomer, iPerson, iDomainBase }));
+    }
+
+    [Test]
+    public void VisitInterfaceDefinition_WithParentsDirection_AbortsTraversalOnNonNullValue ()
+    {
+      var (_, iPerson, _, iCustomer) = TypeDefinitionWalkerTest.CreateInterfaceTestDomain();
+
+      var walker = new TestableTypeDefinitionWalker<string>(TypeDefinitionWalkerDirection.Ascendants, value => value != null);
+      walker.InterfaceDefinitionHandler = interfaceDefinition => interfaceDefinition == iPerson ? "finish" : null;
+      Assert.That(walker.VisitInterfaceDefinition(iCustomer), Is.EqualTo("finish"));
+
+      Assert.That(walker.VisitedTypeDefinitions, Is.EqualTo(new[] { iCustomer, iPerson }));
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionWithNullEndPointTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWithNullEndPointTest.cs
similarity index 71%
rename from Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionWithNullEndPointTest.cs
rename to Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWithNullEndPointTest.cs
index 659b6b6878..03e18828f2 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/ClassDefinitionWithNullEndPointTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeDefinitionWithNullEndPointTest.cs
@@ -22,7 +22,7 @@
 namespace Remotion.Data.DomainObjects.UnitTests.Mapping
 {
   [TestFixture]
-  public class ClassDefinitionWithNullEndPointTest : MappingReflectionTestBase
+  public class TypeDefinitionWithNullEndPointTest : MappingReflectionTestBase
   {
     // types
 
@@ -30,9 +30,9 @@ public class ClassDefinitionWithNullEndPointTest : MappingReflectionTestBase
 
     // member fields
 
-    private ClassDefinition _clientClass;
+    private TypeDefinition _clientTypeDefinition;
     private AnonymousRelationEndPointDefinition _clientEndPoint;
-    private ClassDefinition _locationClass;
+    private TypeDefinition _locationTypeDefinition;
     private RelationEndPointDefinition _locationEndPoint;
 
     // methods and properties
@@ -41,8 +41,8 @@ public override void SetUp ()
     {
       base.SetUp();
 
-      _clientClass = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Client)];
-      _locationClass = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Location)];
+      _clientTypeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Client)];
+      _locationTypeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Location)];
 
       RelationDefinition relation = FakeMappingConfiguration.Current.RelationDefinitions[
           "Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Location:Remotion.Data.DomainObjects.UnitTests.Mapping."
@@ -54,15 +54,15 @@ public override void SetUp ()
     [Test]
     public void GetRelationEndPointDefinitions ()
     {
-      Assert.That(_locationClass.GetRelationEndPointDefinitions(), Has.Member(_locationEndPoint));
-      Assert.That(_clientClass.GetRelationEndPointDefinitions(), Has.No.Member(_clientEndPoint));
+      Assert.That(_locationTypeDefinition.GetRelationEndPointDefinitions(), Has.Member(_locationEndPoint));
+      Assert.That(_clientTypeDefinition.GetRelationEndPointDefinitions(), Has.No.Member(_clientEndPoint));
     }
 
     [Test]
     public void GetMyRelationEndPointDefinitions ()
     {
-      Assert.That(_locationClass.MyRelationEndPointDefinitions, Has.Member(_locationEndPoint));
-      Assert.That(_clientClass.MyRelationEndPointDefinitions, Has.No.Member(_clientEndPoint));
+      Assert.That(_locationTypeDefinition.MyRelationEndPointDefinitions, Has.Member(_locationEndPoint));
+      Assert.That(_clientTypeDefinition.MyRelationEndPointDefinitions, Has.No.Member(_clientEndPoint));
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeNotFoundClassDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeNotFoundTypeDefinitionTest.cs
similarity index 66%
rename from Remotion/Data/DomainObjects.UnitTests/Mapping/TypeNotFoundClassDefinitionTest.cs
rename to Remotion/Data/DomainObjects.UnitTests/Mapping/TypeNotFoundTypeDefinitionTest.cs
index bb308d04c0..e9b418b3ec 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeNotFoundClassDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/TypeNotFoundTypeDefinitionTest.cs
@@ -24,28 +24,26 @@
 namespace Remotion.Data.DomainObjects.UnitTests.Mapping
 {
   [TestFixture]
-  public class TypeNotFoundClassDefinitionTest
+  public class TypeNotFoundTypeDefinitionTest
   {
-    private ClassDefinitionForUnresolvedRelationPropertyType _classDefinition;
-    private Type _classType;
+    private TypeDefinitionForUnresolvedRelationPropertyType _typeDefinition;
+    private Type _type;
     private Mock<IPropertyInformation> _relationProperty;
 
     [SetUp]
     public void SetUp ()
     {
-      _classType = typeof(ClassNotInMapping);
+      _type = typeof(ClassNotInMapping);
       _relationProperty = new Mock<IPropertyInformation>();
-      _classDefinition = new ClassDefinitionForUnresolvedRelationPropertyType("Test", _classType, _relationProperty.Object);
+      _typeDefinition = new TypeDefinitionForUnresolvedRelationPropertyType(_type, _relationProperty.Object);
     }
 
     [Test]
     public void Initialization ()
     {
-      Assert.That(_classDefinition.ClassType, Is.SameAs(_classType));
-      Assert.That(_classDefinition.BaseClass, Is.Null);
-      Assert.That(_classDefinition.IsClassTypeResolved, Is.False);
-      Assert.That(_classDefinition.IsAbstract, Is.False);
-      Assert.That(_classDefinition.RelationProperty, Is.SameAs(_relationProperty.Object));
+      Assert.That(_typeDefinition.Type, Is.SameAs(_type));
+      Assert.That(_typeDefinition.IsTypeResolved, Is.False);
+      Assert.That(_typeDefinition.RelationProperty, Is.SameAs(_relationProperty.Object));
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/ClassDefinitionValidatorTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/ClassDefinitionValidatorTest.cs
deleted file mode 100644
index b7be5a1567..0000000000
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/ClassDefinitionValidatorTest.cs
+++ /dev/null
@@ -1,136 +0,0 @@
-// This file is part of the re-motion Core Framework (www.re-motion.org)
-// Copyright (c) rubicon IT GmbH, www.rubicon.eu
-// 
-// The re-motion Core Framework is free software; you can redistribute it 
-// and/or modify it under the terms of the GNU Lesser General Public License 
-// as published by the Free Software Foundation; either version 2.1 of the 
-// License, or (at your option) any later version.
-// 
-// re-motion is distributed in the hope that it will be useful, 
-// but WITHOUT ANY WARRANTY; without even the implied warranty of 
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
-// GNU Lesser General Public License for more details.
-// 
-// You should have received a copy of the GNU Lesser General Public License
-// along with re-motion; if not, see http://www.gnu.org/licenses.
-// 
-using System;
-using System.Linq;
-using Moq;
-using NUnit.Framework;
-using Remotion.Data.DomainObjects.Mapping;
-using Remotion.Data.DomainObjects.Mapping.Validation;
-using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation;
-
-namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation
-{
-  [TestFixture]
-  public class ClassDefinitionValidatorTest
-  {
-    private ClassDefinition _classDefinition1;
-    private ClassDefinition _classDefinition2;
-    private ClassDefinition _classDefinition3;
-    private MappingValidationResult _fakeValidMappingValidationResult;
-    private MappingValidationResult _fakeInvalidMappingValidationResult;
-    private Mock<IClassDefinitionValidationRule> _validationRuleMock1;
-    private Mock<IClassDefinitionValidationRule> _validationRuleMock2;
-    private Mock<IClassDefinitionValidationRule> _validationRuleMock3;
-
-    [SetUp]
-    public void SetUp ()
-    {
-      _classDefinition1 = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
-      _classDefinition2 = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
-      _classDefinition3 = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
-
-      _validationRuleMock1 = new Mock<IClassDefinitionValidationRule>(MockBehavior.Strict);
-      _validationRuleMock2 = new Mock<IClassDefinitionValidationRule>(MockBehavior.Strict);
-      _validationRuleMock3 = new Mock<IClassDefinitionValidationRule>(MockBehavior.Strict);
-
-      _fakeValidMappingValidationResult = MappingValidationResult.CreateValidResult();
-      _fakeInvalidMappingValidationResult = MappingValidationResult.CreateInvalidResult("Test");
-    }
-
-    [Test]
-    public void ValidateWithOneRuleAndClassDefinition_ValidResult ()
-    {
-      var validator = new ClassDefinitionValidator(_validationRuleMock1.Object);
-
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(_fakeValidMappingValidationResult).Verifiable();
-
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1 }).ToArray();
-
-      _validationRuleMock1.Verify();
-      Assert.That(validator.ValidationRules.Count, Is.EqualTo(1));
-      Assert.That(mappingValidationResults.Length, Is.EqualTo(0));
-    }
-
-    [Test]
-    public void ValidateWithOneRuleAndClassDefinition_InvalidResult ()
-    {
-      var validator = new ClassDefinitionValidator(_validationRuleMock1.Object);
-
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
-
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1 }).ToArray();
-
-      _validationRuleMock1.Verify();
-      Assert.That(validator.ValidationRules.Count, Is.EqualTo(1));
-      Assert.That(mappingValidationResults.Length, Is.EqualTo(1));
-      Assert.That(mappingValidationResults[0], Is.SameAs(_fakeInvalidMappingValidationResult));
-    }
-
-    [Test]
-    public void ValidateWithSeveralRulesAndClassDefinitions_ValidResult ()
-    {
-      var validator = new ClassDefinitionValidator(_validationRuleMock1.Object, _validationRuleMock2.Object, _validationRuleMock3.Object);
-
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(_fakeValidMappingValidationResult).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition2)).Returns(_fakeValidMappingValidationResult).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition3)).Returns(_fakeValidMappingValidationResult).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition1)).Returns(_fakeValidMappingValidationResult).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition2)).Returns(_fakeValidMappingValidationResult).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition3)).Returns(_fakeValidMappingValidationResult).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition1)).Returns(_fakeValidMappingValidationResult).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition2)).Returns(_fakeValidMappingValidationResult).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition3)).Returns(_fakeValidMappingValidationResult).Verifiable();
-
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1, _classDefinition2, _classDefinition3 }).ToArray();
-
-      _validationRuleMock1.Verify();
-      Assert.That(validator.ValidationRules.Count, Is.EqualTo(3));
-      Assert.That(mappingValidationResults.Length, Is.EqualTo(0));
-    }
-
-    [Test]
-    public void ValidateWithSeveralRulesAndClassDefinitions_InvalidResult ()
-    {
-      var validator = new ClassDefinitionValidator(_validationRuleMock1.Object, _validationRuleMock2.Object, _validationRuleMock3.Object);
-
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition2)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition3)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition1)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition2)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition3)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition1)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition2)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition3)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
-
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1, _classDefinition2, _classDefinition3 }).ToArray();
-
-      _validationRuleMock1.Verify();
-      Assert.That(validator.ValidationRules.Count, Is.EqualTo(3));
-      Assert.That(mappingValidationResults.Length, Is.EqualTo(9));
-      Assert.That(mappingValidationResults[0], Is.SameAs(_fakeInvalidMappingValidationResult));
-      Assert.That(mappingValidationResults[1], Is.SameAs(_fakeInvalidMappingValidationResult));
-      Assert.That(mappingValidationResults[2], Is.SameAs(_fakeInvalidMappingValidationResult));
-      Assert.That(mappingValidationResults[3], Is.SameAs(_fakeInvalidMappingValidationResult));
-      Assert.That(mappingValidationResults[4], Is.SameAs(_fakeInvalidMappingValidationResult));
-      Assert.That(mappingValidationResults[5], Is.SameAs(_fakeInvalidMappingValidationResult));
-      Assert.That(mappingValidationResults[6], Is.SameAs(_fakeInvalidMappingValidationResult));
-      Assert.That(mappingValidationResults[7], Is.SameAs(_fakeInvalidMappingValidationResult));
-      Assert.That(mappingValidationResults[8], Is.SameAs(_fakeInvalidMappingValidationResult));
-    }
-  }
-}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/ClassDefinitionWithUnresolvedClassType.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/ClassDefinitionWithUnresolvedType.cs
similarity index 75%
rename from Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/ClassDefinitionWithUnresolvedClassType.cs
rename to Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/ClassDefinitionWithUnresolvedType.cs
index 8cd69a61bf..819e0a4d52 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/ClassDefinitionWithUnresolvedClassType.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/ClassDefinitionWithUnresolvedType.cs
@@ -15,25 +15,27 @@
 // along with re-motion; if not, see http://www.gnu.org/licenses.
 // 
 using System;
+using System.Collections.Generic;
 using Remotion.Data.DomainObjects.Infrastructure;
 using Remotion.Data.DomainObjects.Mapping;
 
 namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation
 {
-  public class ClassDefinitionWithUnresolvedClassType : ClassDefinition
+  public class ClassDefinitionWithUnresolvedType : ClassDefinition
   {
-    public ClassDefinitionWithUnresolvedClassType (
+    public ClassDefinitionWithUnresolvedType (
         string id,
         Type classType,
         bool isAbstract,
         ClassDefinition baseClass,
+        IEnumerable<InterfaceDefinition> implementedInterfaces,
         IPersistentMixinFinder persistentMixinFinder,
         IDomainObjectCreator instanceCreator)
-        : base(id, classType, isAbstract, baseClass, null, DefaultStorageClass.Persistent, persistentMixinFinder, instanceCreator)
+        : base(id, classType, isAbstract, baseClass, implementedInterfaces, null, DefaultStorageClass.Persistent, persistentMixinFinder, instanceCreator)
     {
     }
 
-    public override bool IsClassTypeResolved
+    public override bool IsTypeResolved
     {
       get { return false; }
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/IntegrationTests/NotSupportedPropertyTypesIntegrationTests.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/IntegrationTests/NotSupportedPropertyTypesIntegrationTests.cs
index d045d87908..85940df704 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/IntegrationTests/NotSupportedPropertyTypesIntegrationTests.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/IntegrationTests/NotSupportedPropertyTypesIntegrationTests.cs
@@ -47,7 +47,7 @@ public void PropertyTypeOfDomainObjectWithoutStorageClassNone ()
           Throws.InstanceOf<MappingException>()
               .With.Message.EqualTo(
                   "The relation property 'InvalidProperty' has return type 'DomainObject', which is not a part of the mapping. Relation properties must not point "
-                  +"to classes above the inheritance root.\r\n\r\n"
+                  +"to types above the inheritance root.\r\n\r\n"
                   +"Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Integration.NotSupportedPropertyTypes."
                   +"PropertyTypeOfDomainObjectWithoutStorageClassNone.ClassWithInvalidPropertyType\r\n"
                   + "Property: InvalidProperty"));
@@ -62,7 +62,7 @@ public void PropertyTypeToDomainObjectAboveTheInheritanceRoot ()
           Throws.InstanceOf<MappingException>()
               .With.Message.EqualTo(
                   "The relation property 'InvalidProperty' has return type 'ClassAboveInheritanceRoot', which is not a part of the mapping. Relation properties "
-                  +"must not point to classes above the inheritance root.\r\n\r\n"
+                  +"must not point to types above the inheritance root.\r\n\r\n"
                   +"Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Integration.NotSupportedPropertyTypes."
                   +"PropertyTypeToDomainObjectAboveTheInheritanceRoot.InheritanceRootClass\r\n"
                   + "Property: InvalidProperty"));
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/IntegrationTests/NotSupportedRelationsIntegrationTests.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/IntegrationTests/NotSupportedRelationsIntegrationTests.cs
index 3370795041..fa4945b580 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/IntegrationTests/NotSupportedRelationsIntegrationTests.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/IntegrationTests/NotSupportedRelationsIntegrationTests.cs
@@ -125,7 +125,7 @@ public void OneToOne_WithSortExpression ()
           () => ValidateMapping("NotSupportedRelations.OneToOne_WithSortExpression"),
           Throws.InstanceOf<MappingException>()
               .With.Message.EqualTo(
-                  "Property 'RelationProperty1' of class 'InvalidRelationClass1' must not specify a SortExpression, because cardinality is equal to 'one'.\r\n\r\n"
+                  "Property 'RelationProperty1' of type 'InvalidRelationClass1' must not specify a SortExpression, because cardinality is equal to 'one'.\r\n\r\n"
                   + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Integration.NotSupportedRelations."
                   + "OneToOne_WithSortExpression.InvalidRelationClass1\r\nProperty: RelationProperty1"));
     }
@@ -184,7 +184,7 @@ public void Bidirectional_RelationEndPointDefinitionsDoNotMatch ()
                   + "Bidirectional_RelationEndPointDefinitionsDoNotMatch.InvalidRelationClass2\r\n"
                   + "Property: RelationProperty1\r\n"
                   + "----------\r\n"
-                  + "Property 'RelationProperty2' on class 'InvalidRelationClass1' could not be found.\r\n\r\n"
+                  + "Property 'RelationProperty2' on type 'InvalidRelationClass1' could not be found.\r\n\r\n"
                   + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Integration.NotSupportedRelations."
                   + "Bidirectional_RelationEndPointDefinitionsDoNotMatch.InvalidRelationClass1"));
     }
@@ -229,12 +229,12 @@ public void RelationPropertyTypeNotInMapping ()
                   + "RelationPropertyTypeNotInMapping.InvalidRelationClass1\r\n"
                   + "Property: RelationProperty\r\n"
                   + "----------\r\n"
-                  + "Property 'RelationProperty' on class 'ClassNotInMapping' could not be found.\r\n\r\n"
+                  + "Property 'RelationProperty' on type 'ClassNotInMapping' could not be found.\r\n\r\n"
                   + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Integration.NotSupportedRelations."
                   + "RelationPropertyTypeNotInMapping.ClassNotInMapping\r\n"
                   + "----------\r\n"
                   + "The relation property 'RelationProperty' has return type 'ClassNotInMapping', which is not a part of the mapping. Relation properties must "
-                  + "not point to classes above the inheritance root.\r\n\r\n"
+                  + "not point to types above the inheritance root.\r\n\r\n"
                   + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Integration.NotSupportedRelations."
                   + "RelationPropertyTypeNotInMapping.InvalidRelationClass1\r\n"
                   + "Property: RelationProperty"));
@@ -279,7 +279,7 @@ public void Bidirectional_ReferencingDomainObjectType ()
           Throws.InstanceOf<MappingException>()
               .With.Message.Contains(
                   "The relation property 'BidirectionalRelationProperty' has return type 'DomainObject', which is not a part of the mapping. "
-                  + "Relation properties must not point to classes above the inheritance root.\r\n\r\n"
+                  + "Relation properties must not point to types above the inheritance root.\r\n\r\n"
                   + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Integration.NotSupportedRelations.Bidirectional_ReferencingDomainObjectType.ClassReferencingDomainObjectType\r\n"
                   + "Property: BidirectionalRelationProperty"));
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForClassIDIsValidValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForClassIDIsValidValidationRuleTest.cs
index 716b9340a7..eb2ad2a9a2 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForClassIDIsValidValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForClassIDIsValidValidationRuleTest.cs
@@ -17,7 +17,9 @@
 using System;
 using NUnit.Framework;
 using Remotion.Data.DomainObjects.Infrastructure.ObjectIDStringSerialization;
+using Remotion.Data.DomainObjects.Mapping;
 using Remotion.Data.DomainObjects.Mapping.Validation.Logical;
+using Remotion.Reflection;
 
 namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Logical
 {
@@ -41,9 +43,9 @@ public void SetUp ()
     [TestCase("a1")]
     public void ValidClassID (string classID)
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(id: classID);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(id: classID);
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -56,9 +58,9 @@ public void ValidClassID (string classID)
     [TestCase("a+a")]
     public void InvalidClassID (string classID)
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(id: classID);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(id: classID);
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       var expectedMessage =
           string.Format(
@@ -72,9 +74,9 @@ public void InvalidClassID (string classID)
     public void IntegrationTestForObjectIDStringSerializer ()
     {
       var classID = "Class" + ObjectIDStringSerializer.Delimiter + "End";
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(id: classID);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(id: classID);
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       var expectedMessage =
           string.Format(
@@ -83,5 +85,15 @@ public void IntegrationTestForObjectIDStringSerializer ()
               classID);
       AssertMappingValidationResult(validationResult, false, expectedMessage);
     }
+
+    [Test]
+    public void IgnoresArgumentsOfTypeOtherThanClassDefinition ()
+    {
+      var typeDefinition = new TypeDefinitionForUnresolvedRelationPropertyType(typeof(string), new NullPropertyInformation());
+
+      var validationResult = _validationRule.Validate(typeDefinition);
+
+      AssertMappingValidationResult(validationResult, true, null);
+    }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForInvalidRelationEndPointsValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForInvalidRelationEndPointsValidationRuleTest.cs
index 3a4484bf05..1fbeff4aa2 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForInvalidRelationEndPointsValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForInvalidRelationEndPointsValidationRuleTest.cs
@@ -26,19 +26,19 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Logical
   public class CheckForInvalidRelationEndPointsValidationRuleTest : ValidationRuleTestBase
   {
     private CheckForInvalidRelationEndPointsValidationRule _validationRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     [SetUp]
     public void SetUp ()
     {
       _validationRule = new CheckForInvalidRelationEndPointsValidationRule();
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedValidationDomainObjectClass));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedValidationDomainObjectClass));
     }
 
     [Test]
     public void RelationDefinitionWithValidRelationEndPointDefinition ()
     {
-      var endPoint = new AnonymousRelationEndPointDefinition(_classDefinition);
+      var endPoint = new AnonymousRelationEndPointDefinition(_typeDefinition);
       var relationDefinition = new RelationDefinition("Test", endPoint, endPoint);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -49,12 +49,12 @@ public void RelationDefinitionWithValidRelationEndPointDefinition ()
     [Test]
     public void RelationDefinitionWithPropertyNotFoundRelationEndPointDefinition ()
     {
-      var endPoint = new PropertyNotFoundRelationEndPointDefinition(_classDefinition, "TestProperty", typeof(object));
+      var endPoint = new PropertyNotFoundRelationEndPointDefinition(_typeDefinition, "TestProperty", typeof(object));
       var relationDefinition = new RelationDefinition("Test", endPoint, endPoint);
 
       var validationResult = _validationRule.Validate(relationDefinition);
 
-      var expectedMessage = "Property 'TestProperty' on class 'DerivedValidationDomainObjectClass' could not be found.\r\n\r\n"
+      var expectedMessage = "Property 'TestProperty' on type 'DerivedValidationDomainObjectClass' could not be found.\r\n\r\n"
         +"Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.DerivedValidationDomainObjectClass";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
     }
@@ -62,12 +62,12 @@ public void RelationDefinitionWithPropertyNotFoundRelationEndPointDefinition ()
     [Test]
     public void RelationDefinitionWithTypeNotObjectIDRelationEndPointDefinition ()
     {
-      var endPoint = new TypeNotObjectIDRelationEndPointDefinition(_classDefinition, "TestProperty", typeof(string));
+      var endPoint = new TypeNotObjectIDRelationEndPointDefinition(_typeDefinition, "TestProperty", typeof(string));
       var relationDefinition = new RelationDefinition("Test", endPoint, endPoint);
 
       var validationResult = _validationRule.Validate(relationDefinition);
 
-      var expectedMessage = "Relation property 'TestProperty' on class 'DerivedValidationDomainObjectClass' is of type 'String', but non-virtual "
+      var expectedMessage = "Relation property 'TestProperty' on type 'DerivedValidationDomainObjectClass' is of type 'String', but non-virtual "
         +"relation properties must be of type 'ObjectID'.\r\n\r\n"
         +"Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.DerivedValidationDomainObjectClass";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
@@ -76,12 +76,12 @@ public void RelationDefinitionWithTypeNotObjectIDRelationEndPointDefinition ()
     [Test]
     public void RelationDefinitionWithTypeNotCompatibleWithVirtualRelationEndPointDefinition ()
     {
-      var endPoint = new TypeNotCompatibleWithVirtualRelationEndPointDefinition(_classDefinition, "TestProperty", typeof(string));
+      var endPoint = new TypeNotCompatibleWithVirtualRelationEndPointDefinition(_typeDefinition, "TestProperty", typeof(string));
       var relationDefinition = new RelationDefinition("Test", endPoint, endPoint);
 
       var validationResult = _validationRule.Validate(relationDefinition);
 
-      var expectedMessage = "Relation property 'TestProperty' on class 'DerivedValidationDomainObjectClass' is of type 'String', but virtual "
+      var expectedMessage = "Relation property 'TestProperty' on type 'DerivedValidationDomainObjectClass' is of type 'String', but virtual "
                             +"relation properties must be of type 'DomainObject', 'ObjectList`1', or 'IObjectList`1'.\r\n\r\n"
                             +"Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.DerivedValidationDomainObjectClass";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForTypeNotFoundClassDefinitionValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForTypeNotFoundTypeDefinitionValidationRuleTest.cs
similarity index 79%
rename from Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForTypeNotFoundClassDefinitionValidationRuleTest.cs
rename to Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForTypeNotFoundTypeDefinitionValidationRuleTest.cs
index 07b6906d87..bf2bcca6bd 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForTypeNotFoundClassDefinitionValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/CheckForTypeNotFoundTypeDefinitionValidationRuleTest.cs
@@ -24,21 +24,21 @@
 namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Logical
 {
   [TestFixture]
-  public class CheckForTypeNotFoundClassDefinitionValidationRuleTest : ValidationRuleTestBase
+  public class CheckForTypeNotFoundTypeDefinitionValidationRuleTest : ValidationRuleTestBase
   {
-    private CheckForTypeNotFoundClassDefinitionValidationRule _validationRule;
+    private CheckForTypeNotFoundTypeDefinitionValidationRule _validationRule;
 
     [SetUp]
     public void SetUp ()
     {
-      _validationRule = new CheckForTypeNotFoundClassDefinitionValidationRule();
+      _validationRule = new CheckForTypeNotFoundTypeDefinitionValidationRule();
     }
 
     [Test]
     public void RelationDefinitionWithNoTypeNotFoundClassDefinition ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedValidationDomainObjectClass));
-      var endPoint = new AnonymousRelationEndPointDefinition(classDefinition);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedValidationDomainObjectClass));
+      var endPoint = new AnonymousRelationEndPointDefinition(typeDefinition);
       var relationDefinition = new RelationDefinition("ID", endPoint, endPoint);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -49,8 +49,7 @@ public void RelationDefinitionWithNoTypeNotFoundClassDefinition ()
     [Test]
     public void RelationDefinitionWithTypeNotFoundClassDefinition ()
     {
-      var classDefinition = new ClassDefinitionForUnresolvedRelationPropertyType(
-          "Test",
+      var classDefinition = new TypeDefinitionForUnresolvedRelationPropertyType(
           typeof(ClassOutOfInheritanceHierarchy),
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("Property")));
       var endPoint = new VirtualObjectRelationEndPointDefinition(
@@ -64,7 +63,7 @@ public void RelationDefinitionWithTypeNotFoundClassDefinition ()
 
       var expectedMessage =
           "The relation property 'Property' has return type 'String', which is not a part of the mapping. "
-          + "Relation properties must not point to classes above the inheritance root.\r\n\r\n"
+          + "Relation properties must not point to types above the inheritance root.\r\n\r\n"
           + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.DerivedValidationDomainObjectClass\r\n"
           + "Property: Property";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/MandatoryExtensibleEnumTypeHasValuesDefinedValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/MandatoryExtensibleEnumTypeHasValuesDefinedValidationRuleTest.cs
index 0f3c232843..c02ab4e455 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/MandatoryExtensibleEnumTypeHasValuesDefinedValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/MandatoryExtensibleEnumTypeHasValuesDefinedValidationRuleTest.cs
@@ -10,21 +10,21 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Logical
   public class MandatoryExtensibleEnumTypeHasValuesDefinedValidationRuleTest : ValidationRuleTestBase
   {
     private MandatoryExtensibleEnumTypeHasValuesDefinedValidationRule _validationRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     [SetUp]
     public void SetUp ()
     {
       _validationRule = new MandatoryExtensibleEnumTypeHasValuesDefinedValidationRule();
 
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(EnumTypeValidationDomainObjectClass));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixinsAndDefaultProperties(typeof(EnumTypeValidationDomainObjectClass));
     }
 
     [Test]
     public void MandatoryPropertyWithOtherType_SupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(EnumTypeValidationDomainObjectClass).GetProperty("PropertyWithMandatoryOtherType")),
           "PropertyWithMandatoryOtherType",
           false,
@@ -33,10 +33,10 @@ public void MandatoryPropertyWithOtherType_SupportedType ()
           StorageClass.Persistent,
           default(float));
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithMandatoryOtherType"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -45,7 +45,7 @@ public void MandatoryPropertyWithOtherType_SupportedType ()
     public void MandatoryExtensibleEnumWithValuesProperty_SupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(EnumTypeValidationDomainObjectClass).GetProperty("PropertyWithMandatoryExtensibleEnumTypeWithValues")),
           "PropertyWithMandatoryExtensibleEnumTypeWithValues",
           false,
@@ -54,10 +54,10 @@ public void MandatoryExtensibleEnumWithValuesProperty_SupportedType ()
           StorageClass.Persistent,
           null);
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithMandatoryExtensibleEnumTypeWithValues"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -66,7 +66,7 @@ public void MandatoryExtensibleEnumWithValuesProperty_SupportedType ()
     public void NullableExtensibleEnumWithValuesProperty_SupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(EnumTypeValidationDomainObjectClass).GetProperty("PropertyWithNullableExtensibleEnumTypeWithValues")),
           "PropertyWithNullableExtensibleEnumTypeWithValues",
           false,
@@ -75,10 +75,10 @@ public void NullableExtensibleEnumWithValuesProperty_SupportedType ()
           StorageClass.Persistent,
           null);
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithNullableExtensibleEnumTypeWithValues"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -87,7 +87,7 @@ public void NullableExtensibleEnumWithValuesProperty_SupportedType ()
     public void MandatoryExtensibleEnumWithoutValuesProperty_UnsupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(EnumTypeValidationDomainObjectClass).GetProperty("PropertyWithMandatoryExtensibleEnumTypeWithoutValues")),
           "PropertyWithMandatoryExtensibleEnumTypeWithoutValues",
           false,
@@ -96,10 +96,10 @@ public void MandatoryExtensibleEnumWithoutValuesProperty_UnsupportedType ()
           StorageClass.Persistent,
           null);
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithMandatoryExtensibleEnumTypeWithoutValues"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       var expectedMessage =
           "Extensible enum type 'ExtensibleEnumTypeWithoutValues' cannot be used for property 'PropertyWithMandatoryExtensibleEnumTypeWithoutValues' "
@@ -113,7 +113,7 @@ public void MandatoryExtensibleEnumWithoutValuesProperty_UnsupportedType ()
     public void NullableExtensibleEnumWithoutValuesProperty_SupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(EnumTypeValidationDomainObjectClass).GetProperty("PropertyWithNullableExtensibleEnumTypeWithoutValues")),
           "PropertyWithNullableExtensibleEnumTypeWithoutValues",
           false,
@@ -122,10 +122,10 @@ public void NullableExtensibleEnumWithoutValuesProperty_SupportedType ()
           StorageClass.Persistent,
           null);
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithNullableExtensibleEnumTypeWithoutValues"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/MandatoryNetEnumTypeHasValuesDefinedValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/MandatoryNetEnumTypeHasValuesDefinedValidationRuleTest.cs
index c6d089616e..69f952c607 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/MandatoryNetEnumTypeHasValuesDefinedValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/MandatoryNetEnumTypeHasValuesDefinedValidationRuleTest.cs
@@ -10,21 +10,21 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Logical
   public class MandatoryNetEnumTypeHasValuesDefinedValidationRuleTest : ValidationRuleTestBase
   {
     private MandatoryNetEnumTypeHasValuesDefinedValidationRule _validationRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     [SetUp]
     public void SetUp ()
     {
       _validationRule = new MandatoryNetEnumTypeHasValuesDefinedValidationRule();
 
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(EnumTypeValidationDomainObjectClass));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixinsAndDefaultProperties(typeof(EnumTypeValidationDomainObjectClass));
     }
 
     [Test]
     public void PropertyWithOtherType_SupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(EnumTypeValidationDomainObjectClass).GetProperty("PropertyWithMandatoryOtherType")),
           "PropertyWithMandatoryOtherType",
           false,
@@ -33,10 +33,10 @@ public void PropertyWithOtherType_SupportedType ()
           StorageClass.Persistent,
           default(float));
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithMandatoryOtherType"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -45,7 +45,7 @@ public void PropertyWithOtherType_SupportedType ()
     public void MandatoryNetEnumWithValuesProperty_SupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(EnumTypeValidationDomainObjectClass).GetProperty("PropertyWithMandatoryNetEnumTypeWithValues")),
           "PropertyWithMandatoryNetEnumTypeWithValues",
           false,
@@ -54,10 +54,10 @@ public void MandatoryNetEnumWithValuesProperty_SupportedType ()
           StorageClass.Persistent,
           default(EnumTypeValidationDomainObjectClass.NetEnumTypeWithValues));
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithMandatoryNetEnumTypeWithValues"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -66,7 +66,7 @@ public void MandatoryNetEnumWithValuesProperty_SupportedType ()
     public void NullableNetEnumWithValuesProperty_SupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(EnumTypeValidationDomainObjectClass).GetProperty("PropertyWithNullableNetEnumTypeWithValues")),
           "PropertyWithNullableNetEnumTypeWithValues",
           false,
@@ -75,10 +75,10 @@ public void NullableNetEnumWithValuesProperty_SupportedType ()
           StorageClass.Persistent,
           null);
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithNullableNetEnumTypeWithValues"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -87,7 +87,7 @@ public void NullableNetEnumWithValuesProperty_SupportedType ()
     public void MandatoryNetEnumWithoutValuesProperty_UnsupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(EnumTypeValidationDomainObjectClass).GetProperty("PropertyWithMandatoryNetEnumTypeWithoutValues")),
           "PropertyWithMandatoryNetEnumTypeWithoutValues",
           false,
@@ -96,10 +96,10 @@ public void MandatoryNetEnumWithoutValuesProperty_UnsupportedType ()
           StorageClass.Persistent,
           default(EnumTypeValidationDomainObjectClass.NetEnumTypeWithoutValues));
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithMandatoryNetEnumTypeWithoutValues"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       var expectedMessage =
           "Enum type 'NetEnumTypeWithoutValues' cannot be used for property 'PropertyWithMandatoryNetEnumTypeWithoutValues' "
@@ -113,7 +113,7 @@ public void MandatoryNetEnumWithoutValuesProperty_UnsupportedType ()
     public void NullableNetEnumWithoutValuesProperty_SupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(EnumTypeValidationDomainObjectClass).GetProperty("PropertyWithNullableNetEnumTypeWithoutValues")),
           "PropertyWithNullableNetEnumTypeWithoutValues",
           false,
@@ -122,10 +122,10 @@ public void NullableNetEnumWithoutValuesProperty_SupportedType ()
           StorageClass.Persistent,
           null);
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithNullableNetEnumTypeWithoutValues"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/PropertyTypeIsSupportedValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/PropertyTypeIsSupportedValidationRuleTest.cs
index 7cfb182fa6..a386f46136 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/PropertyTypeIsSupportedValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/PropertyTypeIsSupportedValidationRuleTest.cs
@@ -27,21 +27,21 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Logical
   public class PropertyTypeIsSupportedValidationRuleTest : ValidationRuleTestBase
   {
     private PropertyTypeIsSupportedValidationRule _validationRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     [SetUp]
     public void SetUp ()
     {
       _validationRule = new PropertyTypeIsSupportedValidationRule();
 
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedValidationDomainObjectClass));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixinsAndDefaultProperties(typeof(DerivedValidationDomainObjectClass));
     }
 
     [Test]
     public void NoRelationProperty_SupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("PropertyWithStorageClassPersistent")),
           "PropertyWithStorageClassPersistent",
           false,
@@ -50,10 +50,10 @@ public void NoRelationProperty_SupportedType ()
           StorageClass.Persistent,
           null);
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithStorageClassPersistent"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -62,7 +62,7 @@ public void NoRelationProperty_SupportedType ()
     public void NoRelationProperty_UnsupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("PropertyWithTypeObjectWithStorageClassPersistent")),
           "PropertyWithTypeObjectWithStorageClassPersistent",
           false,
@@ -71,10 +71,10 @@ public void NoRelationProperty_UnsupportedType ()
           StorageClass.Persistent,
           null);
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("PropertyWithTypeObjectWithStorageClassPersistent"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       var expectedMessage =
           "The property type 'Object' is not supported. If you meant to declare a relation, 'Object' must be derived from 'DomainObject'. "
@@ -88,7 +88,7 @@ public void NoRelationProperty_UnsupportedType ()
     public void RelationProperty ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("RelationPropertyWithStorageClassPersistent")),
           "RelationPropertyWithStorageClassPersistent",
           true,
@@ -97,10 +97,10 @@ public void RelationProperty ()
           StorageClass.Persistent,
           null);
       propertyDefinition.SetStorageProperty(new FakeStoragePropertyDefinition("RelationPropertyWithStorageClassPersistent"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/RdbmsRelationEndPointCombinationIsSupportedValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/RdbmsRelationEndPointCombinationIsSupportedValidationRuleTest.cs
index a8d2a26b9a..0f62e433fa 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/RdbmsRelationEndPointCombinationIsSupportedValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/RdbmsRelationEndPointCombinationIsSupportedValidationRuleTest.cs
@@ -28,7 +28,7 @@ public class RdbmsRelationEndPointCombinationIsSupportedValidationRuleTest : Val
   {
     private RelationEndPointCombinationIsSupportedValidationRule _validationRule;
 
-    private ClassDefinition _orderClass;
+    private TypeDefinition _orderClass;
 
     [SetUp]
     public void SetUp ()
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/SortExpressionIsSupportedForCardinalityOfRelationPropertyValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/SortExpressionIsSupportedForCardinalityOfRelationPropertyValidationRuleTest.cs
index 1431387c3c..0a3c36d62f 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/SortExpressionIsSupportedForCardinalityOfRelationPropertyValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/SortExpressionIsSupportedForCardinalityOfRelationPropertyValidationRuleTest.cs
@@ -27,19 +27,19 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Logical
   public class SortExpressionIsSupportedForCardinalityOfRelationPropertyValidationRuleTest : ValidationRuleTestBase
   {
     private SortExpressionIsSupportedForCardinalityOfRelationPropertyValidationRule _validationRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     [SetUp]
     public void SetUp ()
     {
       _validationRule = new SortExpressionIsSupportedForCardinalityOfRelationPropertyValidationRule();
-      _classDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
+      _typeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
     }
 
     [Test]
     public void NoVirtualRelationEndPointDefinition ()
     {
-      var endPointDefinition = new AnonymousRelationEndPointDefinition(_classDefinition);
+      var endPointDefinition = new AnonymousRelationEndPointDefinition(_typeDefinition);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -51,7 +51,7 @@ public void NoVirtualRelationEndPointDefinition ()
     public void CardinalityIsMany ()
     {
       var endPointDefinition = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _classDefinition, "PropertyName", false, typeof(DomainObjectCollection));
+          _typeDefinition, "PropertyName", false, typeof(DomainObjectCollection));
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -63,7 +63,7 @@ public void CardinalityIsMany ()
     public void CardinalityIsOne_And_EndPointDefinitionHasNoSortExpression ()
     {
       var endPointDefinition = VirtualObjectRelationEndPointDefinitionFactory.Create(
-        _classDefinition, "PropertyName", false, typeof(DerivedValidationDomainObjectClass));
+        _typeDefinition, "PropertyName", false, typeof(DerivedValidationDomainObjectClass));
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -75,17 +75,17 @@ public void CardinalityIsOne_And_EndPointDefinitionHasNoSortExpression ()
     public void CardinalityOne_And_EndPointDefinitionsHaveSortExpression ()
     {
       var leftEndPointDefinition = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _classDefinition, "PropertyName", false, typeof(DerivedValidationDomainObjectClass));
+          _typeDefinition, "PropertyName", false, typeof(DerivedValidationDomainObjectClass));
 
       var rightEndPointDefinition = VirtualObjectRelationEndPointDefinitionFactory.Create(
-          _classDefinition, "PropertyName", false, typeof(DomainObject), "SortExpression");
+          _typeDefinition, "PropertyName", false, typeof(DomainObject), "SortExpression");
 
       var relationDefinition = new RelationDefinition("Test", leftEndPointDefinition, rightEndPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
 
       var expectedMessage =
-        "Property 'PropertyName' of class 'Order' must not specify a SortExpression, because cardinality is equal to 'one'.\r\n\r\n"
+        "Property 'PropertyName' of type 'Order' must not specify a SortExpression, because cardinality is equal to 'one'.\r\n\r\n"
         + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order\r\nProperty: PropertyName";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/SortExpressionIsValidValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/SortExpressionIsValidValidationRuleTest.cs
index 5ab12724c4..ff28fb3f25 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/SortExpressionIsValidValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/SortExpressionIsValidValidationRuleTest.cs
@@ -40,14 +40,14 @@ public void SetUp ()
     [Test]
     public void ValidSortExpressionWithSortingDirection_WithDomainObjectCollectionRelationEndPointDefinition ()
     {
-      var classDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
+      var typeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
       var propertyInformationStub = new Mock<IPropertyInformation>();
       var sortExpressionDefinitionProvider = new SortExpressionDefinitionProvider();
       var sortExpressionDefinition = new Lazy<SortExpressionDefinition>(
-          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInformationStub.Object, classDefinition, "OrderNumber desc"));
+          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInformationStub.Object, typeDefinition, "OrderNumber desc"));
 
       var endPointDefinition = new DomainObjectCollectionRelationEndPointDefinition(
-          classDefinition,
+          typeDefinition,
           "Orders",
           false,
           sortExpressionDefinition,
@@ -63,14 +63,14 @@ public void ValidSortExpressionWithSortingDirection_WithDomainObjectCollectionRe
     [Test]
     public void ValidSortExpressionWithSortingDirection_WithVirtualCollectionRelationEndPointDefinition ()
     {
-      var classDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(ProductReview)];
+      var typeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(ProductReview)];
       var propertyInformationStub = new Mock<IPropertyInformation>();
       var sortExpressionDefinitionProvider = new SortExpressionDefinitionProvider();
       var sortExpressionDefinition = new Lazy<SortExpressionDefinition>(
-          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInformationStub.Object, classDefinition, "CreatedAt DESC"));
+          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInformationStub.Object, typeDefinition, "CreatedAt DESC"));
 
       var endPointDefinition = new VirtualCollectionRelationEndPointDefinition(
-          classDefinition,
+          typeDefinition,
           "Reviews",
           false,
           sortExpressionDefinition,
@@ -86,14 +86,14 @@ public void ValidSortExpressionWithSortingDirection_WithVirtualCollectionRelatio
     [Test]
     public void ValidSortExpressionWithoutSortingDirection_WithDomainObjectCollectionRelationEndPointDefinition ()
     {
-      var classDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
+      var typeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
       var propertyInformationStub = new Mock<IPropertyInformation>();
       var sortExpressionDefinitionProvider = new SortExpressionDefinitionProvider();
       var sortExpressionDefinition = new Lazy<SortExpressionDefinition>(
-          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInformationStub.Object, classDefinition, "OrderNumber"));
+          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInformationStub.Object, typeDefinition, "OrderNumber"));
 
       var endPointDefinition = new DomainObjectCollectionRelationEndPointDefinition(
-          classDefinition, "Orders", false, sortExpressionDefinition, propertyInformationStub.Object);
+          typeDefinition, "Orders", false, sortExpressionDefinition, propertyInformationStub.Object);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
       endPointDefinition.SetRelationDefinition(relationDefinition);
 
@@ -105,14 +105,14 @@ public void ValidSortExpressionWithoutSortingDirection_WithDomainObjectCollectio
     [Test]
     public void ValidSortExpressionWithoutSortingDirection_WithVirtualCollectionRelationEndPointDefinition ()
     {
-      var classDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(ProductReview)];
+      var typeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(ProductReview)];
       var propertyInformationStub = new Mock<IPropertyInformation>();
       var sortExpressionDefinitionProvider = new SortExpressionDefinitionProvider();
       var sortExpressionDefinition = new Lazy<SortExpressionDefinition>(
-          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInformationStub.Object, classDefinition, "CreatedAt"));
+          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInformationStub.Object, typeDefinition, "CreatedAt"));
 
       var endPointDefinition = new VirtualCollectionRelationEndPointDefinition(
-          classDefinition, "Reviews", false, sortExpressionDefinition, propertyInformationStub.Object);
+          typeDefinition, "Reviews", false, sortExpressionDefinition, propertyInformationStub.Object);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
       endPointDefinition.SetRelationDefinition(relationDefinition);
 
@@ -124,14 +124,14 @@ public void ValidSortExpressionWithoutSortingDirection_WithVirtualCollectionRela
     [Test]
     public void InvalidSortExpression_WithDomainObjectCollectionRelationEndPointDefinition ()
     {
-      var classDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
+      var typeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
       var propertyInfo = PropertyInfoAdapter.Create(typeof(Customer).GetProperty("Orders"));
       var sortExpressionDefinitionProvider = new SortExpressionDefinitionProvider();
       var sortExpressionDefinition = new Lazy<SortExpressionDefinition>(
-          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInfo, classDefinition, "Test"));
+          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInfo, typeDefinition, "Test"));
 
       var endPointDefinition = new DomainObjectCollectionRelationEndPointDefinition(
-          classDefinition,
+          typeDefinition,
           "Orders",
           false,
           sortExpressionDefinition,
@@ -152,14 +152,14 @@ public void InvalidSortExpression_WithDomainObjectCollectionRelationEndPointDefi
     [Test]
     public void InvalidSortExpression_WithVirtualCollectionRelationEndPointDefinition ()
     {
-      var classDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(ProductReview)];
+      var typeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(ProductReview)];
       var propertyInfo = PropertyInfoAdapter.Create(typeof(Product).GetProperty("Reviews"));
       var sortExpressionDefinitionProvider = new SortExpressionDefinitionProvider();
       var sortExpressionDefinition = new Lazy<SortExpressionDefinition>(
-          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInfo, classDefinition, "Test"));
+          () => sortExpressionDefinitionProvider.GetSortExpression(propertyInfo, typeDefinition, "Test"));
 
       var endPointDefinition = new VirtualCollectionRelationEndPointDefinition(
-          classDefinition,
+          typeDefinition,
           "Reviews",
           false,
           sortExpressionDefinition,
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/StorageClassIsSupportedValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/StorageClassIsSupportedValidationRuleTest.cs
index 15a563137b..3f4900e839 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/StorageClassIsSupportedValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/StorageClassIsSupportedValidationRuleTest.cs
@@ -27,7 +27,7 @@ public class StorageClassIsSupportedValidationRuleTest : ValidationRuleTestBase
   {
     private StorageClassIsSupportedValidationRule _validationRule;
     private Type _type;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     [SetUp]
     public void SetUp ()
@@ -35,17 +35,17 @@ public void SetUp ()
       _validationRule = new StorageClassIsSupportedValidationRule();
 
       _type = typeof(DerivedValidationDomainObjectClass);
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(_type);
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixinsAndDefaultProperties(_type);
     }
 
     [Test]
     public void PropertyWithoutStorageClassAttribute ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _type, "Property");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _type, "Property");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -53,11 +53,11 @@ public void PropertyWithoutStorageClassAttribute ()
     [Test]
     public void PropertyWithStorageClassPersistent ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _type, "PropertyWithStorageClassPersistent");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _type, "PropertyWithStorageClassPersistent");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -65,11 +65,11 @@ public void PropertyWithStorageClassPersistent ()
     [Test]
     public void PropertyWithStorageClassTransaction ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _type, "PropertyWithStorageClassTransaction");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _type, "PropertyWithStorageClassTransaction");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -77,14 +77,14 @@ public void PropertyWithStorageClassTransaction ()
     [Test]
     public void PropertyWithStorageClassNone ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _type, "PropertyWithStorageClassNone");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _type, "PropertyWithStorageClassNone");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       var expectedMessage = "Only StorageClass.Persistent and StorageClass.Transaction are supported for property 'PropertyWithStorageClassNone' of "
-        +"class 'DerivedValidationDomainObjectClass'.\r\n\r\n"
+        +"type 'DerivedValidationDomainObjectClass'.\r\n\r\n"
         +"Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.DerivedValidationDomainObjectClass\r\n"
         +"Property: PropertyWithStorageClassNone";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/StorageGroupTypesAreSameWithinInheritanceTreeRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/StorageGroupTypesAreSameWithinInheritanceTreeRuleTest.cs
index b0c0179789..95c87bf653 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/StorageGroupTypesAreSameWithinInheritanceTreeRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/StorageGroupTypesAreSameWithinInheritanceTreeRuleTest.cs
@@ -16,9 +16,11 @@
 // 
 using System;
 using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
 using Remotion.Data.DomainObjects.Mapping.Validation.Logical;
 using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation;
 using Remotion.Data.DomainObjects.UnitTests.Persistence.Configuration;
+using Remotion.Reflection;
 
 namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Logical
 {
@@ -36,10 +38,10 @@ public void SetUp ()
     [Test]
     public void ClassWithoutBaseClass ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(
           classType: typeof(BaseOfBaseValidationDomainObjectClass),
           storageGroupType: typeof(DBStorageGroupAttribute));
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -48,7 +50,7 @@ public void ClassWithoutBaseClass ()
     public void ClassWithBaseClass_ClassesWithoutStorageGroupAttribute ()
     {
       var baseClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(BaseOfBaseValidationDomainObjectClass), storageGroupType: null);
-      var derivedClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(
+      var derivedClassDefinition = TypeDefinitionObjectMother.CreateClassDefinition(
           classType: typeof(BaseOfBaseValidationDomainObjectClass),
           baseClass: baseClassDefinition,
           storageGroupType: null);
@@ -64,7 +66,7 @@ public void ClassWithBaseClass_ClassesWithSameStorageGroupAttribute ()
       var baseClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(
           classType: typeof(BaseOfBaseValidationDomainObjectClass),
           storageGroupType: typeof(DBStorageGroupAttribute));
-      var derivedClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(
+      var derivedClassDefinition = TypeDefinitionObjectMother.CreateClassDefinition(
           classType: typeof(BaseOfBaseValidationDomainObjectClass),
           baseClass: baseClassDefinition,
           storageGroupType: typeof(DBStorageGroupAttribute));
@@ -80,7 +82,7 @@ public void ClassWithBaseClass_ClassesWithDifferentStorageGroupAttribute ()
       var baseClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(
           classType: typeof(BaseOfBaseValidationDomainObjectClass),
           storageGroupType: typeof(DBStorageGroupAttribute));
-      var derivedClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(
+      var derivedClassDefinition = TypeDefinitionObjectMother.CreateClassDefinition(
           classType: typeof(BaseValidationDomainObjectClass),
           baseClass: baseClassDefinition,
           storageGroupType: typeof(StubStorageGroup1Attribute));
@@ -92,5 +94,15 @@ public void ClassWithBaseClass_ClassesWithDifferentStorageGroupAttribute ()
           + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.BaseValidationDomainObjectClass";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
     }
+
+    [Test]
+    public void IgnoresArgumentsOfTypeOtherThanClassDefinition ()
+    {
+      var typeDefinitionForUnresolvedRelationPropertyType = new TypeDefinitionForUnresolvedRelationPropertyType(typeof(string), new NullPropertyInformation());
+
+      Assert.That(() => _validationRule.Validate(typeDefinitionForUnresolvedRelationPropertyType),
+          Throws.InvalidOperationException.With
+              .Message.EqualTo("Only class definitions are supported"));
+    }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/VirtualRelationEndPointCardinalityMatchesPropertyTypeValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/VirtualRelationEndPointCardinalityMatchesPropertyTypeValidationRuleTest.cs
index 2f4b0f843c..226f4f954a 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/VirtualRelationEndPointCardinalityMatchesPropertyTypeValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/VirtualRelationEndPointCardinalityMatchesPropertyTypeValidationRuleTest.cs
@@ -32,19 +32,19 @@ private class DerivedObjectList<T> : ObjectList<T> where T : DomainObject
     }
 
     private VirtualRelationEndPointCardinalityMatchesPropertyTypeValidationRule _validationRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     [SetUp]
     public void SetUp ()
     {
       _validationRule = new VirtualRelationEndPointCardinalityMatchesPropertyTypeValidationRule();
-      _classDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
+      _typeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
     }
 
     [Test]
     public void NoVirtualRelationEndPointDefinition ()
     {
-      var endPointDefinition = new AnonymousRelationEndPointDefinition(_classDefinition);
+      var endPointDefinition = new AnonymousRelationEndPointDefinition(_typeDefinition);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -56,9 +56,9 @@ public void NoVirtualRelationEndPointDefinition ()
     public void VirtualRelationEndPointDefinitionWithCardinalityOne_And_PropertyTypeNotAssignableToDomainObject ()
     {
       var leftEndPointDefinition =
-          VirtualObjectRelationEndPointDefinitionFactory.Create(_classDefinition, "Left", false, typeof(string));
+          VirtualObjectRelationEndPointDefinitionFactory.Create(_typeDefinition, "Left", false, typeof(string));
       var rightEndPointDefinition =
-          VirtualObjectRelationEndPointDefinitionFactory.Create(_classDefinition, "Right", false, typeof(DomainObject));
+          VirtualObjectRelationEndPointDefinitionFactory.Create(_typeDefinition, "Right", false, typeof(DomainObject));
       var relationDefinition = new RelationDefinition("Test", leftEndPointDefinition, rightEndPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -74,7 +74,7 @@ public void VirtualRelationEndPointDefinitionWithCardinalityOne_And_PropertyType
     public void VirtualRelationEndPointDefinitionWithCardinalityOne_And_PropertyTypeIsDomainObject ()
     {
       var endPointDefinition = VirtualObjectRelationEndPointDefinitionFactory.Create(
-         _classDefinition, "PropertyName", false, typeof(DomainObject));
+         _typeDefinition, "PropertyName", false, typeof(DomainObject));
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -86,7 +86,7 @@ public void VirtualRelationEndPointDefinitionWithCardinalityOne_And_PropertyType
     public void VirtualRelationEndPointDefinitionWithCardinalityOne_And_PropertyTypeDerivedFromDomainObject ()
     {
       var endPointDefinition = VirtualObjectRelationEndPointDefinitionFactory.Create(
-         _classDefinition, "PropertyName", false, typeof(BaseOfBaseValidationDomainObjectClass));
+         _typeDefinition, "PropertyName", false, typeof(BaseOfBaseValidationDomainObjectClass));
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -98,7 +98,7 @@ public void VirtualRelationEndPointDefinitionWithCardinalityOne_And_PropertyType
     public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTypeIsDomainObjectCollection ()
     {
       var endPointDefinition = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _classDefinition, "PropertyName", false, typeof(DomainObjectCollection));
+          _typeDefinition, "PropertyName", false, typeof(DomainObjectCollection));
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -114,7 +114,7 @@ public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTyp
     public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTypeIsObjectList ()
     {
       var endPointDefinition = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-         _classDefinition, "PropertyName", false, typeof(ObjectList<BaseOfBaseValidationDomainObjectClass>));
+         _typeDefinition, "PropertyName", false, typeof(ObjectList<BaseOfBaseValidationDomainObjectClass>));
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -126,7 +126,7 @@ public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTyp
     public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTypeIsDerivedFromObjectList ()
     {
       var endPointDefinition = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-         _classDefinition, "PropertyName", false, typeof(DerivedObjectList<BaseOfBaseValidationDomainObjectClass>));
+         _typeDefinition, "PropertyName", false, typeof(DerivedObjectList<BaseOfBaseValidationDomainObjectClass>));
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -138,9 +138,9 @@ public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTyp
     public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTypeIsNotAssignableToObjectList ()
     {
       var leftEndPointDefinition = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _classDefinition, "PropertyName", false, typeof(DomainObjectCollection));
+          _typeDefinition, "PropertyName", false, typeof(DomainObjectCollection));
       var rightEndPointDefinition = VirtualObjectRelationEndPointDefinitionFactory.Create(
-          _classDefinition, "PropertyName", false, typeof(DomainObject));
+          _typeDefinition, "PropertyName", false, typeof(DomainObject));
       var relationDefinition = new RelationDefinition("Test", leftEndPointDefinition, rightEndPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -156,7 +156,7 @@ public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTyp
     public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTypeIsIObjectList ()
     {
       var endPointDefinition = VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          _classDefinition, "PropertyName", false, typeof(IObjectList<BaseOfBaseValidationDomainObjectClass>));
+          _typeDefinition, "PropertyName", false, typeof(IObjectList<BaseOfBaseValidationDomainObjectClass>));
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -168,9 +168,9 @@ public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTyp
     public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTypeIsNotIObjectList ()
     {
       var leftEndPointDefinition = VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          _classDefinition, "PropertyName", false, typeof(DomainObjectCollection));
+          _typeDefinition, "PropertyName", false, typeof(DomainObjectCollection));
       var rightEndPointDefinition = VirtualObjectRelationEndPointDefinitionFactory.Create(
-          _classDefinition, "PropertyName", false, typeof(DomainObject));
+          _typeDefinition, "PropertyName", false, typeof(DomainObject));
       var relationDefinition = new RelationDefinition("Test", leftEndPointDefinition, rightEndPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -186,9 +186,9 @@ public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTyp
     public void VirtualRelationEndPointDefinitionWithCardinalityMany_And_PropertyTypeIsDerivedFromIObjectList ()
     {
       var leftEndPointDefinition = VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          _classDefinition, "PropertyName", false, typeof(IDerivedObjectList<BaseOfBaseValidationDomainObjectClass>));
+          _typeDefinition, "PropertyName", false, typeof(IDerivedObjectList<BaseOfBaseValidationDomainObjectClass>));
       var rightEndPointDefinition = VirtualObjectRelationEndPointDefinitionFactory.Create(
-          _classDefinition, "PropertyName", false, typeof(DomainObject));
+          _typeDefinition, "PropertyName", false, typeof(DomainObject));
       var relationDefinition = new RelationDefinition("Test", leftEndPointDefinition, rightEndPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/VirtualRelationEndPointPropertyTypeIsSupportedValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/VirtualRelationEndPointPropertyTypeIsSupportedValidationRuleTest.cs
index 5b0eb58046..8ad33c2c6d 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/VirtualRelationEndPointPropertyTypeIsSupportedValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Logical/VirtualRelationEndPointPropertyTypeIsSupportedValidationRuleTest.cs
@@ -31,19 +31,19 @@ private class DerivedObjectList<T> : ObjectList<T> where T : DomainObject
     }
 
     private VirtualRelationEndPointPropertyTypeIsSupportedValidationRule _validationRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     [SetUp]
     public void SetUp ()
     {
       _validationRule = new VirtualRelationEndPointPropertyTypeIsSupportedValidationRule();
-      _classDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
+      _typeDefinition = FakeMappingConfiguration.Current.TypeDefinitions[typeof(Order)];
     }
 
     [Test]
     public void NoVirtualRelationEndPointDefinition ()
     {
-      var endPointDefinition = new AnonymousRelationEndPointDefinition(_classDefinition);
+      var endPointDefinition = new AnonymousRelationEndPointDefinition(_typeDefinition);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -56,7 +56,7 @@ public void PropertyTypIsObjectList ()
     {
       var propertyType = typeof(ObjectList<BaseOfBaseValidationDomainObjectClass>);
       var endPointDefinition =
-          DomainObjectCollectionRelationEndPointDefinitionFactory.Create(_classDefinition, "Property", false, propertyType);
+          DomainObjectCollectionRelationEndPointDefinitionFactory.Create(_typeDefinition, "Property", false, propertyType);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -69,7 +69,7 @@ public void PropertyTypeIsDerivedFromObjectList ()
     {
       var propertyType = typeof(DerivedObjectList<BaseOfBaseValidationDomainObjectClass>);
       var endPointDefinition =
-          DomainObjectCollectionRelationEndPointDefinitionFactory.Create(_classDefinition, "Property", false, propertyType);
+          DomainObjectCollectionRelationEndPointDefinitionFactory.Create(_typeDefinition, "Property", false, propertyType);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -82,7 +82,7 @@ public void PropertyTypIsIObjectList ()
     {
       var propertyType = typeof(IObjectList<BaseOfBaseValidationDomainObjectClass>);
       var endPointDefinition =
-          VirtualCollectionRelationEndPointDefinitionFactory.Create(_classDefinition, "Property", false, propertyType);
+          VirtualCollectionRelationEndPointDefinitionFactory.Create(_typeDefinition, "Property", false, propertyType);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -95,7 +95,7 @@ public void PropertyTypeIsDomainObject ()
     {
       var propertyType = typeof(DomainObject);
       var endPointDefinition =
-          VirtualObjectRelationEndPointDefinitionFactory.Create(_classDefinition, "Property", false, propertyType);
+          VirtualObjectRelationEndPointDefinitionFactory.Create(_typeDefinition, "Property", false, propertyType);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -108,7 +108,7 @@ public void PropertyTypeIsSubclassOfDomainObject ()
     {
       var propertyType = typeof(BaseOfBaseValidationDomainObjectClass);
       var endPointDefinition =
-          VirtualObjectRelationEndPointDefinitionFactory.Create(_classDefinition, "Property", false, propertyType);
+          VirtualObjectRelationEndPointDefinitionFactory.Create(_typeDefinition, "Property", false, propertyType);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -120,15 +120,15 @@ public void PropertyTypeIsSubclassOfDomainObject ()
     public void LeftEndpointPropertyType_NotAssignableToObjectListOrDomainObjectOrOfTypeIObjectList ()
     {
       var leftEndPointDefinition =
-          VirtualObjectRelationEndPointDefinitionFactory.Create(_classDefinition, "Left", false, typeof(string));
+          VirtualObjectRelationEndPointDefinitionFactory.Create(_typeDefinition, "Left", false, typeof(string));
       var rightEndPointDefinition =
-          VirtualObjectRelationEndPointDefinitionFactory.Create(_classDefinition, "Right", false, typeof(DomainObject));
+          VirtualObjectRelationEndPointDefinitionFactory.Create(_typeDefinition, "Right", false, typeof(DomainObject));
       var relationDefinition = new RelationDefinition("Test", leftEndPointDefinition, rightEndPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
 
       var expectedMessage =
-          "Virtual property 'Left' of class 'Order' is of type 'String', but must be assignable to 'DomainObject' or 'ObjectList`1' or be of type 'IObjectList`1'.\r\n\r\n"
+          "Virtual property 'Left' of type 'Order' is of type 'String', but must be assignable to 'DomainObject' or 'ObjectList`1' or be of type 'IObjectList`1'.\r\n\r\n"
           + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order\r\n"
           + "Property: Left";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
@@ -138,15 +138,15 @@ public void LeftEndpointPropertyType_NotAssignableToObjectListOrDomainObjectOrOf
     public void RightEndpointPropertyType_NotAssignableToIObjectListOrObjectListOrDomainObjectOrOfTypeIObjectList ()
     {
       var leftEndPointDefinition =
-          DomainObjectCollectionRelationEndPointDefinitionFactory.Create(_classDefinition, "Left", false, typeof(ObjectList<>));
+          DomainObjectCollectionRelationEndPointDefinitionFactory.Create(_typeDefinition, "Left", false, typeof(ObjectList<>));
       var rightEndPointDefinition =
-          VirtualObjectRelationEndPointDefinitionFactory.Create(_classDefinition, "Right", false, typeof(string));
+          VirtualObjectRelationEndPointDefinitionFactory.Create(_typeDefinition, "Right", false, typeof(string));
       var relationDefinition = new RelationDefinition("Test", leftEndPointDefinition, rightEndPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
 
       var expectedMessage =
-          "Virtual property 'Right' of class 'Order' is of type 'String', but must be assignable to 'DomainObject' or 'ObjectList`1' or be of type 'IObjectList`1'.\r\n\r\n"
+          "Virtual property 'Right' of type 'Order' is of type 'String', but must be assignable to 'DomainObject' or 'ObjectList`1' or be of type 'IObjectList`1'.\r\n\r\n"
           + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Integration.Order\r\n"
           + "Property: Right";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/PersistenceMappingValidatorTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/PersistenceMappingValidatorTest.cs
index 263b9a8428..50464bca34 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/PersistenceMappingValidatorTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/PersistenceMappingValidatorTest.cs
@@ -27,9 +27,9 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation
   [TestFixture]
   public class PersistenceMappingValidatorTest
   {
-    private ClassDefinition _classDefinition1;
-    private ClassDefinition _classDefinition2;
-    private ClassDefinition _classDefinition3;
+    private TypeDefinition _typeDefinition1;
+    private TypeDefinition _typeDefinition2;
+    private TypeDefinition _typeDefinition3;
     private MappingValidationResult _fakeValidMappingValidationResult;
     private MappingValidationResult _fakeInvalidMappingValidationResult;
     private Mock<IPersistenceMappingValidationRule> _validationRuleMock1;
@@ -40,9 +40,9 @@ public class PersistenceMappingValidatorTest
     public void SetUp ()
     {
       var type = typeof(DerivedValidationDomainObjectClass);
-      _classDefinition1 = ClassDefinitionObjectMother.CreateClassDefinition(classType: type);
-      _classDefinition2 = ClassDefinitionObjectMother.CreateClassDefinition(classType: type);
-      _classDefinition3 = ClassDefinitionObjectMother.CreateClassDefinition(classType: type);
+      _typeDefinition1 = TypeDefinitionObjectMother.CreateClassDefinition(classType: type);
+      _typeDefinition2 = TypeDefinitionObjectMother.CreateClassDefinition(classType: type);
+      _typeDefinition3 = TypeDefinitionObjectMother.CreateClassDefinition(classType: type);
 
       _validationRuleMock1 = new Mock<IPersistenceMappingValidationRule>(MockBehavior.Strict);
       _validationRuleMock2 = new Mock<IPersistenceMappingValidationRule>(MockBehavior.Strict);
@@ -53,13 +53,13 @@ public void SetUp ()
     }
 
     [Test]
-    public void ValidateWithOneRuleAndClassDefinition_ValidResult ()
+    public void ValidateWithOneRuleAndTypeDefinition_ValidResult ()
     {
       var validator = new PersistenceMappingValidator(_validationRuleMock1.Object);
 
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[] { _fakeValidMappingValidationResult}).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[] { _fakeValidMappingValidationResult}).Verifiable();
 
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1 }).ToArray();
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1 }).ToArray();
 
       _validationRuleMock1.Verify();
       Assert.That(validator.ValidationRules.Count, Is.EqualTo(1));
@@ -67,13 +67,13 @@ public void ValidateWithOneRuleAndClassDefinition_ValidResult ()
     }
 
     [Test]
-    public void ValidateWithOneRuleAndClassDefinition_InvalidResult ()
+    public void ValidateWithOneRuleAndTypeDefinition_InvalidResult ()
     {
       var validator = new PersistenceMappingValidator(_validationRuleMock1.Object);
 
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[]{ _fakeInvalidMappingValidationResult}).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[]{ _fakeInvalidMappingValidationResult}).Verifiable();
 
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1 }).ToArray();
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1 }).ToArray();
 
       _validationRuleMock1.Verify();
       Assert.That(validator.ValidationRules.Count, Is.EqualTo(1));
@@ -82,21 +82,21 @@ public void ValidateWithOneRuleAndClassDefinition_InvalidResult ()
     }
 
     [Test]
-    public void ValidateWithSeveralRulesAndClassDefinitions_ValidResult ()
+    public void ValidateWithSeveralRulesAndTypeDefinitions_ValidResult ()
     {
       var validator = new PersistenceMappingValidator(_validationRuleMock1.Object, _validationRuleMock2.Object, _validationRuleMock3.Object);
 
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[]{ _fakeValidMappingValidationResult}).Verifiable();
 
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1, _classDefinition2, _classDefinition3 }).ToArray();
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1, _typeDefinition2, _typeDefinition3 }).ToArray();
 
       _validationRuleMock1.Verify();
       Assert.That(validator.ValidationRules.Count, Is.EqualTo(3));
@@ -104,21 +104,21 @@ public void ValidateWithSeveralRulesAndClassDefinitions_ValidResult ()
     }
 
     [Test]
-    public void ValidateWithSeveralRulesAndClassDefinitions_InvalidResult ()
+    public void ValidateWithSeveralRulesAndTypeDefinitions_InvalidResult ()
     {
       var validator = new PersistenceMappingValidator(_validationRuleMock1.Object, _validationRuleMock2.Object, _validationRuleMock3.Object);
 
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
-
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1, _classDefinition2, _classDefinition3 }).ToArray();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
+
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1, _typeDefinition2, _typeDefinition3 }).ToArray();
 
       _validationRuleMock1.Verify();
       Assert.That(validator.ValidationRules.Count, Is.EqualTo(3));
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/PropertyDefinitionValidatorTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/PropertyDefinitionValidatorTest.cs
index 99c10ab8bf..340cd01ff5 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/PropertyDefinitionValidatorTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/PropertyDefinitionValidatorTest.cs
@@ -27,9 +27,9 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation
   [TestFixture]
   public class PropertyDefinitionValidatorTest
   {
-    private ClassDefinition _classDefinition1;
-    private ClassDefinition _classDefinition2;
-    private ClassDefinition _classDefinition3;
+    private TypeDefinition _typeDefinition1;
+    private TypeDefinition _typeDefinition2;
+    private TypeDefinition _typeDefinition3;
     private MappingValidationResult _fakeValidMappingValidationResult;
     private MappingValidationResult _fakeInvalidMappingValidationResult;
     private Mock<IPropertyDefinitionValidationRule> _validationRuleMock1;
@@ -39,9 +39,9 @@ public class PropertyDefinitionValidatorTest
     [SetUp]
     public void SetUp ()
     {
-      _classDefinition1 = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
-      _classDefinition2 = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
-      _classDefinition3 = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
+      _typeDefinition1 = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
+      _typeDefinition2 = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
+      _typeDefinition3 = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
 
       _validationRuleMock1 = new Mock<IPropertyDefinitionValidationRule>(MockBehavior.Strict);
       _validationRuleMock2 = new Mock<IPropertyDefinitionValidationRule>(MockBehavior.Strict);
@@ -52,13 +52,13 @@ public void SetUp ()
     }
 
     [Test]
-    public void ValidateWithOneRuleAndClassDefinition_ValidResult ()
+    public void ValidateWithOneRuleAndTypeDefinition_ValidResult ()
     {
       var validator = new PropertyDefinitionValidator(_validationRuleMock1.Object);
 
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[]{_fakeValidMappingValidationResult}).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[]{_fakeValidMappingValidationResult}).Verifiable();
 
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1 }).ToArray();
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1 }).ToArray();
 
       _validationRuleMock1.Verify();
       Assert.That(validator.ValidationRules.Count, Is.EqualTo(1));
@@ -66,13 +66,13 @@ public void ValidateWithOneRuleAndClassDefinition_ValidResult ()
     }
 
     [Test]
-    public void ValidateWithOneRuleAndClassDefinition_InvalidResult ()
+    public void ValidateWithOneRuleAndTypeDefinition_InvalidResult ()
     {
       var validator = new PropertyDefinitionValidator(_validationRuleMock1.Object);
 
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[]{_fakeInvalidMappingValidationResult}).Verifiable();
 
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1 }).ToArray();
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1 }).ToArray();
 
       _validationRuleMock1.Verify();
       Assert.That(validator.ValidationRules.Count, Is.EqualTo(1));
@@ -81,21 +81,21 @@ public void ValidateWithOneRuleAndClassDefinition_InvalidResult ()
     }
 
     [Test]
-    public void ValidateWithSeveralRulesAndClassDefinitions_ValidResult ()
+    public void ValidateWithSeveralRulesAndTypeDefinitions_ValidResult ()
     {
       var validator = new PropertyDefinitionValidator(_validationRuleMock1.Object, _validationRuleMock2.Object, _validationRuleMock3.Object);
 
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[] { _fakeValidMappingValidationResult }).Verifiable();
 
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1, _classDefinition2, _classDefinition3 }).ToArray();
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1, _typeDefinition2, _typeDefinition3 }).ToArray();
 
       _validationRuleMock1.Verify();
       Assert.That(validator.ValidationRules.Count, Is.EqualTo(3));
@@ -103,21 +103,21 @@ public void ValidateWithSeveralRulesAndClassDefinitions_ValidResult ()
     }
 
     [Test]
-    public void ValidateWithSeveralRulesAndClassDefinitions_InvalidResult ()
+    public void ValidateWithSeveralRulesAndTypeDefinitions_InvalidResult ()
     {
       var validator = new PropertyDefinitionValidator(_validationRuleMock1.Object, _validationRuleMock2.Object, _validationRuleMock3.Object);
 
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
-      _validationRuleMock1.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
-      _validationRuleMock2.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition1)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition2)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
-      _validationRuleMock3.Setup(mock => mock.Validate(_classDefinition3)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
-
-      var mappingValidationResults = validator.Validate(new[] { _classDefinition1, _classDefinition2, _classDefinition3 }).ToArray();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition1)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition2)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition3)).Returns(new[] { _fakeInvalidMappingValidationResult }).Verifiable();
+
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1, _typeDefinition2, _typeDefinition3 }).ToArray();
 
       _validationRuleMock1.Verify();
       Assert.That(validator.ValidationRules.Count, Is.EqualTo(3));
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/ClassDefinitionTypeIsSubclassOfDomainObjectValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/ClassDefinitionTypeIsSubclassOfDomainObjectValidationRuleTest.cs
index a7aa251b47..53ef329af0 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/ClassDefinitionTypeIsSubclassOfDomainObjectValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/ClassDefinitionTypeIsSubclassOfDomainObjectValidationRuleTest.cs
@@ -16,8 +16,10 @@
 // 
 using System;
 using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
 using Remotion.Data.DomainObjects.Mapping.Validation.Reflection;
 using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation;
+using Remotion.Reflection;
 
 namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Reflection
 {
@@ -35,9 +37,9 @@ public void SetUp ()
     [Test]
     public void ClassDefinitionTypeIsSubClassOfDomainObject ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedValidationDomainObjectClass));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedValidationDomainObjectClass));
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -45,9 +47,9 @@ public void ClassDefinitionTypeIsSubClassOfDomainObject ()
     [Test]
     public void ClassDefinitionTypeIsNoSubClassOfDomainObject ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition("String", typeof(string));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition("String", typeof(string));
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       var expectedMessage = "Type 'String' of class 'String' is not assignable to 'DomainObject'.\r\n\r\nDeclaring type: System.String";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRuleTest.cs
index 0f3dadf520..23e3e444ac 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRuleTest.cs
@@ -35,9 +35,9 @@ public void SetUp ()
     [Test]
     public void NonAbstractType_WithoutLegacyConstructor ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(NonAbstractClassWithoutLegacyConstructor));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(NonAbstractClassWithoutLegacyConstructor));
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -45,9 +45,9 @@ public void NonAbstractType_WithoutLegacyConstructor ()
     [Test]
     public void NonAbstractType_WithLegacyConstructor ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(NonAbstractClassWithLegacyConstructor));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(NonAbstractClassWithLegacyConstructor));
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       var expectedMessage =
         "The domain object type has a legacy infrastructure constructor for loading (a nonpublic constructor taking a single DataContainer argument). "
@@ -60,9 +60,9 @@ public void NonAbstractType_WithLegacyConstructor ()
     [Test]
     public void AbstractType_WithoutInstantiableAttribute_And_WithoutLegacyConstructor ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(AbstractClassWithoutAttributeAndLegacyCtor));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(AbstractClassWithoutAttributeAndLegacyCtor));
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -70,9 +70,9 @@ public void AbstractType_WithoutInstantiableAttribute_And_WithoutLegacyConstruct
     [Test]
     public void AbstractType_WithoutInstantiableAttribute_And_WithLegacyConstructor ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(AbstractClassWithoutAttributeAndWithLegacyCtor));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(AbstractClassWithoutAttributeAndWithLegacyCtor));
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -80,9 +80,9 @@ public void AbstractType_WithoutInstantiableAttribute_And_WithLegacyConstructor
     [Test]
     public void AbstractType_WithInstantiableAttribute_And_WithoutLegacyConstructor ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(AbstractClassWithAttributeAndWithoutLegacyCtor));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(AbstractClassWithAttributeAndWithoutLegacyCtor));
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -90,9 +90,9 @@ public void AbstractType_WithInstantiableAttribute_And_WithoutLegacyConstructor
     [Test]
     public void AbstractType_WithInstantiableAttribute_And_WithLegacyConstructor ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(AbstractClassWithAttributeAndWithLegacyCtor));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(AbstractClassWithAttributeAndWithLegacyCtor));
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       var expectedMessage =
         "The domain object type has a legacy infrastructure constructor for loading (a nonpublic constructor taking a single DataContainer argument). "
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/DomainObjectTypeIsNotGenericValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/DomainObjectTypeIsNotGenericValidationRuleTest.cs
index b2a581c2fe..916ed38910 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/DomainObjectTypeIsNotGenericValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/DomainObjectTypeIsNotGenericValidationRuleTest.cs
@@ -35,9 +35,9 @@ public void SetUp ()
     [Test]
     public void NoGenericType ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(NonGenericTypeDomainObject));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(NonGenericTypeDomainObject));
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -46,9 +46,9 @@ public void NoGenericType ()
     public void IsGenericType_IsNotDomainObjectBase ()
     {
       var type = typeof(GenericTypeDomainObject<string>);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       var expectedMessage = "Generic domain objects are not supported.\r\n\r\n"
         +"Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Reflection."
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/ForeignKeyIsSupportedForCardinalityOfRelationPropertyValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/ForeignKeyIsSupportedForCardinalityOfRelationPropertyValidationRuleTest.cs
index ecfcf61a5b..93a7649799 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/ForeignKeyIsSupportedForCardinalityOfRelationPropertyValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/ForeignKeyIsSupportedForCardinalityOfRelationPropertyValidationRuleTest.cs
@@ -28,13 +28,13 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Reflection
   public class ForeignKeyIsSupportedForCardinalityOfRelationPropertyValidationRuleTest : ValidationRuleTestBase
   {
     private ForeignKeyIsSupportedForCardinalityOfRelationPropertyValidationRule _validationRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     [SetUp]
     public void SetUp ()
     {
       _validationRule = new ForeignKeyIsSupportedForCardinalityOfRelationPropertyValidationRule();
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ForeignKeyIsSupportedClass));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ForeignKeyIsSupportedClass));
     }
 
     [Test]
@@ -70,7 +70,7 @@ public void RelationDefinitionPropertyInfoIsNotResolved ()
     [Test]
     public void NoReflectionBasedVirtualRelationEndPointDefinition ()
     {
-      var endPointDefinition = new AnonymousRelationEndPointDefinition(_classDefinition);
+      var endPointDefinition = new AnonymousRelationEndPointDefinition(_typeDefinition);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -82,7 +82,7 @@ public void NoReflectionBasedVirtualRelationEndPointDefinition ()
     public void PropertyWithNoDBBidirectionalRelationAttribute ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "PropertyWithNoDbBidirectionalRelationAttribute",
           false,
           PropertyInfoAdapter.Create(typeof(ForeignKeyIsSupportedClass).GetProperty("PropertyWithNoDbBidirectionalRelationAttribute")));
@@ -97,7 +97,7 @@ public void PropertyWithNoDBBidirectionalRelationAttribute ()
     public void NoCollectionProperty_ContainsForeignKeyIsTrue ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "NoCollectionProperty_ContainsForeignKey",
           false,
           PropertyInfoAdapter.Create(typeof(ForeignKeyIsSupportedClass).GetProperty("NoCollectionProperty_ContainsForeignKey")));
@@ -112,7 +112,7 @@ public void NoCollectionProperty_ContainsForeignKeyIsTrue ()
     public void NoCollectionProperty_ContainsForeignKeyIsFalse ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "NoCollectionProperty_ContainsNoForeignKey",
           false,
           PropertyInfoAdapter.Create(typeof(ForeignKeyIsSupportedClass).GetProperty("NoCollectionProperty_ContainsNoForeignKey")));
@@ -127,7 +127,7 @@ public void NoCollectionProperty_ContainsForeignKeyIsFalse ()
     public void DomainObjectCollectionProperty_ContainsForeignKeyIsTrue ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "DomainObjectCollectionProperty_ContainsForeignKey",
           false,
           PropertyInfoAdapter.Create(typeof(ForeignKeyIsSupportedClass).GetProperty("DomainObjectCollectionProperty_ContainsForeignKey")));
@@ -147,7 +147,7 @@ public void DomainObjectCollectionProperty_ContainsForeignKeyIsTrue ()
     public void VirtualCollectionProperty_ContainsForeignKeyIsTrue ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "VirtualCollectionProperty_ContainsForeignKey",
           false,
           PropertyInfoAdapter.Create(typeof(ForeignKeyIsSupportedClass).GetProperty("VirtualCollectionProperty_ContainsForeignKey")));
@@ -167,7 +167,7 @@ public void VirtualCollectionProperty_ContainsForeignKeyIsTrue ()
     public void DomainObjectCollectionProperty_ContainsForeignKeyIsTrue_BothEndPoints ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "DomainObjectCollectionProperty_ContainsForeignKey",
           false,
           PropertyInfoAdapter.Create(typeof(ForeignKeyIsSupportedClass).GetProperty("DomainObjectCollectionProperty_ContainsForeignKey")));
@@ -187,7 +187,7 @@ public void DomainObjectCollectionProperty_ContainsForeignKeyIsTrue_BothEndPoint
     public void VirtualCollectionProperty_ContainsForeignKeyIsTrue_BothEndPoints ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "VirtualCollectionProperty_ContainsForeignKey",
           false,
           PropertyInfoAdapter.Create(typeof(ForeignKeyIsSupportedClass).GetProperty("VirtualCollectionProperty_ContainsForeignKey")));
@@ -207,7 +207,7 @@ public void VirtualCollectionProperty_ContainsForeignKeyIsTrue_BothEndPoints ()
     public void DomainObjectCollectionProperty_ContainsForeignKeyIsFalse ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "DomainObjectCollectionProperty_ContainsNoForeignKey",
           false,
           PropertyInfoAdapter.Create(typeof(ForeignKeyIsSupportedClass).GetProperty("DomainObjectCollectionProperty_ContainsNoForeignKey")));
@@ -222,7 +222,7 @@ public void DomainObjectCollectionProperty_ContainsForeignKeyIsFalse ()
     public void VirtualCollectionProperty_ContainsForeignKeyIsFalse ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "VirtualCollectionProperty_ContainsNoForeignKey",
           false,
           PropertyInfoAdapter.Create(typeof(ForeignKeyIsSupportedClass).GetProperty("VirtualCollectionProperty_ContainsNoForeignKey")));
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/InheritanceHierarchyFollowsClassHierarchyValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/InheritanceHierarchyFollowsClassHierarchyValidationRuleTest.cs
index bcbce02101..de52918b36 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/InheritanceHierarchyFollowsClassHierarchyValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/InheritanceHierarchyFollowsClassHierarchyValidationRuleTest.cs
@@ -25,6 +25,8 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Reflection
   [TestFixture]
   public class InheritanceHierarchyFollowsClassHierarchyValidationRuleTest : ValidationRuleTestBase
   {
+    // TODO R2I extend for interfaces
+    // TODO R2I also handle InterfaceDefinitionWithUnresolvedType
     private InheritanceHierarchyFollowsClassHierarchyValidationRule _validationRule;
 
     [SetUp]
@@ -36,36 +38,35 @@ public void SetUp ()
     [Test]
     public void ClassDefinitionWithoutBaseClass ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(BaseOfBaseValidationDomainObjectClass));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(BaseOfBaseValidationDomainObjectClass));
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
 
     [Test]
-    public void ClassDefinitionWithBaseClass_ClassTypeIsDerivedFromBaseClassType ()
+    public void ClassDefinitionWithBaseClass_TypeIsDerivedFromBaseType ()
     {
       var baseType = typeof(BaseOfBaseValidationDomainObjectClass);
       var baseClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: baseType);
       var derivedType = typeof(BaseValidationDomainObjectClass);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: derivedType, baseClass: baseClassDefinition);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: derivedType, baseClass: baseClassDefinition);
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
 
     [Test]
-    public void ClassDefinitionWithBaseClass_ClassTypeIsNotDerivedFromBaseClassType ()
+    public void ClassDefinitionWithBaseClass_TypeIsNotDerivedFromBaseType ()
     {
       var baseType = typeof(BaseOfBaseValidationDomainObjectClass);
       var baseClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition("Base", baseType);
-      var derivedType = typeof(BaseValidationDomainObjectClass);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(id: "Derived", classType: derivedType, baseClass: baseClassDefinition);
-      PrivateInvoke.SetNonPublicField(classDefinition, "_classType", typeof(ClassOutOfInheritanceHierarchy));
+      var derivedType = typeof(ClassOutOfInheritanceHierarchy);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(id: "Derived", classType: derivedType, baseClass: baseClassDefinition);
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       Assert.That(validationResult.IsValid, Is.False);
       var expectedMessage =
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/MappingAttributesAreOnlyAppliedOnOriginalPropertyDeclarationsValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/MappingAttributesAreOnlyAppliedOnOriginalPropertyDeclarationsValidationRuleTest.cs
index daeacc07e0..453282a89e 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/MappingAttributesAreOnlyAppliedOnOriginalPropertyDeclarationsValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/MappingAttributesAreOnlyAppliedOnOriginalPropertyDeclarationsValidationRuleTest.cs
@@ -41,24 +41,26 @@ public void SetUp ()
     }
 
     [Test]
-    public void ClassDefinitionWithUnresolvedClassType ()
+    public void ClassDefinitionWithUnresolvedType ()
     {
       var type = typeof(BaseMappingAttributesClass);
-      var classDefinition = new ClassDefinitionWithUnresolvedClassType(
-          "Test", type, true, null, new Mock<IPersistentMixinFinder>().Object, new Mock<IDomainObjectCreator>().Object);
+      var classDefinition = new ClassDefinitionWithUnresolvedType(
+          "Test", type, true, null, Enumerable.Empty<InterfaceDefinition>(), new Mock<IPersistentMixinFinder>().Object, new Mock<IDomainObjectCreator>().Object);
       Assert.That(
           () => _validationRule.Validate(classDefinition),
           Throws.InvalidOperationException
-              .With.Message.EqualTo("Class type of 'Test' is not resolved."));
+              .With.Message.EqualTo(
+                  "Type 'Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Reflection."
+                  + "MappingAttributesAreOnlyAppliedOnOriginalPropertyDeclarationsValidationRule.BaseMappingAttributesClass' is not resolved."));
     }
 
     [Test]
     public void OriginalPropertyDeclaration ()
     {
       var type = typeof(BaseMappingAttributesClass);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: type);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: type);
 
-      var validationResult = _validationRule.Validate(classDefinition).First();
+      var validationResult = _validationRule.Validate(typeDefinition).First();
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -67,9 +69,9 @@ public void OriginalPropertyDeclaration ()
     public void NonOriginalPropertiesDeclarationWithMappingAttribute_NoInheritanceRoot ()
     {
       var type = typeof(DerivedClassWithMappingAttribute);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: type);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: type);
 
-      var validationResult = _validationRule.Validate(classDefinition).Where(r=>!r.IsValid).ToArray();
+      var validationResult = _validationRule.Validate(typeDefinition).Where(r=>!r.IsValid).ToArray();
 
       var expectedMessage1 =
         "The 'StorageClassNoneAttribute' is a mapping attribute and may only be applied at the property's base definition.\r\n\r\n"
@@ -88,9 +90,9 @@ public void NonOriginalPropertiesDeclarationWithMappingAttribute_NoInheritanceRo
     public void NonOriginalPropertiesDeclarationWithMappingAttribute_InheritanceRoot ()
     {
       var type = typeof(InheritanceRootDerivedMappingAttributesClass);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: type);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: type);
 
-      var validationResult = _validationRule.Validate(classDefinition).Where(r => !r.IsValid).ToArray();
+      var validationResult = _validationRule.Validate(typeDefinition).Where(r => !r.IsValid).ToArray();
 
       var expectedMessage1 =
         "The 'StorageClassNoneAttribute' is a mapping attribute and may only be applied at the property's base definition.\r\n\r\n"
@@ -109,9 +111,9 @@ public void NonOriginalPropertiesDeclarationWithMappingAttribute_InheritanceRoot
     [Ignore("TODO RM-4449: Utilities.ReflectionUtility.IsOriginalDeclaration does not work for Mixins")]
     public void NonOriginalPropertiesDeclarationWithMappingAttributeOnMixin_NoInheritanceRoot ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassUsingMixinPropertiesNoInheritanceRoot));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassUsingMixinPropertiesNoInheritanceRoot));
 
-      var validationResult = _validationRule.Validate(classDefinition).ToArray();
+      var validationResult = _validationRule.Validate(typeDefinition).ToArray();
 
       var expectedMessage1 =
         "The 'StorageClassNoneAttribute' is a mapping attribute and may only be applied at the property's base definition.\r\n\r\n"
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/MappingAttributesAreSupportedForPropertyTypeValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/MappingAttributesAreSupportedForPropertyTypeValidationRuleTest.cs
index fac28cca7e..a74bd4617e 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/MappingAttributesAreSupportedForPropertyTypeValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/MappingAttributesAreSupportedForPropertyTypeValidationRuleTest.cs
@@ -27,7 +27,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Reflection
   public class MappingAttributesAreSupportedForPropertyTypeValidationRuleTest : ValidationRuleTestBase
   {
     private MappingAttributesAreSupportedForPropertyTypeValidationRule _validtionRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
     private Type _validType;
     private Type _invalidType;
 
@@ -37,17 +37,17 @@ public void SetUp ()
       _validtionRule = new MappingAttributesAreSupportedForPropertyTypeValidationRule();
       _validType = typeof(ClassWithValidPropertyAttributes);
       _invalidType = typeof(ClassWithInvalidPropertyAttributes);
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: _validType);
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties(classType: _validType);
     }
 
     [Test]
     public void ValidPropertyWithStringPropertyAttribute ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _validType, "StringProperty");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _validType, "StringProperty");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -55,11 +55,11 @@ public void ValidPropertyWithStringPropertyAttribute ()
     [Test]
     public void InvalidPropertyWithStringPropertyAttribute ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _invalidType, "IntPropertyWithStringPropertyAttribute");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _invalidType, "IntPropertyWithStringPropertyAttribute");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, false,
         "The 'StringPropertyAttribute' may be only applied to properties of type 'String'.\r\n\r\n"
@@ -71,11 +71,11 @@ public void InvalidPropertyWithStringPropertyAttribute ()
     [Test]
     public void ValidPropertyWithBinaryPropertyAttribute ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _validType, "BinaryProperty");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _validType, "BinaryProperty");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -83,11 +83,11 @@ public void ValidPropertyWithBinaryPropertyAttribute ()
     [Test]
     public void InvalidPropertyWithBinaryPropertyAttribute ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _invalidType, "BoolPropertyWithBinaryPropertyAttribute");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _invalidType, "BoolPropertyWithBinaryPropertyAttribute");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, false, "The 'BinaryPropertyAttribute' may be only applied to properties of type 'Byte[]'.\r\n\r\n"
         + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Reflection."
@@ -98,11 +98,11 @@ public void InvalidPropertyWithBinaryPropertyAttribute ()
     [Test]
     public void ValidPropertyWithExtensibleEnumPropertyAttribute ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _validType, "ExtensibleEnumProperty");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _validType, "ExtensibleEnumProperty");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -110,11 +110,11 @@ public void ValidPropertyWithExtensibleEnumPropertyAttribute ()
     [Test]
     public void InvalidPropertyWithExtensibleEnumPropertyAttribute ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _invalidType, "StringPropertyWithExtensibleEnumPropertyAttribute");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _invalidType, "StringPropertyWithExtensibleEnumPropertyAttribute");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, false, "The 'ExtensibleEnumPropertyAttribute' may be only applied to properties of type 'IExtensibleEnum'.\r\n\r\n"
         + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Reflection."
@@ -125,11 +125,11 @@ public void InvalidPropertyWithExtensibleEnumPropertyAttribute ()
     [Test]
     public void ValidPropertyWithMandatoryPropertyAttribute ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _validType, "MandatoryProperty");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _validType, "MandatoryProperty");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -137,11 +137,11 @@ public void ValidPropertyWithMandatoryPropertyAttribute ()
     [Test]
     public void InvalidPropertyWithMandatoryPropertyAttribute ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _invalidType, "StringPropertyWithMandatoryPropertyAttribute");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _invalidType, "StringPropertyWithMandatoryPropertyAttribute");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, false,
         "The 'MandatoryAttribute' may be only applied to properties assignable to types 'DomainObject', 'ObjectList`1', or 'IObjectList`1'.\r\n\r\n"
@@ -154,13 +154,13 @@ public void InvalidPropertyWithMandatoryPropertyAttribute ()
     public void ValidDomainObjectPropertyWithBidirectionalRelationAttribute ()
     {
       var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(
-          _classDefinition,
+          _typeDefinition,
           _validType,
           "DomainObjectBidirectionalRelationProperty");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -169,13 +169,13 @@ public void ValidDomainObjectPropertyWithBidirectionalRelationAttribute ()
     public void ValidDomainObjectCollectionPropertyWithBidirectionalRelationAttribute ()
     {
       var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(
-          _classDefinition,
+          _typeDefinition,
           _validType,
           "DomainObjectCollectionBidirectionalRelationProperty");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -184,13 +184,13 @@ public void ValidDomainObjectCollectionPropertyWithBidirectionalRelationAttribut
     public void ValidVirtualCollectionPropertyWithBidirectionalRelationAttribute ()
     {
       var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(
-          _classDefinition,
+          _typeDefinition,
           _validType,
           "VirtualCollectionBidirectionalRelationProperty");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -198,11 +198,11 @@ public void ValidVirtualCollectionPropertyWithBidirectionalRelationAttribute ()
     [Test]
     public void InvalidPropertyWithBidirectionalRelationAttribute ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _invalidType, "StringPropertyWithBidirectionalRelationAttribute");
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _invalidType, "StringPropertyWithBidirectionalRelationAttribute");
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition);
+      var validationResult = _validtionRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, false,
         "The 'DBBidirectionalRelationAttribute' may be only applied to properties assignable to types 'DomainObject', 'ObjectList`1', or 'IObjectList`1'.\r\n\r\n"
@@ -214,14 +214,14 @@ public void InvalidPropertyWithBidirectionalRelationAttribute ()
     [Test]
     public void SeveralInvalidProperties ()
     {
-      var propertyDefinition1 = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _invalidType, "StringPropertyWithMandatoryPropertyAttribute");
-      var propertyDefinition2 = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _invalidType, "StringPropertyWithExtensibleEnumPropertyAttribute");
-      var propertyDefinition3 = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_classDefinition, _invalidType, "BoolPropertyWithBinaryPropertyAttribute");
+      var propertyDefinition1 = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _invalidType, "StringPropertyWithMandatoryPropertyAttribute");
+      var propertyDefinition2 = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _invalidType, "StringPropertyWithExtensibleEnumPropertyAttribute");
+      var propertyDefinition3 = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(_typeDefinition, _invalidType, "BoolPropertyWithBinaryPropertyAttribute");
 
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition1, propertyDefinition2, propertyDefinition3}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition1, propertyDefinition2, propertyDefinition3}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validtionRule.Validate(_classDefinition).ToArray();
+      var validationResult = _validtionRule.Validate(_typeDefinition).ToArray();
 
       var expectedMessage1 = "The 'MandatoryAttribute' may be only applied to properties assignable to types 'DomainObject', 'ObjectList`1', or 'IObjectList`1'.\r\n\r\n"
         + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.Reflection."
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointNamesAreConsistentValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointNamesAreConsistentValidationRuleTest.cs
index b72f005aee..9d7e5aac10 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointNamesAreConsistentValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointNamesAreConsistentValidationRuleTest.cs
@@ -27,27 +27,27 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Reflection
   public class RelationEndPointNamesAreConsistentValidationRuleTest : ValidationRuleTestBase
   {
     private RelationEndPointNamesAreConsistentValidationRule _validationRule;
-    private ClassDefinition _classDefinition1;
-    private ClassDefinition _classDefinition2;
+    private TypeDefinition _typeDefinition1;
+    private TypeDefinition _typeDefinition2;
 
     [SetUp]
     public void SetUp ()
     {
       _validationRule = new RelationEndPointNamesAreConsistentValidationRule();
-      _classDefinition1 = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass1));
-      _classDefinition2 = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass2));
+      _typeDefinition1 = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass1));
+      _typeDefinition2 = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass2));
     }
 
     [Test]
     public void ValidRelation ()
     {
       var endPointDefinition1 = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition1,
+          _typeDefinition1,
           "RelationProperty2",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass1).GetProperty("RelationProperty2")));
       var endPointDefinition2 = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition2,
+          _typeDefinition2,
           "RelationProperty2",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass2).GetProperty("RelationProperty2")));
@@ -61,9 +61,9 @@ public void ValidRelation ()
     [Test]
     public void LeftEndPointIsAnonymous ()
     {
-      var endPointDefinition1 = new AnonymousRelationEndPointDefinition(_classDefinition1);
+      var endPointDefinition1 = new AnonymousRelationEndPointDefinition(_typeDefinition1);
       var endPointDefinition2 = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition2,
+          _typeDefinition2,
           "RelationProperty2",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass2).GetProperty("RelationProperty2")));
@@ -78,11 +78,11 @@ public void LeftEndPointIsAnonymous ()
     public void RightEndPointIsAnonymous ()
     {
       var endPointDefinition1 = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition1,
+          _typeDefinition1,
           "RelationProperty2",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass1).GetProperty("RelationProperty2")));
-      var endPointDefinition2 = new AnonymousRelationEndPointDefinition(_classDefinition2);
+      var endPointDefinition2 = new AnonymousRelationEndPointDefinition(_typeDefinition2);
 
       var relationDefinition = CreateRelationDefinitionAndSetBackReferences("Test", endPointDefinition1, endPointDefinition2);
 
@@ -94,12 +94,12 @@ public void RightEndPointIsAnonymous ()
     public void OppositeRelationPropertyHasNoBidirectionalRelationAttributeDefined ()
     {
       var endPointDefinition1 = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition1,
+          _typeDefinition1,
           "RelationProperty1",
           false,
          PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass1).GetProperty("RelationProperty1")));
       var endPointDefinition2 = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition2,
+          _typeDefinition2,
           "RelationPopertyWithoutBidirectionalRelationAttribute",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass2).GetProperty("RelationPopertyWithoutBidirectionalRelationAttribute")));
@@ -121,12 +121,12 @@ public void OppositeRelationPropertyHasNoBidirectionalRelationAttributeDefined (
     public void OppositeRelationPropertyNameDoesNotMatch ()
     {
       var endPointDefinition1 = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition1,
+          _typeDefinition1,
           "RelationProperty3",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass1).GetProperty("RelationProperty3")));
       var endPointDefinition2 = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition2,
+          _typeDefinition2,
           "RelationPopertyWithNonMatchingPropertyName",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass2).GetProperty("RelationPopertyWithNonMatchingPropertyName")));
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointPropertyTypeIsSupportedValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointPropertyTypeIsSupportedValidationRuleTest.cs
index 5a029c3e20..10138c0807 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointPropertyTypeIsSupportedValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointPropertyTypeIsSupportedValidationRuleTest.cs
@@ -27,17 +27,17 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation.Reflection
   public class RelationEndPointPropertyTypeIsSupportedValidationRuleTest : ValidationRuleTestBase
   {
     private RelationEndPointPropertyTypeIsSupportedValidationRule _validationRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
     private IRelationEndPointDefinition _validEndPointDefinition;
 
     [SetUp]
     public void SetUp ()
     {
       _validationRule = new RelationEndPointPropertyTypeIsSupportedValidationRule();
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(RelationEndPointPropertyClass));
 
       _validEndPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "DomainObjectPropertyWithBidirectionalAttribute",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass).GetProperty("DomainObjectPropertyWithBidirectionalAttribute")));
@@ -46,7 +46,7 @@ public void SetUp ()
     [Test]
     public void NoReflectionBasedVirtualRelationEndPointDefinition ()
     {
-      var endPointDefinition = new AnonymousRelationEndPointDefinition(_classDefinition);
+      var endPointDefinition = new AnonymousRelationEndPointDefinition(_typeDefinition);
       var relationDefinition = new RelationDefinition("Test", endPointDefinition, endPointDefinition);
 
       var validationResult = _validationRule.Validate(relationDefinition);
@@ -58,7 +58,7 @@ public void NoReflectionBasedVirtualRelationEndPointDefinition ()
     public void NoBidirectionalRelation_LeftPropertyTypeNoDomainObject ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "PropertyWithoutBidirectionalAttribute",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass).GetProperty("PropertyWithoutBidirectionalAttribute")));
@@ -78,7 +78,7 @@ public void NoBidirectionalRelation_LeftPropertyTypeNoDomainObject ()
     public void NoBidirectionalRelation_RightPropertyTypeNoDomainObject ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "PropertyWithoutBidirectionalAttribute",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass).GetProperty("PropertyWithoutBidirectionalAttribute")));
@@ -98,7 +98,7 @@ public void NoBidirectionalRelation_RightPropertyTypeNoDomainObject ()
     public void NoBidirectionalRelation_PropertyTypeDomainObject ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "DomainObjectPropertyWithoutBidirectionalAttribute",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass).GetProperty("DomainObjectPropertyWithoutBidirectionalAttribute")));
@@ -113,7 +113,7 @@ public void NoBidirectionalRelation_PropertyTypeDomainObject ()
     public void BidirectionalRelation_PropertyTypeDomainObject ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "DomainObjectPropertyWithBidirectionalAttribute",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass).GetProperty("DomainObjectPropertyWithBidirectionalAttribute")));
@@ -128,7 +128,7 @@ public void BidirectionalRelation_PropertyTypeDomainObject ()
     public void BidirectionalRelation_PropertyTypeNoDomainObject ()
     {
       var endPointDefinition = new VirtualObjectRelationEndPointDefinition(
-          _classDefinition,
+          _typeDefinition,
           "PropertyWithBidirectionalAttribute",
           false,
           PropertyInfoAdapter.Create(typeof(RelationEndPointPropertyClass).GetProperty("PropertyWithBidirectionalAttribute")));
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointTypesAreConsistentValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointTypesAreConsistentValidationRuleTest.cs
index 4922a4b1c7..aa3366f8cd 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointTypesAreConsistentValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/RelationEndPointTypesAreConsistentValidationRuleTest.cs
@@ -29,8 +29,8 @@ public class RelationEndPointTypesAreConsistentValidationRuleTest : ValidationRu
     private RelationEndPointTypesAreConsistentValidationRule _validationRule;
     private ClassDefinition _baseClassDefinition1;
     private ClassDefinition _baseClassDefinition2;
-    private ClassDefinition _derivedClassDefinition1;
-    private ClassDefinition _derivedClassDefinition2;
+    private TypeDefinition _derivedClassDefinition1;
+    private TypeDefinition _derivedClassDefinition2;
 
     [SetUp]
     public void SetUp ()
@@ -38,11 +38,11 @@ public void SetUp ()
       _validationRule = new RelationEndPointTypesAreConsistentValidationRule();
       _baseClassDefinition1 = ClassDefinitionObjectMother.CreateClassDefinition("BaseRelationEndPointPropertyClass1", typeof(BaseRelationEndPointPropertyClass1));
       _baseClassDefinition2 = ClassDefinitionObjectMother.CreateClassDefinition("BaseRelationEndPointPropertyClass2", typeof(BaseRelationEndPointPropertyClass2));
-      _derivedClassDefinition1 = ClassDefinitionObjectMother.CreateClassDefinition(
+      _derivedClassDefinition1 = TypeDefinitionObjectMother.CreateClassDefinition(
           "DerivedRelationEndPointPropertyClass1",
           typeof(DerivedRelationEndPointPropertyClass1),
           baseClass: _baseClassDefinition1);
-      _derivedClassDefinition2 = ClassDefinitionObjectMother.CreateClassDefinition(
+      _derivedClassDefinition2 = TypeDefinitionObjectMother.CreateClassDefinition(
           "DerivedRelationEndPointPropertyClass2",
           typeof(DerivedRelationEndPointPropertyClass2),
           baseClass: _baseClassDefinition2);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/StorageGroupAttributeIsOnlyDefinedOncePerInheritanceHierarchyValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/StorageGroupAttributeIsOnlyDefinedOncePerInheritanceHierarchyValidationRuleTest.cs
index d696f39691..1af089dd9e 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/StorageGroupAttributeIsOnlyDefinedOncePerInheritanceHierarchyValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/Reflection/StorageGroupAttributeIsOnlyDefinedOncePerInheritanceHierarchyValidationRuleTest.cs
@@ -36,9 +36,9 @@ public void SetUp ()
     public void NotInheritanceRoot ()
     {
       var type = typeof(DerivedClassWithoutStorageGroupAttribute);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
 
-      var validationResult = _validationRule.Validate(classDefinition);
+      var validationResult = _validationRule.Validate(typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -47,7 +47,7 @@ public void NotInheritanceRoot ()
     public void InheritanceRoot_WithoutStorageGroupAttribute ()
     {
       var type = typeof(BaseClassWithoutStorageGroupAttribute);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
+      var classDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
 
       var validationResult = _validationRule.Validate(classDefinition);
 
@@ -58,7 +58,7 @@ public void InheritanceRoot_WithoutStorageGroupAttribute ()
     public void InheritanceRoot_WithStorageGroupAttribute_And_WithoutStorageGroupAttributeOnBaseClass ()
     {
       var type = typeof(BaseClassWithStorageGroupAttribute);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
+      var classDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
 
       var validationResult = _validationRule.Validate(classDefinition);
 
@@ -68,7 +68,7 @@ public void InheritanceRoot_WithStorageGroupAttribute_And_WithoutStorageGroupAtt
     [Test]
     public void InheritanceRoot_WithoutBaseClass ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(object));
+      var classDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(object));
 
       var validationResult = _validationRule.Validate(classDefinition);
 
@@ -79,7 +79,7 @@ public void InheritanceRoot_WithoutBaseClass ()
     public void InheritanceRoot_WithStorageGroupAttribute_And_WithStorageGroupAttributeOnBaseClass ()
     {
       var type = typeof(DerivedClassWithStorageGroupAttribute);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
+      var classDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(type);
 
       var validationResult = _validationRule.Validate(classDefinition);
 
@@ -94,7 +94,7 @@ public void InheritanceRoot_WithStorageGroupAttribute_And_WithStorageGroupAttrib
     public void InheritanceRoot_WithStorageGroupAttribute_And_WithStorageGroupAttributeOnBaseClass_And_BaseClassIsNotDomainObject ()
     {
       var type = typeof(DerivedClassWithStorageGroupAttributeAndNonDomainObjectBaseTypeWithStorageGroupAttribute);
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: type);
+      var classDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: type);
 
       var validationResult = _validationRule.Validate(classDefinition);
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/TypeDefinitionValidatorTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/TypeDefinitionValidatorTest.cs
new file mode 100644
index 0000000000..86064d7f4f
--- /dev/null
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/Validation/TypeDefinitionValidatorTest.cs
@@ -0,0 +1,136 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using System.Linq;
+using Moq;
+using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
+using Remotion.Data.DomainObjects.Mapping.Validation;
+using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation;
+
+namespace Remotion.Data.DomainObjects.UnitTests.Mapping.Validation
+{
+  [TestFixture]
+  public class TypeDefinitionValidatorTest
+  {
+    private TypeDefinition _typeDefinition1;
+    private TypeDefinition _typeDefinition2;
+    private TypeDefinition _typeDefinition3;
+    private MappingValidationResult _fakeValidMappingValidationResult;
+    private MappingValidationResult _fakeInvalidMappingValidationResult;
+    private Mock<ITypeDefinitionValidationRule> _validationRuleMock1;
+    private Mock<ITypeDefinitionValidationRule> _validationRuleMock2;
+    private Mock<ITypeDefinitionValidationRule> _validationRuleMock3;
+
+    [SetUp]
+    public void SetUp ()
+    {
+      _typeDefinition1 = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
+      _typeDefinition2 = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
+      _typeDefinition3 = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass));
+
+      _validationRuleMock1 = new Mock<ITypeDefinitionValidationRule>(MockBehavior.Strict);
+      _validationRuleMock2 = new Mock<ITypeDefinitionValidationRule>(MockBehavior.Strict);
+      _validationRuleMock3 = new Mock<ITypeDefinitionValidationRule>(MockBehavior.Strict);
+
+      _fakeValidMappingValidationResult = MappingValidationResult.CreateValidResult();
+      _fakeInvalidMappingValidationResult = MappingValidationResult.CreateInvalidResult("Test");
+    }
+
+    [Test]
+    public void ValidateWithOneRuleAndClassDefinition_ValidResult ()
+    {
+      var validator = new TypeDefinitionValidator(_validationRuleMock1.Object);
+
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(_fakeValidMappingValidationResult).Verifiable();
+
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1 }).ToArray();
+
+      _validationRuleMock1.Verify();
+      Assert.That(validator.ValidationRules.Count, Is.EqualTo(1));
+      Assert.That(mappingValidationResults.Length, Is.EqualTo(0));
+    }
+
+    [Test]
+    public void ValidateWithOneRuleAndClassDefinition_InvalidResult ()
+    {
+      var validator = new TypeDefinitionValidator(_validationRuleMock1.Object);
+
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
+
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1 }).ToArray();
+
+      _validationRuleMock1.Verify();
+      Assert.That(validator.ValidationRules.Count, Is.EqualTo(1));
+      Assert.That(mappingValidationResults.Length, Is.EqualTo(1));
+      Assert.That(mappingValidationResults[0], Is.SameAs(_fakeInvalidMappingValidationResult));
+    }
+
+    [Test]
+    public void ValidateWithSeveralRulesAndClassDefinitions_ValidResult ()
+    {
+      var validator = new TypeDefinitionValidator(_validationRuleMock1.Object, _validationRuleMock2.Object, _validationRuleMock3.Object);
+
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(_fakeValidMappingValidationResult).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition2)).Returns(_fakeValidMappingValidationResult).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition3)).Returns(_fakeValidMappingValidationResult).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition1)).Returns(_fakeValidMappingValidationResult).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition2)).Returns(_fakeValidMappingValidationResult).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition3)).Returns(_fakeValidMappingValidationResult).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition1)).Returns(_fakeValidMappingValidationResult).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition2)).Returns(_fakeValidMappingValidationResult).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition3)).Returns(_fakeValidMappingValidationResult).Verifiable();
+
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1, _typeDefinition2, _typeDefinition3 }).ToArray();
+
+      _validationRuleMock1.Verify();
+      Assert.That(validator.ValidationRules.Count, Is.EqualTo(3));
+      Assert.That(mappingValidationResults.Length, Is.EqualTo(0));
+    }
+
+    [Test]
+    public void ValidateWithSeveralRulesAndClassDefinitions_InvalidResult ()
+    {
+      var validator = new TypeDefinitionValidator(_validationRuleMock1.Object, _validationRuleMock2.Object, _validationRuleMock3.Object);
+
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition1)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition2)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
+      _validationRuleMock1.Setup(mock => mock.Validate(_typeDefinition3)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition1)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition2)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
+      _validationRuleMock2.Setup(mock => mock.Validate(_typeDefinition3)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition1)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition2)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
+      _validationRuleMock3.Setup(mock => mock.Validate(_typeDefinition3)).Returns(_fakeInvalidMappingValidationResult).Verifiable();
+
+      var mappingValidationResults = validator.Validate(new[] { _typeDefinition1, _typeDefinition2, _typeDefinition3 }).ToArray();
+
+      _validationRuleMock1.Verify();
+      Assert.That(validator.ValidationRules.Count, Is.EqualTo(3));
+      Assert.That(mappingValidationResults.Length, Is.EqualTo(9));
+      Assert.That(mappingValidationResults[0], Is.SameAs(_fakeInvalidMappingValidationResult));
+      Assert.That(mappingValidationResults[1], Is.SameAs(_fakeInvalidMappingValidationResult));
+      Assert.That(mappingValidationResults[2], Is.SameAs(_fakeInvalidMappingValidationResult));
+      Assert.That(mappingValidationResults[3], Is.SameAs(_fakeInvalidMappingValidationResult));
+      Assert.That(mappingValidationResults[4], Is.SameAs(_fakeInvalidMappingValidationResult));
+      Assert.That(mappingValidationResults[5], Is.SameAs(_fakeInvalidMappingValidationResult));
+      Assert.That(mappingValidationResults[6], Is.SameAs(_fakeInvalidMappingValidationResult));
+      Assert.That(mappingValidationResults[7], Is.SameAs(_fakeInvalidMappingValidationResult));
+      Assert.That(mappingValidationResults[8], Is.SameAs(_fakeInvalidMappingValidationResult));
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualCollectionRelationEndPointDefinitionFactory.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualCollectionRelationEndPointDefinitionFactory.cs
index 123ca3e115..bd5f841237 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualCollectionRelationEndPointDefinitionFactory.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualCollectionRelationEndPointDefinitionFactory.cs
@@ -25,7 +25,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   public static class VirtualCollectionRelationEndPointDefinitionFactory
   {
     public static VirtualCollectionRelationEndPointDefinition Create (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         bool isMandatory,
         Type propertyType,
@@ -34,19 +34,19 @@ public static VirtualCollectionRelationEndPointDefinition Create (
       var propertyInformationStub = new Mock<IPropertyInformation>();
       propertyInformationStub.Setup(stub => stub.Name).Returns(propertyName);
       propertyInformationStub.Setup(stub => stub.PropertyType).Returns(propertyType);
-      propertyInformationStub.Setup(stub => stub.DeclaringType).Returns(TypeAdapter.Create(classDefinition.ClassType));
+      propertyInformationStub.Setup(stub => stub.DeclaringType).Returns(TypeAdapter.Create(typeDefinition.Type));
 
       return new VirtualCollectionRelationEndPointDefinition(
-          classDefinition, propertyName, isMandatory, sortExpressionDefinition, propertyInformationStub.Object);
+          typeDefinition, propertyName, isMandatory, sortExpressionDefinition, propertyInformationStub.Object);
     }
 
     public static VirtualCollectionRelationEndPointDefinition Create (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         bool isMandatory,
         Type propertyType)
     {
-      return Create(classDefinition, propertyName, isMandatory, propertyType, new Lazy<SortExpressionDefinition>(() => null));
+      return Create(typeDefinition, propertyName, isMandatory, propertyType, new Lazy<SortExpressionDefinition>(() => null));
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualCollectionRelationEndPointDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualCollectionRelationEndPointDefinitionTest.cs
index 4772b2bd16..64d5d8d7d9 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualCollectionRelationEndPointDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualCollectionRelationEndPointDefinitionTest.cs
@@ -30,9 +30,9 @@ public class VirtualCollectionRelationEndPointDefinitionTest : MappingReflection
     [Test]
     public void InitializeWithPropertyType ()
     {
-      var classDefinition = CreateProductDefinition_WithEmptyMembers_AndDerivedClasses();
+      var typeDefinition = CreateProductDefinition_WithEmptyMembers_AndDerivedClasses();
       var endPoint = VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          classDefinition,
+          typeDefinition,
           "VirtualEndPoint",
           true,
           typeof(IObjectList<ProductReview>));
@@ -72,9 +72,9 @@ public void SetRelationDefinition ()
     [Test]
     public void GetSortExpression_Null ()
     {
-      var classDefinition = CreateProductDefinition_WithEmptyMembers_AndDerivedClasses();
+      var typeDefinition = CreateProductDefinition_WithEmptyMembers_AndDerivedClasses();
       var endPoint = VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          classDefinition,
+          typeDefinition,
           "Reviews",
           false,
           typeof(IObjectList<ProductReview>));
@@ -85,14 +85,14 @@ public void GetSortExpression_Null ()
     [Test]
     public void GetSortExpression_NonNull ()
     {
-      var productReviewClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(ProductReview));
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(productReviewClassDefinition, typeof(ProductReview), "CreatedAt");
+      var productReviewTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(ProductReview));
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(productReviewTypeDefinition, typeof(ProductReview), "CreatedAt");
       var sortExpressionDefinition = new SortExpressionDefinition(new[] { SortExpressionDefinitionObjectMother.CreateSortedPropertyDescending(propertyDefinition) });
 
-      var classDefinition = CreateProductDefinition_WithEmptyMembers_AndDerivedClasses();
+      var typeDefinition = CreateProductDefinition_WithEmptyMembers_AndDerivedClasses();
 
       var endPoint = VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          classDefinition,
+          typeDefinition,
           "Reviews",
           false,
           typeof(IObjectList<ProductReview>),
@@ -104,25 +104,25 @@ public void GetSortExpression_NonNull ()
     [Test]
     public void PropertyInfo ()
     {
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Product));
+      var typeDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Product));
       var relationEndPointDefinition =
-          (VirtualCollectionRelationEndPointDefinition)classDefinition.GetRelationEndPointDefinition(typeof(Product) + ".Reviews");
+          (VirtualCollectionRelationEndPointDefinition)typeDefinition.GetRelationEndPointDefinition(typeof(Product) + ".Reviews");
       Assert.That(relationEndPointDefinition.PropertyInfo, Is.EqualTo(PropertyInfoAdapter.Create(typeof(Product).GetProperty("Reviews"))));
     }
 
-    private ClassDefinition CreateProductDefinition_WithEmptyMembers_AndDerivedClasses ()
+    private TypeDefinition CreateProductDefinition_WithEmptyMembers_AndDerivedClasses ()
     {
-      return ClassDefinitionObjectMother.CreateClassDefinition_WithEmptyMembers_AndDerivedClasses("Product", classType: typeof(Product));
+      return TypeDefinitionObjectMother.CreateClassDefinition_WithEmptyMembers_AndDerivedClasses("Product", classType: typeof(Product));
     }
 
     private VirtualCollectionRelationEndPointDefinition CreateReviewsEndPointDefinition ()
     {
-      var productClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Product));
-      var productReviewClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(ProductReview));
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(productReviewClassDefinition, typeof(ProductReview), "CreatedAt");
+      var productTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Product));
+      var productReviewTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(ProductReview));
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(productReviewTypeDefinition, typeof(ProductReview), "CreatedAt");
       var sortExpressionDefinition = new SortExpressionDefinition(new[] { SortExpressionDefinitionObjectMother.CreateSortedPropertyDescending(propertyDefinition) });
       return VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          productClassDefinition,
+          productTypeDefinition,
           "Reviews",
           false,
           typeof(IObjectList<ProductReview>),
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualObjectRelationEndPointDefinitionFactory.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualObjectRelationEndPointDefinitionFactory.cs
index 12ec248728..547d9c7579 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualObjectRelationEndPointDefinitionFactory.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualObjectRelationEndPointDefinitionFactory.cs
@@ -25,7 +25,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   public static class VirtualObjectRelationEndPointDefinitionFactory
   {
     public static VirtualObjectRelationEndPointDefinition Create (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         bool isMandatory,
         Type propertyType)
@@ -33,20 +33,20 @@ public static VirtualObjectRelationEndPointDefinition Create (
       var propertyInformationStub = new Mock<IPropertyInformation>();
       propertyInformationStub.Setup(stub => stub.Name).Returns(propertyName);
       propertyInformationStub.Setup(stub => stub.PropertyType).Returns(propertyType);
-      propertyInformationStub.Setup(stub => stub.DeclaringType).Returns(TypeAdapter.Create(classDefinition.ClassType));
+      propertyInformationStub.Setup(stub => stub.DeclaringType).Returns(TypeAdapter.Create(typeDefinition.Type));
 
       return new VirtualObjectRelationEndPointDefinition(
-          classDefinition, propertyName, isMandatory, propertyInformationStub.Object);
+          typeDefinition, propertyName, isMandatory, propertyInformationStub.Object);
     }
 
     public static VirtualObjectRelationEndPointDefinition Create (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         bool isMandatory,
         Type propertyType,
         string sortExpression)
     {
-      var relationEndPointDefinition = Create(classDefinition, propertyName, isMandatory, propertyType);
+      var relationEndPointDefinition = Create(typeDefinition, propertyName, isMandatory, propertyType);
       if (sortExpression != null)
         PrivateInvoke.InvokeNonPublicMethod(relationEndPointDefinition, "SetHasSortExpressionFlag");
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualObjectRelationEndPointDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualObjectRelationEndPointDefinitionTest.cs
index 64329b6063..96b12f7518 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualObjectRelationEndPointDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Mapping/VirtualObjectRelationEndPointDefinitionTest.cs
@@ -25,16 +25,16 @@ namespace Remotion.Data.DomainObjects.UnitTests.Mapping
   [TestFixture]
   public class VirtualObjectRelationEndPointDefinitionTest : MappingReflectionTestBase
   {
-    private ClassDefinition _orderClassDefinition;
+    private TypeDefinition _orderTypeDefinition;
     private VirtualObjectRelationEndPointDefinition _orderOrderTicketEndPoint;
 
     public override void SetUp ()
     {
       base.SetUp();
 
-      _orderClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order));
+      _orderTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order));
       _orderOrderTicketEndPoint = VirtualObjectRelationEndPointDefinitionFactory.Create(
-          _orderClassDefinition,
+          _orderTypeDefinition,
           "OrderTicket",
           false,
           typeof(OrderTicket));
@@ -82,15 +82,15 @@ public void SetRelationDefinition ()
     [Test]
     public void PropertyInfo ()
     {
-      ClassDefinition employeeClassDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Employee));
+      TypeDefinition employeeTypeDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Employee));
       VirtualObjectRelationEndPointDefinition relationEndPointDefinition =
-          (VirtualObjectRelationEndPointDefinition)employeeClassDefinition.GetRelationEndPointDefinition(typeof(Employee) + ".Computer");
+          (VirtualObjectRelationEndPointDefinition)employeeTypeDefinition.GetRelationEndPointDefinition(typeof(Employee) + ".Computer");
       Assert.That(relationEndPointDefinition.PropertyInfo, Is.EqualTo(PropertyInfoAdapter.Create(typeof(Employee).GetProperty("Computer"))));
     }
 
-    private static ClassDefinition CreateOrderDefinition_WithEmptyMembers_AndDerivedClasses ()
+    private static TypeDefinition CreateOrderDefinition_WithEmptyMembers_AndDerivedClasses ()
     {
-      return ClassDefinitionObjectMother.CreateClassDefinition_WithEmptyMembers_AndDerivedClasses("Order", classType: typeof(Order));
+      return TypeDefinitionObjectMother.CreateClassDefinition_WithEmptyMembers_AndDerivedClasses("Order", classType: typeof(Order));
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/MixedStorageProviderTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/MixedStorageProviderTest.cs
index 82ad2d2395..d75b7878a5 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/MixedStorageProviderTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/MixedStorageProviderTest.cs
@@ -32,7 +32,7 @@ public void StorageProvidersCanBeMixed ()
     {
       using (MixinConfiguration.BuildFromActive().ForClass(typeof(StorageProvider)).Clear().AddMixins(typeof(StorageProviderWithFixedGuidMixin)).EnterScope())
       {
-        ClassDefinition orderDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
+        TypeDefinition orderDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
         StorageProvider provider =
             new StorageProviderManager(NullPersistenceExtension.Instance, StorageSettings).GetMandatory(orderDefinition.StorageEntityDefinition.StorageProviderDefinition);
         Assert.That(Mixin.Get<StorageProviderWithFixedGuidMixin>(provider), Is.Not.Null);
@@ -44,7 +44,7 @@ public void MixinsCanOverrideStorageProviderMethods ()
     {
       using (MixinConfiguration.BuildFromActive().ForClass(typeof(StorageProvider)).Clear().AddMixins(typeof(StorageProviderWithFixedGuidMixin)).EnterScope())
       {
-        ClassDefinition orderDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
+        ClassDefinition orderDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Order));
         StorageProvider provider =
             new StorageProviderManager(NullPersistenceExtension.Instance, StorageSettings)
                 .GetMandatory(orderDefinition.StorageEntityDefinition.StorageProviderDefinition);
@@ -59,7 +59,7 @@ public void MixinsCanIntroduceStorageProviderInterfaces ()
     {
       using (MixinConfiguration.BuildFromActive().ForClass(typeof(StorageProvider)).Clear().AddMixins(typeof(StorageProviderWithFixedGuidMixin)).EnterScope())
       {
-        ClassDefinition orderDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
+        ClassDefinition orderDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Order));
         StorageProvider provider =
             new StorageProviderManager(NullPersistenceExtension.Instance, StorageSettings)
                 .GetMandatory(orderDefinition.StorageEntityDefinition.StorageProviderDefinition);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/Model/Validation/PropertyStorageClassIsSupportedByStorageProviderValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/Model/Validation/PropertyStorageClassIsSupportedByStorageProviderValidationRuleTest.cs
index c546f7fc03..83554871b8 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/Model/Validation/PropertyStorageClassIsSupportedByStorageProviderValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/Model/Validation/PropertyStorageClassIsSupportedByStorageProviderValidationRuleTest.cs
@@ -32,7 +32,7 @@ namespace Remotion.Data.DomainObjects.UnitTests.Persistence.NonPersistent.Model.
   public class PropertyStorageClassIsSupportedByStorageProviderValidationRuleTest : ValidationRuleTestBase
   {
     private PropertyStorageClassIsSupportedByStorageProviderValidationRule _validationRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
     private Mock<IStorageEntityDefinition> _persistentStorageEntityDefinition;
     private IStorageEntityDefinition _nonPersistentStorageEntityDefinition;
 
@@ -40,7 +40,7 @@ public class PropertyStorageClassIsSupportedByStorageProviderValidationRuleTest
     public void SetUp ()
     {
       _validationRule = new PropertyStorageClassIsSupportedByStorageProviderValidationRule();
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedValidationDomainObjectClass));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixinsAndDefaultProperties(typeof(DerivedValidationDomainObjectClass));
       _persistentStorageEntityDefinition = new Mock<IStorageEntityDefinition>();
       _nonPersistentStorageEntityDefinition =
           new NonPersistentStorageEntity(new NonPersistentProviderDefinition("NonPersistent", new NonPersistentStorageObjectFactory()));
@@ -50,7 +50,7 @@ public void SetUp ()
     public void PropertyWithStorageClassNone ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("PropertyWithStorageClassNone")),
           "PropertyWithStorageClassNone",
           false,
@@ -58,11 +58,11 @@ public void PropertyWithStorageClassNone ()
           20,
           StorageClass.None,
           null);
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetStorageEntity(_nonPersistentStorageEntityDefinition);
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetStorageEntity(_nonPersistentStorageEntityDefinition);
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -71,7 +71,7 @@ public void PropertyWithStorageClassNone ()
     public void PropertyWithStorageClassTransaction ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("PropertyWithStorageClassTransaction")),
           "PropertyWithStorageClassTransaction",
           false,
@@ -79,11 +79,11 @@ public void PropertyWithStorageClassTransaction ()
           20,
           StorageClass.Transaction,
           null);
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetStorageEntity(_nonPersistentStorageEntityDefinition);
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetStorageEntity(_nonPersistentStorageEntityDefinition);
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -92,7 +92,7 @@ public void PropertyWithStorageClassTransaction ()
     public void PropertyWithStorageClassPersistent ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("PropertyWithTypeObjectWithStorageClassPersistent")),
           "PropertyWithTypeObjectWithStorageClassPersistent",
           false,
@@ -100,11 +100,11 @@ public void PropertyWithStorageClassPersistent ()
           20,
           StorageClass.Persistent,
           null);
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetStorageEntity(_persistentStorageEntityDefinition.Object);
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetStorageEntity(_persistentStorageEntityDefinition.Object);
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -113,7 +113,7 @@ public void PropertyWithStorageClassPersistent ()
     public void PropertyWithStorageClassPersistent_StorageEntityDefinitionIsNotSet ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("PropertyWithTypeObjectWithStorageClassPersistent")),
           "PropertyWithTypeObjectWithStorageClassPersistent",
           false,
@@ -121,10 +121,10 @@ public void PropertyWithStorageClassPersistent_StorageEntityDefinitionIsNotSet (
           null,
           StorageClass.Persistent,
           null);
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -133,7 +133,7 @@ public void PropertyWithStorageClassPersistent_StorageEntityDefinitionIsNotSet (
     public void PropertyWithStorageClassPersistent_UnsupportedStorageEntityDefinition ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("PropertyWithTypeObjectWithStorageClassPersistent")),
           "PropertyWithTypeObjectWithStorageClassPersistent",
           false,
@@ -141,11 +141,11 @@ public void PropertyWithStorageClassPersistent_UnsupportedStorageEntityDefinitio
           null,
           StorageClass.Persistent,
           null);
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
-      _classDefinition.SetStorageEntity(_nonPersistentStorageEntityDefinition);
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { propertyDefinition }, true));
+      _typeDefinition.SetStorageEntity(_nonPersistentStorageEntityDefinition);
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       var expectedMessage =
           "StorageClass.Persistent is not supported for properties of classes that belong to the 'NonPersistentProviderDefinition'.\r\n\r\n"
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/Model/Validation/RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/Model/Validation/RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRuleTest.cs
similarity index 76%
rename from Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/Model/Validation/RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRuleTest.cs
rename to Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/Model/Validation/RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRuleTest.cs
index 643bcf13c5..872b65d7ef 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/Model/Validation/RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/Model/Validation/RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRuleTest.cs
@@ -29,11 +29,11 @@
 namespace Remotion.Data.DomainObjects.UnitTests.Persistence.NonPersistent.Model.Validation
 {
   [TestFixture]
-  public class RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRuleTest: ValidationRuleTestBase
+  public class RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRuleTest: ValidationRuleTestBase
   {
-    private RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRule _validationRule;
-    private ClassDefinition _persistentClassDefinition;
-    private ClassDefinition _nonPersistentClassDefinition;
+    private RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRule _validationRule;
+    private TypeDefinition _persistentTypeDefinition;
+    private TypeDefinition _nonPersistentTypeDefinition;
     private PropertyDefinition _persistentPropertyDefinition;
     private PropertyDefinition _transactionPropertyDefinitionOnPersistentClassDefinition;
     private PropertyDefinition _transactionPropertyDefinitionOnNonPersistentClassDefinition;
@@ -44,25 +44,25 @@ public class RelationPropertyStorageClassMatchesReferencedClassDefinitionStorage
     [SetUp]
     public void SetUp ()
     {
-      _validationRule = new RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRule();
+      _validationRule = new RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRule();
 
-      _persistentClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(
+      _persistentTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties(
           "Order",
           typeof(Order),
           storageGroupType: typeof(TestDomainAttribute));
       _persistentStorageEntityDefinition = new Mock<IStorageEntityDefinition>();
-      _persistentClassDefinition.SetStorageEntity(_persistentStorageEntityDefinition.Object);
+      _persistentTypeDefinition.SetStorageEntity(_persistentStorageEntityDefinition.Object);
 
-      _nonPersistentClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition(
+      _nonPersistentTypeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties(
           "OrderViewModel",
           typeof(OrderViewModel),
           storageGroupType: typeof(NonPersistentTestDomainAttribute));
       _nonPersistentStorageEntityDefinition =
           new NonPersistentStorageEntity(new NonPersistentProviderDefinition("NonPersistent", new NonPersistentStorageObjectFactory()));
-      _nonPersistentClassDefinition.SetStorageEntity(_nonPersistentStorageEntityDefinition);
+      _nonPersistentTypeDefinition.SetStorageEntity(_nonPersistentStorageEntityDefinition);
 
       _persistentPropertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(
-          _persistentClassDefinition,
+          _persistentTypeDefinition,
           "PersistentProperty1",
           isObjectID: true,
           typeof(OrderViewModel),
@@ -71,7 +71,7 @@ public void SetUp ()
           StorageClass.Persistent);
 
       _transactionPropertyDefinitionOnPersistentClassDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(
-          _persistentClassDefinition,
+          _persistentTypeDefinition,
           "TransactionPropertyPersistentClassDefinition",
           isObjectID: true,
           typeof(OrderViewModel),
@@ -80,7 +80,7 @@ public void SetUp ()
           StorageClass.Transaction);
 
       _transactionPropertyDefinitionOnNonPersistentClassDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(
-          _nonPersistentClassDefinition,
+          _nonPersistentTypeDefinition,
           "TransactionPropertyOnNonPersistentClassDefinition",
           isObjectID: true,
           typeof(OrderViewModel),
@@ -93,15 +93,15 @@ public void SetUp ()
     public void RelationEndPointHasStorageClassTransaction_AndAnonymousEndPointHasPersistentClassDefinition ()
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_transactionPropertyDefinitionOnPersistentClassDefinition, false);
-      var rightEndPointDefinition = new AnonymousRelationEndPointDefinition(_persistentClassDefinition);
+      var rightEndPointDefinition = new AnonymousRelationEndPointDefinition(_persistentTypeDefinition);
       var relationDefinition = new RelationDefinition("Test", leftEndPointDefinition, rightEndPointDefinition);
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { leftEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { leftEndPointDefinition }, true));
+      _persistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -111,7 +111,7 @@ public void RelationEndPointHasStorageClassTransaction_AndVirtualObjectRelationE
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_transactionPropertyDefinitionOnPersistentClassDefinition, false);
       var rightEndPointDefinition = VirtualObjectRelationEndPointDefinitionFactory.Create(
-          _persistentClassDefinition,
+          _persistentTypeDefinition,
           "Right",
           false,
           typeof(DomainObject));
@@ -119,11 +119,11 @@ public void RelationEndPointHasStorageClassTransaction_AndVirtualObjectRelationE
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(
           new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[] { leftEndPointDefinition, rightEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -133,7 +133,7 @@ public void RelationEndPointHasStorageClassTransaction_AndDomainObjectCollection
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_transactionPropertyDefinitionOnPersistentClassDefinition, false);
       var rightEndPointDefinition = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _persistentClassDefinition,
+          _persistentTypeDefinition,
           "Right",
           false,
           typeof(ObjectList<DomainObject>));
@@ -141,11 +141,11 @@ public void RelationEndPointHasStorageClassTransaction_AndDomainObjectCollection
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(
           new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[] { leftEndPointDefinition, rightEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -155,7 +155,7 @@ public void RelationEndPointHasStorageClassTransaction_AndQueryCollectionRelatio
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_transactionPropertyDefinitionOnPersistentClassDefinition, false);
       var rightEndPointDefinition = VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          _persistentClassDefinition,
+          _persistentTypeDefinition,
           "Right",
           false,
           typeof(IObjectList<DomainObject>));
@@ -163,11 +163,11 @@ public void RelationEndPointHasStorageClassTransaction_AndQueryCollectionRelatio
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(
           new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[] { leftEndPointDefinition, rightEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -176,18 +176,18 @@ public void RelationEndPointHasStorageClassTransaction_AndQueryCollectionRelatio
     public void RelationEndPointHasStorageClassTransaction_AndAnonymousEndPointHasNonPersistentClassDefinition ()
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_transactionPropertyDefinitionOnPersistentClassDefinition, false);
-      var rightEndPointDefinition = new AnonymousRelationEndPointDefinition(_nonPersistentClassDefinition);
+      var rightEndPointDefinition = new AnonymousRelationEndPointDefinition(_nonPersistentTypeDefinition);
       var relationDefinition = new RelationDefinition("Test", leftEndPointDefinition, rightEndPointDefinition);
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { leftEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { leftEndPointDefinition }, true));
+      _persistentTypeDefinition.SetReadOnly();
 
-      _nonPersistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[0], true));
-      _nonPersistentClassDefinition.SetReadOnly();
+      _nonPersistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[0], true));
+      _nonPersistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -197,7 +197,7 @@ public void RelationEndPointHasStorageClassTransaction_AndVirtualObjectRelationE
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_transactionPropertyDefinitionOnPersistentClassDefinition, false);
       var rightEndPointDefinition = VirtualObjectRelationEndPointDefinitionFactory.Create(
-          _nonPersistentClassDefinition,
+          _nonPersistentTypeDefinition,
           "Right",
           false,
           typeof(DomainObject));
@@ -205,13 +205,13 @@ public void RelationEndPointHasStorageClassTransaction_AndVirtualObjectRelationE
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
+      _persistentTypeDefinition.SetReadOnly();
 
-      _nonPersistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
-      _nonPersistentClassDefinition.SetReadOnly();
+      _nonPersistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
+      _nonPersistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -221,7 +221,7 @@ public void RelationEndPointHasStorageClassTransaction_AndDomainObjectCollection
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_transactionPropertyDefinitionOnPersistentClassDefinition, false);
       var rightEndPointDefinition = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _nonPersistentClassDefinition,
+          _nonPersistentTypeDefinition,
           "Right",
           false,
           typeof(ObjectList<DomainObject>));
@@ -229,13 +229,13 @@ public void RelationEndPointHasStorageClassTransaction_AndDomainObjectCollection
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
+      _persistentTypeDefinition.SetReadOnly();
 
-      _nonPersistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
-      _nonPersistentClassDefinition.SetReadOnly();
+      _nonPersistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
+      _nonPersistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -245,7 +245,7 @@ public void RelationEndPointHasStorageClassTransaction_AndVirtualCollectionRelat
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_transactionPropertyDefinitionOnPersistentClassDefinition, false);
       var rightEndPointDefinition = VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          _nonPersistentClassDefinition,
+          _nonPersistentTypeDefinition,
           "Right",
           false,
           typeof(IObjectList<DomainObject>));
@@ -253,13 +253,13 @@ public void RelationEndPointHasStorageClassTransaction_AndVirtualCollectionRelat
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
+      _persistentTypeDefinition.SetReadOnly();
 
-      _nonPersistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
-      _nonPersistentClassDefinition.SetReadOnly();
+      _nonPersistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
+      _nonPersistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -268,15 +268,15 @@ public void RelationEndPointHasStorageClassTransaction_AndVirtualCollectionRelat
     public void RelationEndPointHasStorageClassPersistent_AndAnonymousEndPointHasPersistentClassDefinition ()
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_persistentPropertyDefinition, false);
-      var rightEndPointDefinition = new AnonymousRelationEndPointDefinition(_persistentClassDefinition);
+      var rightEndPointDefinition = new AnonymousRelationEndPointDefinition(_persistentTypeDefinition);
       var relationDefinition = new RelationDefinition("Test", leftEndPointDefinition, rightEndPointDefinition);
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { leftEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { leftEndPointDefinition }, true));
+      _persistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -286,7 +286,7 @@ public void RelationEndPointHasStorageClassPersistent_AndVirtualObjectRelationEn
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_persistentPropertyDefinition, false);
       var rightEndPointDefinition = VirtualObjectRelationEndPointDefinitionFactory.Create(
-          _persistentClassDefinition,
+          _persistentTypeDefinition,
           "Right",
           false,
           typeof(DomainObject));
@@ -294,11 +294,11 @@ public void RelationEndPointHasStorageClassPersistent_AndVirtualObjectRelationEn
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(
           new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[] { leftEndPointDefinition, rightEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -308,7 +308,7 @@ public void RelationEndPointHasStorageClassPersistent_AndDomainObjectCollectionR
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_persistentPropertyDefinition, false);
       var rightEndPointDefinition = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _persistentClassDefinition,
+          _persistentTypeDefinition,
           "Right",
           false,
           typeof(ObjectList<DomainObject>));
@@ -316,11 +316,11 @@ public void RelationEndPointHasStorageClassPersistent_AndDomainObjectCollectionR
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(
           new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[] { leftEndPointDefinition, rightEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -330,7 +330,7 @@ public void RelationEndPointHasStorageClassPersistent_AndVirtualCollectionRelati
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_persistentPropertyDefinition, false);
       var rightEndPointDefinition = VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          _persistentClassDefinition,
+          _persistentTypeDefinition,
           "Right",
           false,
           typeof(IObjectList<DomainObject>));
@@ -338,11 +338,11 @@ public void RelationEndPointHasStorageClassPersistent_AndVirtualCollectionRelati
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(
           new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[] { leftEndPointDefinition, rightEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -352,16 +352,16 @@ public void RelationEndPointHasStorageClassPersistent_RelationDefinitionIsNotSet
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_persistentPropertyDefinition, false);
       var rightEndPointDefinition = VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          _persistentClassDefinition,
+          _persistentTypeDefinition,
           "Right",
           false,
           typeof(IObjectList<DomainObject>));
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(
           new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[] { leftEndPointDefinition, rightEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -370,18 +370,18 @@ public void RelationEndPointHasStorageClassPersistent_RelationDefinitionIsNotSet
     public void RelationEndPointHasStorageClassPersistent_AndAnonymousEndPointHasNonPersistentClassDefinition ()
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_persistentPropertyDefinition, false);
-      var rightEndPointDefinition = new AnonymousRelationEndPointDefinition(_nonPersistentClassDefinition);
+      var rightEndPointDefinition = new AnonymousRelationEndPointDefinition(_nonPersistentTypeDefinition);
       var relationDefinition = new RelationDefinition("Test", leftEndPointDefinition, rightEndPointDefinition);
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { leftEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { leftEndPointDefinition }, true));
+      _persistentTypeDefinition.SetReadOnly();
 
-      _nonPersistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[0], true));
-      _nonPersistentClassDefinition.SetReadOnly();
+      _nonPersistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new IRelationEndPointDefinition[0], true));
+      _nonPersistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       var expectedMessage =
           "The relation property is defined as persistent but the referenced type "
@@ -397,7 +397,7 @@ public void RelationEndPointHasStorageClassPersistent_AndVirtualObjectRelationEn
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_persistentPropertyDefinition, false);
       var rightEndPointDefinition = VirtualObjectRelationEndPointDefinitionFactory.Create(
-          _nonPersistentClassDefinition,
+          _nonPersistentTypeDefinition,
           "Right",
           false,
           typeof(DomainObject));
@@ -405,13 +405,13 @@ public void RelationEndPointHasStorageClassPersistent_AndVirtualObjectRelationEn
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
+      _persistentTypeDefinition.SetReadOnly();
 
-      _nonPersistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
-      _nonPersistentClassDefinition.SetReadOnly();
+      _nonPersistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
+      _nonPersistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       var expectedMessage =
           "The relation property is defined as persistent but the referenced type "
@@ -427,7 +427,7 @@ public void RelationEndPointHasStorageClassPersistent_AndDomainObjectCollectionR
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_persistentPropertyDefinition, false);
       var rightEndPointDefinition = DomainObjectCollectionRelationEndPointDefinitionFactory.Create(
-          _nonPersistentClassDefinition,
+          _nonPersistentTypeDefinition,
           "Right",
           false,
           typeof(ObjectList<DomainObject>));
@@ -435,13 +435,13 @@ public void RelationEndPointHasStorageClassPersistent_AndDomainObjectCollectionR
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
+      _persistentTypeDefinition.SetReadOnly();
 
-      _nonPersistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
-      _nonPersistentClassDefinition.SetReadOnly();
+      _nonPersistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
+      _nonPersistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       var expectedMessage =
           "The relation property is defined as persistent but the referenced type "
@@ -457,7 +457,7 @@ public void RelationEndPointHasStorageClassPersistent_AndVirtualCollectionRelati
     {
       var leftEndPointDefinition = new RelationEndPointDefinition(_persistentPropertyDefinition, false);
       var rightEndPointDefinition = VirtualCollectionRelationEndPointDefinitionFactory.Create(
-          _nonPersistentClassDefinition,
+          _nonPersistentTypeDefinition,
           "Right",
           false,
           typeof(IObjectList<DomainObject>));
@@ -465,13 +465,13 @@ public void RelationEndPointHasStorageClassPersistent_AndVirtualCollectionRelati
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { leftEndPointDefinition }, true));
+      _persistentTypeDefinition.SetReadOnly();
 
-      _nonPersistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
-      _nonPersistentClassDefinition.SetReadOnly();
+      _nonPersistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new [] { rightEndPointDefinition }, true));
+      _nonPersistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       var expectedMessage =
           "The relation property is defined as persistent but the referenced type "
@@ -491,13 +491,13 @@ public void RelationEndPointHasStorageClassPersistent_AndSecondEndPointIsAlsoRea
       leftEndPointDefinition.SetRelationDefinition(relationDefinition);
       rightEndPointDefinition.SetRelationDefinition(relationDefinition);
 
-      _persistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { leftEndPointDefinition }, true));
-      _persistentClassDefinition.SetReadOnly();
+      _persistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { leftEndPointDefinition }, true));
+      _persistentTypeDefinition.SetReadOnly();
 
-      _nonPersistentClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { rightEndPointDefinition }, true));
-      _nonPersistentClassDefinition.SetReadOnly();
+      _nonPersistentTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection(new[] { rightEndPointDefinition }, true));
+      _nonPersistentTypeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_persistentClassDefinition);
+      var validationResult = _validationRule.Validate(_persistentTypeDefinition);
 
       var expectedMessage =
           "The relation property is defined as persistent but the referenced type "
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/NonPersistentModelLoaderTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/NonPersistentModelLoaderTest.cs
index ed04ac2baa..9fc089320c 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/NonPersistentModelLoaderTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/NonPersistentModelLoaderTest.cs
@@ -50,7 +50,7 @@ public void SetUp ()
     [Test]
     public void CreatePersistenceMappingValidator ()
     {
-      var baseClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Base", classType: typeof(BaseClass), baseClass: null);
+      var baseClass = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(BaseClass), baseClass: null);
       baseClass.SetDerivedClasses(new ClassDefinition[0]);
       baseClass.SetPropertyDefinitions(new PropertyDefinitionCollection(new PropertyDefinition[0], true));
 
@@ -58,14 +58,14 @@ public void CreatePersistenceMappingValidator ()
 
       Assert.That(validator.ValidationRules.Count, Is.EqualTo(2));
       Assert.That(validator.ValidationRules[0], Is.TypeOf(typeof(PropertyStorageClassIsSupportedByStorageProviderValidationRule)));
-      Assert.That(validator.ValidationRules[1], Is.TypeOf(typeof(RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRule)));
+      Assert.That(validator.ValidationRules[1], Is.TypeOf(typeof(RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRule)));
     }
 
     [Test]
     public void ApplyPersistenceModelToHierarchy_CreatesEntities_AndProperties_ForClassAndDerivedClasses ()
     {
-      var baseClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Base", classType: typeof(BaseClass), baseClass: null);
-      var derivedClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Derived", classType: typeof(DerivedClass), baseClass: baseClass);
+      var baseClass = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(BaseClass), baseClass: null);
+      var derivedClass = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedClass), baseClass: baseClass);
       baseClass.SetDerivedClasses(new[] { derivedClass });
       derivedClass.SetDerivedClasses(new ClassDefinition[0]);
 
@@ -90,7 +90,7 @@ public void ApplyPersistenceModelToHierarchy_LeavesExistingEntities_AndPropertie
       var fakeEntityDefinition = new NonPersistentStorageEntity(fakeProviderDefinition);
       var fakeStoragePropertyDefinition = (NonPersistentStorageProperty)Activator.CreateInstance(typeof(NonPersistentStorageProperty), true);
 
-      var baseClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Base", classType: typeof(BaseClass), baseClass: null);
+      var baseClass = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(BaseClass), baseClass: null);
       baseClass.SetDerivedClasses(new ClassDefinition[0]);
       var persistentProperty = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(baseClass, "PersistentProperty", StorageClass.Persistent);
       baseClass.SetPropertyDefinitions(new PropertyDefinitionCollection(new[] { persistentProperty }, true));
@@ -109,7 +109,7 @@ public void ApplyPersistenceModelToHierarchy_Throws_WhenExistingEntityDefinition
     {
       var invalidStorageEntityDefinition = new Mock<IStorageEntityDefinition>();
 
-      var baseClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Base", classType: typeof(BaseClass), baseClass: null);
+      var baseClass = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(BaseClass), baseClass: null);
       baseClass.SetDerivedClasses(new ClassDefinition[0]);
 
       baseClass.SetStorageEntity(invalidStorageEntityDefinition.Object);
@@ -118,13 +118,14 @@ public void ApplyPersistenceModelToHierarchy_Throws_WhenExistingEntityDefinition
       Assert.That(
           () => _persistenceModelLoader.ApplyPersistenceModelToHierarchy(baseClass),
           Throws.InvalidOperationException.With.Message.EqualTo(
-              "The storage entity definition of class 'Base' is not of type 'NonPersistentStorageEntity'."));
+              "The storage entity definition of type "
+              + "'Remotion.Data.DomainObjects.UnitTests.Persistence.NonPersistent.Model.NonPersistentPersistenceModelLoaderTestDomain.BaseClass' is not of type 'NonPersistentStorageEntity'."));
     }
 
     [Test]
     public void ApplyPersistenceModelToHierarchy_Throws_WhenExistingPropertyDefinitionDoesNotImplementIColumnDefinition ()
     {
-      var baseClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "Base", classType: typeof(BaseClass), baseClass: null);
+      var baseClass = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(BaseClass), baseClass: null);
       baseClass.SetDerivedClasses(new ClassDefinition[0]);
 
       var persistentProperty = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(baseClass, "PersistentProperty", StorageClass.Persistent);
@@ -135,7 +136,8 @@ public void ApplyPersistenceModelToHierarchy_Throws_WhenExistingPropertyDefiniti
       Assert.That(
           () => _persistenceModelLoader.ApplyPersistenceModelToHierarchy(baseClass),
           Throws.InvalidOperationException.With.Message.EqualTo(
-              "The property definition 'PersistentProperty' of class 'Base' has a storage property type of "
+              "The property definition 'PersistentProperty' of type "
+              + "'Remotion.Data.DomainObjects.UnitTests.Persistence.NonPersistent.Model.NonPersistentPersistenceModelLoaderTestDomain.BaseClass' has a storage property type of "
               + "'Remotion.Data.DomainObjects.UnitTests.Mapping.FakeStoragePropertyDefinition' when only 'NonPersistentStorageProperty' is supported."));
     }
   }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/NonPersistentProviderTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/NonPersistentProviderTest.cs
index a252eae45d..0f91014354 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/NonPersistentProviderTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/NonPersistent/NonPersistentProviderTest.cs
@@ -57,7 +57,7 @@ public void CreateNewObjectID_ClassDefinitionWithDifferentStorageProviderDefinit
       Assert.That(
           () => providerWithDifferentID.CreateNewObjectID(DomainObjectIDs.OrderViewModel1.ClassDefinition),
           Throws.Exception.TypeOf<ArgumentException>().With.ArgumentExceptionMessageEqualTo(
-              "The StorageProviderID 'NonPersistentTestDomain' of the provided ClassDefinition does not match with this StorageProvider's ID 'Test'.", "classDefinition"));
+              "The StorageProviderID 'NonPersistentTestDomain' of the provided TypeDefinition does not match with this StorageProvider's ID 'Test'.", "classDefinition"));
     }
 
     [Test]
@@ -172,7 +172,7 @@ public void LoadDataContainersByRelatedID_ClassDefinitionWithDifferentStoragePro
       Assert.That(
           () => providerWithDifferentID.LoadDataContainersByRelatedID(relationEndPointDefinition, null, objectID),
           Throws.Exception.TypeOf<ArgumentException>().With.ArgumentExceptionMessageEqualTo(
-              "The StorageProviderID 'NonPersistentTestDomain' of the provided ClassDefinition does not match with this StorageProvider's ID 'Test'.", "classDefinition"));
+              "The StorageProviderID 'NonPersistentTestDomain' of the provided TypeDefinition does not match with this StorageProvider's ID 'Test'.", "typeDefinition"));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/PersistenceManagerTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/PersistenceManagerTest.cs
index 4d605057db..0f118fef8d 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/PersistenceManagerTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/PersistenceManagerTest.cs
@@ -645,7 +645,7 @@ public void Save_DeletedDataContainersAreIgnoredForUpdateTimestamps ()
     [Test]
     public void CreateNewObjectID ()
     {
-      ClassDefinition orderClass = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
+      ClassDefinition orderClass = MappingConfiguration.Current.GetClassDefinition(typeof(Order));
       ObjectID id1 = _persistenceManager.CreateNewObjectID(orderClass);
       Assert.That(id1, Is.Not.Null);
       ObjectID id2 = _persistenceManager.CreateNewObjectID(orderClass);
@@ -656,7 +656,7 @@ public void CreateNewObjectID ()
     [Test]
     public void CreateNewDataContainer ()
     {
-      ClassDefinition orderClass = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
+      ClassDefinition orderClass = MappingConfiguration.Current.GetClassDefinition(typeof(Order));
       DataContainer container = CreateDataContainer(orderClass);
 
       Assert.That(container, Is.Not.Null);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/ColumnSerializerTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/ColumnSerializerTest.cs
index 6a11289601..956350b33d 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/ColumnSerializerTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/ColumnSerializerTest.cs
@@ -31,10 +31,10 @@ public class ColumnSerializerTest : SchemaGenerationTestBase
     public void Serialize_CreatesColumnElement ()
     {
       var propertyDefinition = GetPropertyDefinition((ClassWithAllDataTypes _) => _.Int32Property);
-      var classDefinition = propertyDefinition.ClassDefinition;
+      var typeDefinition = propertyDefinition.TypeDefinition;
 
       var columnSerializer = new ColumnSerializer();
-      var actual = columnSerializer.Serialize(propertyDefinition, GetRdbmsPersistenceModelProvider(classDefinition)).ToArray();
+      var actual = columnSerializer.Serialize(propertyDefinition, GetRdbmsPersistenceModelProvider(typeDefinition)).ToArray();
 
       Assert.That(actual.Length, Is.EqualTo(1));
       Assert.That(actual[0].Name.LocalName, Is.EqualTo("column"));
@@ -44,10 +44,10 @@ public void Serialize_CreatesColumnElement ()
     public void Serialize_AddsNameAttribute ()
     {
       var propertyDefinition = GetPropertyDefinition((ClassWithAllDataTypes _) => _.Int32Property);
-      var classDefinition = propertyDefinition.ClassDefinition;
+      var typeDefinition = propertyDefinition.TypeDefinition;
 
       var columnSerializer = new ColumnSerializer();
-      var actual = columnSerializer.Serialize(propertyDefinition, GetRdbmsPersistenceModelProvider(classDefinition)).Single();
+      var actual = columnSerializer.Serialize(propertyDefinition, GetRdbmsPersistenceModelProvider(typeDefinition)).Single();
 
       Assert.That(actual.Attributes().Select(a => a.Name.LocalName), Contains.Item("name"));
       Assert.That(actual.Attribute("name").Value, Is.EqualTo("Int32"));
@@ -57,10 +57,10 @@ public void Serialize_AddsNameAttribute ()
     public void Serialize_AddsTypeAttribute ()
     {
       var propertyDefinition = GetPropertyDefinition((ClassWithAllDataTypes _) => _.Int32Property);
-      var classDefinition = propertyDefinition.ClassDefinition;
+      var typeDefinition = propertyDefinition.TypeDefinition;
 
       var columnSerializer = new ColumnSerializer();
-      var actual = columnSerializer.Serialize(propertyDefinition, GetRdbmsPersistenceModelProvider(classDefinition)).Single();
+      var actual = columnSerializer.Serialize(propertyDefinition, GetRdbmsPersistenceModelProvider(typeDefinition)).Single();
 
       Assert.That(actual.Attributes().Select(a => a.Name.LocalName), Contains.Item("dbType"));
       Assert.That(actual.Attribute("dbType").Value, Is.EqualTo("Int32"));
@@ -70,10 +70,10 @@ public void Serialize_AddsTypeAttribute ()
     public void Serialize_RelationProperty ()
     {
       var propertyDefinition = GetPropertyDefinition((Ceo _) => _.Company);
-      var classDefinition = propertyDefinition.ClassDefinition;
+      var typeDefinition = propertyDefinition.TypeDefinition;
 
       var columnSerializer = new ColumnSerializer();
-      var actual = columnSerializer.Serialize(propertyDefinition, GetRdbmsPersistenceModelProvider(classDefinition)).ToArray();
+      var actual = columnSerializer.Serialize(propertyDefinition, GetRdbmsPersistenceModelProvider(typeDefinition)).ToArray();
 
       Assert.That(actual.Length, Is.EqualTo(2));
       Assert.That(actual[0].Attribute("name").Value, Is.EqualTo("CompanyID"));
@@ -82,9 +82,9 @@ public void Serialize_RelationProperty ()
       Assert.That(actual[1].Attribute("dbType").Value, Is.EqualTo("AnsiString"));
     }
 
-    private IRdbmsPersistenceModelProvider GetRdbmsPersistenceModelProvider (ClassDefinition classDefinition)
+    private IRdbmsPersistenceModelProvider GetRdbmsPersistenceModelProvider (TypeDefinition typeDefinition)
     {
-      var storageProviderDefinition = (RdbmsProviderDefinition)classDefinition.StorageEntityDefinition.StorageProviderDefinition;
+      var storageProviderDefinition = (RdbmsProviderDefinition)typeDefinition.StorageEntityDefinition.StorageProviderDefinition;
       var persistenceModelProvider = storageProviderDefinition.Factory.CreateRdbmsPersistenceModelProvider(storageProviderDefinition);
       return persistenceModelProvider;
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/MappingSerializerTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/MappingSerializerTest.cs
index e07773609f..bb71dfc4d4 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/MappingSerializerTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/MappingSerializerTest.cs
@@ -90,7 +90,7 @@ public void Serialize_AddsStorageProviderElements ()
       enumSerializerStub.Setup(_ => _.Serialize()).Returns(new XElement[0]);
 
       var expected = new XElement("storageProvider");
-      storageProviderSerializerStub.Setup(_ => _.Serialize(It.IsAny<IEnumerable<ClassDefinition>>(), It.IsAny<RdbmsProviderDefinition>())).Returns(expected);
+      storageProviderSerializerStub.Setup(_ => _.Serialize(It.IsAny<IEnumerable<TypeDefinition>>(), It.IsAny<RdbmsProviderDefinition>())).Returns(expected);
 
       var actual = _mappingSerializer.Serialize(MappingConfiguration.Current.GetTypeDefinitions());
 
@@ -108,7 +108,7 @@ public void Serialize_AddsEnumTypes ()
       var storageProviderElement = new XElement("storageProvider");
       var enumTypeElement = new XElement("enumType");
 
-      storageProviderSerializerStub.Setup(_ => _.Serialize(It.IsAny<IEnumerable<ClassDefinition>>(), It.IsAny<RdbmsProviderDefinition>())).Returns(storageProviderElement);
+      storageProviderSerializerStub.Setup(_ => _.Serialize(It.IsAny<IEnumerable<TypeDefinition>>(), It.IsAny<RdbmsProviderDefinition>())).Returns(storageProviderElement);
       enumSerializerStub.Setup(_ => _.Serialize()).Returns(new[] { enumTypeElement });
 
       var actual = _mappingSerializer.Serialize(MappingConfiguration.Current.GetTypeDefinitions());
@@ -118,10 +118,10 @@ public void Serialize_AddsEnumTypes ()
     }
 
     [Test]
-    public void Serialize_GroupsClassDefinitionsByStorageProvider ()
+    public void Serialize_GroupsTypeDefinitionsByStorageProvider ()
     {
-      var classDefinitions = MappingConfiguration.Current.GetTypeDefinitions();
-      var storageProviders = classDefinitions
+      var typeDefinitions = MappingConfiguration.Current.GetTypeDefinitions();
+      var storageProviders = typeDefinitions
           .Select(c => c.StorageEntityDefinition.StorageProviderDefinition).Distinct().OfType<RdbmsProviderDefinition>().ToArray();
 
       var enumSerializerStub = new Mock<IEnumSerializer>();
@@ -136,12 +136,12 @@ public void Serialize_GroupsClassDefinitionsByStorageProvider ()
         _storageProviderSerializerFactoryStub.Setup(_ => _(rdbmsProviderDefinition, enumSerializerStub.Object)).Returns(storageProviderSerializerMock.Object);
 
         storageProviderSerializerMock
-            .Setup(_ => _.Serialize(It.IsAny<IEnumerable<ClassDefinition>>(), rdbmsProviderDefinition))
+            .Setup(_ => _.Serialize(It.IsAny<IEnumerable<TypeDefinition>>(), rdbmsProviderDefinition))
             .Returns(new XElement("storageProvider"))
             .Verifiable();
       }
 
-      _mappingSerializer.Serialize(classDefinitions);
+      _mappingSerializer.Serialize(typeDefinitions);
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/StorageProviderSerializerTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/StorageProviderSerializerTest.cs
index b1388eab69..8cb4e592d5 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/StorageProviderSerializerTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/StorageProviderSerializerTest.cs
@@ -32,13 +32,13 @@ public class StorageProviderSerializerTest : SchemaGenerationTestBase
     [Test]
     public void Serialize_AddsNameAttribute ()
     {
-      var classDefinitions = MappingConfiguration.Current.GetTypeDefinitions();
-      var groupedByStorageProvider = classDefinitions
+      var typeDefinitions = MappingConfiguration.Current.GetTypeDefinitions();
+      var groupedByStorageProvider = typeDefinitions
           .Where(c => c.StorageEntityDefinition.StorageProviderDefinition is RdbmsProviderDefinition)
           .GroupBy(c => (RdbmsProviderDefinition)c.StorageEntityDefinition.StorageProviderDefinition)
           .First();
 
-      var storageProviderSerializer = new StorageProviderSerializer(new Mock<IClassSerializer>().Object);
+      var storageProviderSerializer = new StorageProviderSerializer(new Mock<ITypeSerializer>().Object);
       var actual = storageProviderSerializer.Serialize(groupedByStorageProvider, groupedByStorageProvider.Key);
 
       Assert.That(actual.Attributes().Select(a => a.Name.LocalName), Contains.Item("name"));
@@ -48,19 +48,19 @@ public void Serialize_AddsNameAttribute ()
     [Test]
     public void Serialize_AddsClassElements ()
     {
-      var classDefinitions = MappingConfiguration.Current.GetTypeDefinitions();
-      var groupedByStorageProvider = classDefinitions
+      var typeDefinitions = MappingConfiguration.Current.GetTypeDefinitions();
+      var groupedByStorageProvider = typeDefinitions
           .Where(c => c.StorageEntityDefinition.StorageProviderDefinition is RdbmsProviderDefinition)
           .GroupBy(c => (RdbmsProviderDefinition)c.StorageEntityDefinition.StorageProviderDefinition)
           .First();
 
-      var classSerializerStub = new Mock<IClassSerializer>();
+      var typeSerializerStub = new Mock<ITypeSerializer>();
       var expectedElement = new XElement("class");
-      classSerializerStub
+      typeSerializerStub
           .Setup(_ => _.Serialize(It.IsNotNull<ClassDefinition>()))
           .Returns(expectedElement);
 
-      var storageProviderSerializer = new StorageProviderSerializer(classSerializerStub.Object);
+      var storageProviderSerializer = new StorageProviderSerializer(typeSerializerStub.Object);
       var actual = storageProviderSerializer.Serialize(groupedByStorageProvider, groupedByStorageProvider.Key);
 
       Assert.That(actual.Elements(), Is.Not.Empty);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/TableSerializerTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/TableSerializerTest.cs
index db9ec3d587..86aa7fd4e9 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/TableSerializerTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/TableSerializerTest.cs
@@ -54,7 +54,7 @@ public void Serialize_CreatesPersistenceModelProvider ()
           .Returns((XElement)null)
           .Verifiable();
 
-      tableSerializer.Serialize(MappingConfiguration.Current.GetTypeDefinition(typeof(ClassWithAllDataTypes))).ToArray();
+      tableSerializer.Serialize(MappingConfiguration.Current.GetClassDefinition(typeof(ClassWithAllDataTypes))).ToArray();
       propertySerializerMock.Verify(
           _ => _.Serialize(It.IsNotNull<PropertyDefinition>(), It.IsNotNull<IRdbmsPersistenceModelProvider>()),
           Times.AtLeastOnce());
@@ -63,7 +63,7 @@ public void Serialize_CreatesPersistenceModelProvider ()
     [Test]
     public void Serialize_AddsPropertyElements ()
     {
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Ceo));
+      var typeDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Ceo));
       var propertySerializerStub = new Mock<IPropertySerializer>();
       var expected1 = new XElement("property1");
       var expected2 = new XElement("property2");
@@ -71,18 +71,18 @@ public void Serialize_AddsPropertyElements ()
       propertySerializerStub
           .Setup(
               _ => _.Serialize(
-                  classDefinition.GetPropertyDefinition("Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.SchemaGenerationTestDomain.Ceo.Name"),
+                  typeDefinition.GetPropertyDefinition("Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.SchemaGenerationTestDomain.Ceo.Name"),
                   It.IsAny<IRdbmsPersistenceModelProvider>()))
           .Returns(expected1);
       propertySerializerStub
           .Setup(
               _ => _.Serialize(
-                  classDefinition.GetPropertyDefinition("Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.SchemaGenerationTestDomain.Ceo.Company"),
+                  typeDefinition.GetPropertyDefinition("Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.SchemaGenerationTestDomain.Ceo.Company"),
                   It.IsAny<IRdbmsPersistenceModelProvider>()))
           .Returns(expected2);
       var tableSerializer = new TableSerializer(propertySerializerStub.Object);
 
-      var actual = tableSerializer.Serialize(classDefinition).Single();
+      var actual = tableSerializer.Serialize(typeDefinition).Single();
 
       Assert.That(actual.Elements(), Is.EqualTo(new[] { expected1, expected2 }));
     }
@@ -90,7 +90,7 @@ public void Serialize_AddsPropertyElements ()
     [Test]
     public void Serialize_OnlyAddsPersistentProperties ()
     {
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Ceo));
+      var typeDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Ceo));
       var propertySerializerMock = new Mock<IPropertySerializer>(MockBehavior.Strict);
 
       propertySerializerMock
@@ -103,7 +103,7 @@ public void Serialize_OnlyAddsPersistentProperties ()
 
       var tableSerializer = new TableSerializer(propertySerializerMock.Object);
 
-      tableSerializer.Serialize(classDefinition).ToArray();
+      tableSerializer.Serialize(typeDefinition).ToArray();
       propertySerializerMock.Verify();
     }
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/ClassSerializerTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/TypeSerializerTest.cs
similarity index 66%
rename from Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/ClassSerializerTest.cs
rename to Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/TypeSerializerTest.cs
index 53da8e5ac0..b38ab10cd6 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/ClassSerializerTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/MappingExport/TypeSerializerTest.cs
@@ -26,7 +26,7 @@
 namespace Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.MappingExport
 {
   [TestFixture]
-  public class ClassSerializerTest : SchemaGenerationTestBase
+  public class TypeSerializerTest : SchemaGenerationTestBase
   {
 
     public override void SetUp ()
@@ -37,9 +37,9 @@ public override void SetUp ()
     [Test]
     public void Serialize_AddsIdAttribute ()
     {
-      var classSerializer = new ClassSerializer(new Mock<ITableSerializer>().Object);
+      var typeSerializer = new TypeSerializer(new Mock<ITableSerializer>().Object);
       var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(ClassWithAllDataTypes));
-      var actual = classSerializer.Serialize(classDefinition);
+      var actual = typeSerializer.Serialize(classDefinition);
 
       Assert.That(actual.Name.LocalName, Is.EqualTo("class"));
       Assert.That(actual.Attributes().Select(a => a.Name.LocalName), Contains.Item("id"));
@@ -49,9 +49,9 @@ public void Serialize_AddsIdAttribute ()
     [Test]
     public void Serialize_AddsBaseClassAttribute ()
     {
-      var classSerializer = new ClassSerializer(new Mock<ITableSerializer>().Object);
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(DerivedAbstractClass));
-      var actual = classSerializer.Serialize(classDefinition);
+      var typeSerializer = new TypeSerializer(new Mock<ITableSerializer>().Object);
+      var classDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(DerivedAbstractClass));
+      var actual = typeSerializer.Serialize(classDefinition);
 
       Assert.That(actual.Attributes().Select(a => a.Name.LocalName), Contains.Item("baseClass"));
       Assert.That(actual.Attribute("baseClass").Value, Is.EqualTo("AbstractClass"));
@@ -60,9 +60,9 @@ public void Serialize_AddsBaseClassAttribute ()
     [Test]
     public void Serialize_ClassHasNoBaseClass_DoesNotAddAttribute ()
     {
-      var classSerializer = new ClassSerializer(new Mock<ITableSerializer>().Object);
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Ceo));
-      var actual = classSerializer.Serialize(classDefinition);
+      var typeSerializer = new TypeSerializer(new Mock<ITableSerializer>().Object);
+      var classDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Ceo));
+      var actual = typeSerializer.Serialize(classDefinition);
 
       Assert.That(actual.Attributes().Select(a => a.Name.LocalName).Contains("baseClass"), Is.False);
     }
@@ -70,9 +70,9 @@ public void Serialize_ClassHasNoBaseClass_DoesNotAddAttribute ()
     [Test]
     public void Serialize_AddsAbstractAttribute ()
     {
-      var classSerializer = new ClassSerializer(new Mock<ITableSerializer>().Object);
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Ceo));
-      var actual = classSerializer.Serialize(classDefinition);
+      var typeSerializer = new TypeSerializer(new Mock<ITableSerializer>().Object);
+      var classDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Ceo));
+      var actual = typeSerializer.Serialize(classDefinition);
 
       Assert.That(actual.Attributes().Select(a => a.Name.LocalName), Contains.Item("isAbstract"));
       Assert.That(actual.Attribute("isAbstract").Value, Is.EqualTo("false"));
@@ -81,9 +81,9 @@ public void Serialize_AddsAbstractAttribute ()
     [Test]
     public void Serialize_AddsAbstractAttribute_AbstractClass ()
     {
-      var classSerializer = new ClassSerializer(new Mock<ITableSerializer>().Object);
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(DerivedAbstractClass));
-      var actual = classSerializer.Serialize(classDefinition);
+      var typeSerializer = new TypeSerializer(new Mock<ITableSerializer>().Object);
+      var classDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(DerivedAbstractClass));
+      var actual = typeSerializer.Serialize(classDefinition);
 
       Assert.That(actual.Attributes().Select(a => a.Name.LocalName), Contains.Item("isAbstract"));
       Assert.That(actual.Attribute("isAbstract").Value, Is.EqualTo("true"));
@@ -93,9 +93,9 @@ public void Serialize_AddsAbstractAttribute_AbstractClass ()
     public void Serialize_DoesNotExportTablesForAbstractNonInstantiableClasses ()
     {
       var tableSerializerStub = new Mock<ITableSerializer>();
-      var classSerializer = new ClassSerializer(tableSerializerStub.Object);
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(AbstractWithoutConcreteClass));
-      classSerializer.Serialize(classDefinition);
+      var typeSerializer = new TypeSerializer(tableSerializerStub.Object);
+      var classDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(AbstractWithoutConcreteClass));
+      typeSerializer.Serialize(classDefinition);
 
       tableSerializerStub.Verify(_ => _.Serialize(classDefinition), Times.Never());
     }
@@ -103,14 +103,14 @@ public void Serialize_DoesNotExportTablesForAbstractNonInstantiableClasses ()
     [Test]
     public void Serialize_AddsTableElements ()
     {
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Ceo));
+      var classDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Ceo));
       var tableSerializerMock = new Mock<ITableSerializer>();
       var expected1 = new XElement("property1");
 
       tableSerializerMock.Setup(_ => _.Serialize(classDefinition)).Returns(new [] { expected1 }).Verifiable();
-      var classSerializer = new ClassSerializer(tableSerializerMock.Object);
+      var typeSerializer = new TypeSerializer(tableSerializerMock.Object);
 
-      var actual = classSerializer.Serialize(classDefinition);
+      var actual = typeSerializer.Serialize(classDefinition);
       tableSerializerMock.Verify();
 
       Assert.That(actual.Elements().Count(), Is.EqualTo(1));
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/DataStoragePropertyDefinitionFactoryTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/DataStoragePropertyDefinitionFactoryTest.cs
index 082029cf34..e101e4eb5b 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/DataStoragePropertyDefinitionFactoryTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/DataStoragePropertyDefinitionFactoryTest.cs
@@ -95,7 +95,7 @@ public void CreateStoragePropertyDefinition_Value_NonObjectID ()
     [Test]
     public void CreateStoragePropertyDefinition_Value_ObjectID ()
     {
-      var expectedClassDefinition = GetTypeDefinition(typeof(Order));
+      var expectedClassDefinition = GetClassDefinition(typeof(Order));
       _relationPropertyFactoryMock
           .Setup(mock => mock.CreateStoragePropertyDefinition(expectedClassDefinition, "Value", "ValueClassID"))
           .Returns(_fakeStoragePropertyDefinition.Object)
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ForeignKeyConstraintDefinitionFactoryTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ForeignKeyConstraintDefinitionFactoryTest.cs
index 37088adb16..af0d2c401b 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ForeignKeyConstraintDefinitionFactoryTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ForeignKeyConstraintDefinitionFactoryTest.cs
@@ -58,8 +58,8 @@ public override void SetUp ()
     [Test]
     public void CreateForeignKeyConstraints ()
     {
-      var orderClassDefinition = Configuration.GetTypeDefinition(typeof(Order));
-      var customerClassDefintion = Configuration.GetTypeDefinition(typeof(Customer));
+      var orderClassDefinition = Configuration.GetClassDefinition(typeof(Order));
+      var customerClassDefintion = Configuration.GetClassDefinition(typeof(Customer));
 
       _infrastructureStoragePropertyDefintionProviderMock
           .Setup(mock => mock.GetObjectIDStoragePropertyDefinition())
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/RdbmsPersistenceModelLoaderTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/RdbmsPersistenceModelLoaderTest.cs
index 1ead199bd0..20a0619dc1 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/RdbmsPersistenceModelLoaderTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/RdbmsPersistenceModelLoaderTest.cs
@@ -116,7 +116,7 @@ public void CreatePersistenceMappingValidator ()
       Assert.That(validator.ValidationRules[2], Is.TypeOf(typeof(ClassAboveTableIsAbstractValidationRule)));
       Assert.That(validator.ValidationRules[3], Is.TypeOf(typeof(ColumnNamesAreUniqueWithinInheritanceTreeValidationRule)));
       Assert.That(validator.ValidationRules[4], Is.TypeOf(typeof(PropertyTypeIsSupportedByStorageProviderValidationRule)));
-      Assert.That(validator.ValidationRules[5], Is.TypeOf(typeof(RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRule)));
+      Assert.That(validator.ValidationRules[5], Is.TypeOf(typeof(RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRule)));
     }
 
     [Test]
@@ -255,7 +255,8 @@ public void ApplyPersistenceModelToHierarchy_Throws_WhenExistingEntityDefinition
           () => _rdbmsPersistenceModelLoader.ApplyPersistenceModelToHierarchy(_testModel.DerivedDerivedClassDefinition),
           Throws.InvalidOperationException
               .With.Message.EqualTo(
-                  "The storage entity definition of class 'Derived2Class' does not implement interface 'IRdbmsStorageEntityDefinition'."));
+                  "The storage entity definition of type 'Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.Model.RdbmsPersistenceModelLoaderTestDomain.Derived2Class' "
+                  + "does not implement interface 'IRdbmsStorageEntityDefinition'."));
     }
 
     [Test]
@@ -267,7 +268,9 @@ public void ApplyPersistenceModelToHierarchy_Throws_WhenExistingPropertyDefiniti
           () => _rdbmsPersistenceModelLoader.ApplyPersistenceModelToHierarchy(_testModel.DerivedDerivedClassDefinition),
           Throws.InvalidOperationException
               .With.Message.EqualTo(
-                  "The property definition 'DerivedDerivedProperty' of class 'DerivedDerivedClass' does not implement interface 'IRdbmsStoragePropertyDefinition'."));
+                  "The property definition 'DerivedDerivedProperty' of type "
+                  + "'Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.Model.RdbmsPersistenceModelLoaderTestDomain.DerivedDerivedClass' "
+                  + "does not implement interface 'IRdbmsStoragePropertyDefinition'."));
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ReflectionBasedStorageNameProviderTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ReflectionBasedStorageNameProviderTest.cs
index c974dc6705..69faa94767 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ReflectionBasedStorageNameProviderTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ReflectionBasedStorageNameProviderTest.cs
@@ -98,7 +98,7 @@ public void GetViewName ()
     public void GetColumnName_PropertyWithIStorageSpecificIdentifierAttribute_ReturnsNameFromAttribute ()
     {
       var classWithAllDataTypesDefinition =
-          ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithAllDataTypes), baseClass: null);
+          TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(ClassWithAllDataTypes), baseClass: null);
       var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(
           classWithAllDataTypesDefinition, typeof(ClassWithAllDataTypes), "BooleanProperty");
 
@@ -110,9 +110,9 @@ public void GetColumnName_PropertyWithIStorageSpecificIdentifierAttribute_Return
     [Test]
     public void GetColumnName_PropertyWithoutIStorageSpecificIdentifierAttribute_ReturnsPropertyName ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Distributor), baseClass: null);
-      classDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(classDefinition, typeof(Distributor), "NumberOfShops");
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Distributor), baseClass: null);
+      typeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(typeDefinition, typeof(Distributor), "NumberOfShops");
 
       var result = _provider.GetColumnName(propertyDefinition);
 
@@ -122,8 +122,8 @@ public void GetColumnName_PropertyWithoutIStorageSpecificIdentifierAttribute_Ret
     [Test]
     public void GetRelationColumnName ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(FileSystemItem), baseClass: null);
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(classDefinition, typeof(FileSystemItem), "ParentFolder");
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(FileSystemItem), baseClass: null);
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(typeDefinition, typeof(FileSystemItem), "ParentFolder");
       var relationDefinition = new RelationEndPointDefinition(propertyDefinition, true);
 
       var result = _provider.GetRelationColumnName(relationDefinition);
@@ -134,9 +134,9 @@ public void GetRelationColumnName ()
     [Test]
     public void GetRelationColumnName_PropertyWithIStorageSpecificIdentifierAttribute_ReturnsNameFromAttribute ()
     {
-      var classDefinition =
-          ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(FileSystemItem), baseClass: null);
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(classDefinition, typeof(FileSystemItem), "ParentFolder2");
+      var typeDefinition =
+          TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(FileSystemItem), baseClass: null);
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(typeDefinition, typeof(FileSystemItem), "ParentFolder2");
       var relationDefinition = new RelationEndPointDefinition(propertyDefinition, true);
 
       var result = _provider.GetRelationColumnName(relationDefinition);
@@ -147,8 +147,8 @@ public void GetRelationColumnName_PropertyWithIStorageSpecificIdentifierAttribut
     [Test]
     public void GetRelationClassIDColumnName ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(FileSystemItem), baseClass: null);
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(classDefinition, typeof(FileSystemItem), "ParentFolder");
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(FileSystemItem), baseClass: null);
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForRealPropertyInfo(typeDefinition, typeof(FileSystemItem), "ParentFolder");
       var relationDefinition = new RelationEndPointDefinition(propertyDefinition, true);
 
       var result = _provider.GetRelationClassIDColumnName(relationDefinition);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/RelationStoragePropertyDefinitionFactoryTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/RelationStoragePropertyDefinitionFactoryTest.cs
index 1016f3a675..bc089ba305 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/RelationStoragePropertyDefinitionFactoryTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/RelationStoragePropertyDefinitionFactoryTest.cs
@@ -57,7 +57,7 @@ public override void SetUp ()
     public void CreateStoragePropertyDefinition_RelationToClassDefinitionWithoutHierarchy ()
     {
       var endPointDefinition = GetNonVirtualEndPointDefinition(typeof(ClassWithManySideRelationProperties), "BidirectionalOneToOne");
-      var oppositeClassDefinition = endPointDefinition.GetOppositeEndPointDefinition().ClassDefinition;
+      var oppositeClassDefinition = endPointDefinition.GetOppositeEndPointDefinition().TypeDefinition;
       Assert.That(oppositeClassDefinition.IsPartOfInheritanceHierarchy, Is.False);
 
       _storageTypeInformationProviderStrictMock
@@ -96,14 +96,14 @@ public void CreateStoragePropertyDefinition_RelationToClassDefinitionWithoutHier
 
       Assert.That(
           objectIDWithoutClassIDStorageProperty.ClassDefinition,
-          Is.SameAs(endPointDefinition.GetOppositeEndPointDefinition().ClassDefinition));
+          Is.SameAs(endPointDefinition.GetOppositeEndPointDefinition().TypeDefinition));
     }
 
     [Test]
     public void CreateStoragePropertyDefinition_RelationToClassDefinitionWithoutHierarchy_WithForceClassIDTrue ()
     {
       var endPointDefinition = GetNonVirtualEndPointDefinition(typeof(ClassWithManySideRelationProperties), "BidirectionalOneToOne");
-      Assert.That(endPointDefinition.GetOppositeEndPointDefinition().ClassDefinition.IsPartOfInheritanceHierarchy, Is.False);
+      Assert.That(endPointDefinition.GetOppositeEndPointDefinition().TypeDefinition.IsPartOfInheritanceHierarchy, Is.False);
 
       _storageTypeInformationProviderStrictMock
           .Setup(mock => mock.GetStorageTypeForID(true))
@@ -124,7 +124,7 @@ public void CreateStoragePropertyDefinition_RelationToClassDefinitionWithoutHier
           .Verifiable();
 
       _storageSettingsStub
-          .Setup(stub => stub.GetStorageProviderDefinition(endPointDefinition.GetOppositeEndPointDefinition().ClassDefinition))
+          .Setup(stub => stub.GetStorageProviderDefinition(endPointDefinition.GetOppositeEndPointDefinition().TypeDefinition))
           .Returns(_factory.StorageProviderDefinition);
 
       var factoryForcingClassID = new RelationStoragePropertyDefinitionFactory(TestDomainStorageProviderDefinition,
@@ -145,7 +145,7 @@ public void CreateStoragePropertyDefinition_RelationToClassDefinitionWithoutHier
     public void CreateStoragePropertyDefinition_RelationToClassWithInheritanceHierarchy ()
     {
       var relationEndPointDefinition = GetNonVirtualEndPointDefinition(typeof(Ceo), "Company");
-      Assert.That(relationEndPointDefinition.GetOppositeEndPointDefinition().ClassDefinition.IsPartOfInheritanceHierarchy, Is.True);
+      Assert.That(relationEndPointDefinition.GetOppositeEndPointDefinition().TypeDefinition.IsPartOfInheritanceHierarchy, Is.True);
 
       _storageTypeInformationProviderStrictMock
           .Setup(mock => mock.GetStorageTypeForID(true))
@@ -166,7 +166,7 @@ public void CreateStoragePropertyDefinition_RelationToClassWithInheritanceHierar
           .Verifiable();
 
       _storageSettingsStub
-          .Setup(stub => stub.GetStorageProviderDefinition(relationEndPointDefinition.GetOppositeClassDefinition()))
+          .Setup(stub => stub.GetStorageProviderDefinition(relationEndPointDefinition.GetOppositeTypeDefinition()))
           .Returns(_factory.StorageProviderDefinition);
 
       var result = _factory.CreateStoragePropertyDefinition(relationEndPointDefinition);
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/TableInheritanceStorageEntitiesIntegrationTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/TableInheritanceStorageEntitiesIntegrationTest.cs
index ac05cd3298..455d044daa 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/TableInheritanceStorageEntitiesIntegrationTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/TableInheritanceStorageEntitiesIntegrationTest.cs
@@ -16,6 +16,7 @@
 // 
 using System;
 using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
 using Remotion.Data.DomainObjects.Persistence.Rdbms.Model;
 using Remotion.Data.DomainObjects.UnitTests.TestDomain.TableInheritance;
 
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ValueStoragePropertyDefinitionFactoryTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ValueStoragePropertyDefinitionFactoryTest.cs
index 5bf756d7d8..df90a3a404 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ValueStoragePropertyDefinitionFactoryTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Building/ValueStoragePropertyDefinitionFactoryTest.cs
@@ -23,6 +23,7 @@
 using Remotion.Data.DomainObjects.UnitTests.Factories;
 using Remotion.Data.DomainObjects.UnitTests.Mapping;
 using Remotion.Data.DomainObjects.UnitTests.UnitTesting;
+using Remotion.Reflection;
 
 namespace Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.Model.Building
 {
@@ -53,8 +54,8 @@ public void SetUp ()
       _someClassDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
 
       _someClassDefinitionWithoutBaseClass = ClassDefinitionObjectMother.CreateClassDefinition();
-      _someClassDefinitionWithBaseClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "some", baseClass: _someClassDefinitionWithoutBaseClass);
-      _someClassDefinitionWithBaseBaseClass = ClassDefinitionObjectMother.CreateClassDefinition(id: "some", baseClass: _someClassDefinitionWithBaseClass);
+      _someClassDefinitionWithBaseClass = ClassDefinitionObjectMother.CreateClassDefinition(baseClass: _someClassDefinitionWithoutBaseClass);
+      _someClassDefinitionWithBaseBaseClass = ClassDefinitionObjectMother.CreateClassDefinition(baseClass: _someClassDefinitionWithBaseClass);
 
       _fakeStorageTypeInformation1 = StorageTypeInformationObjectMother.CreateStorageTypeInformation();
       _fakeStorageTypeInformation2 = StorageTypeInformationObjectMother.CreateStorageTypeInformation();
@@ -77,7 +78,7 @@ public void CreateStoragePropertyDefinition_PropertyDefinition_NotSupportedType
           result,
           Is.TypeOf<UnsupportedStoragePropertyDefinition>()
               .With.Property<UnsupportedStoragePropertyDefinition>(pd => pd.Message).EqualTo(
-                  "There was an error when retrieving storage type for property 'Test' (declaring class: '" + _someClassDefinition.ID + "'): Msg.")
+                  "There was an error when retrieving storage type for property 'Test' (declaring type: '" + _someClassDefinition.Type.GetFullNameSafe() + "'): Msg.")
               .And.Property<UnsupportedStoragePropertyDefinition>(pd => pd.PropertyType).EqualTo(typeof(string))
               .And.Property<UnsupportedStoragePropertyDefinition>(pd => pd.InnerException).SameAs(exception));
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/ObjectIDWithoutClassIDStoragePropertyDefinitionTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/ObjectIDWithoutClassIDStoragePropertyDefinitionTest.cs
index 25a8e3f52d..d43d7e89e8 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/ObjectIDWithoutClassIDStoragePropertyDefinitionTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/ObjectIDWithoutClassIDStoragePropertyDefinitionTest.cs
@@ -70,7 +70,7 @@ public void Initialization ()
     [Test]
     public void Initialization_WithAbstractClassDefinition ()
     {
-      var abstractClassDefinition = GetTypeDefinition(typeof(TIFileSystemItem));
+      var abstractClassDefinition = GetClassDefinition(typeof(TIFileSystemItem));
       Assert.That(abstractClassDefinition.IsAbstract, Is.True);
 
       Assert.That(
@@ -287,14 +287,14 @@ public void UnifyWithEquivalentProperties_ThrowsForDifferentStoragePropertyType
     [Test]
     public void UnifyWithEquivalentProperties_ThrowsForDifferentClassDefinitions ()
     {
-      var property2 = new ObjectIDWithoutClassIDStoragePropertyDefinition(_valuePropertyStub.Object, GetTypeDefinition(typeof(OrderItem)));
+      var property2 = new ObjectIDWithoutClassIDStoragePropertyDefinition(_valuePropertyStub.Object, GetClassDefinition(typeof(OrderItem)));
 
       Assert.That(
           () => _objectIDWithoutClassIDStoragePropertyDefinition.UnifyWithEquivalentProperties(new[] { property2 }),
           Throws.ArgumentException.With.ArgumentExceptionMessageEqualTo(
               "Only equivalent properties can be combined, but this property has class definition "
-              + "'Remotion.Data.DomainObjects.Mapping.ClassDefinition: Order', and the given property has "
-              + "class definition 'Remotion.Data.DomainObjects.Mapping.ClassDefinition: OrderItem'.", "equivalentProperties"));
+              + "'ClassDefinition: Order', and the given property has "
+              + "class definition 'ClassDefinition: OrderItem'.", "equivalentProperties"));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/ClassAboveTableIsAbstractValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/ClassAboveTableIsAbstractValidationRuleTest.cs
index e18532031f..70366eb82d 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/ClassAboveTableIsAbstractValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/ClassAboveTableIsAbstractValidationRuleTest.cs
@@ -15,6 +15,7 @@
 // along with re-motion; if not, see http://www.gnu.org/licenses.
 // 
 using System;
+using System.Linq;
 using Moq;
 using NUnit.Framework;
 using Remotion.Data.DomainObjects.Infrastructure;
@@ -25,6 +26,7 @@
 using Remotion.Data.DomainObjects.UnitTests.Mapping;
 using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation;
 using Remotion.Data.DomainObjects.UnitTests.Mapping.Validation;
+using Remotion.Reflection;
 
 namespace Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.Model.Validation
 {
@@ -54,11 +56,12 @@ public void SetUp ()
     [Test]
     public void ClassTypeUnresolved_UnionViewDefinition_NotAbstract ()
     {
-      var classDefinition = new ClassDefinitionWithUnresolvedClassType(
+      var classDefinition = new ClassDefinitionWithUnresolvedType(
           "NonAbstractClassHasEntityNameDomainObject",
           typeof(DerivedValidationDomainObjectClass),
           false,
           null,
+          Enumerable.Empty<InterfaceDefinition>(),
           new Mock<IPersistentMixinFinder>().Object,
           new Mock<IDomainObjectCreator>().Object);
       classDefinition.SetStorageEntity(_unionViewDefinition);
@@ -144,5 +147,14 @@ public void ClassTypeResolved_EmptyViewDefinition_NotAbstract ()
                             "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.DerivedValidationDomainObjectClass";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
     }
+
+    [Test]
+    public void IgnoresArgumentsOfTypeOtherThanClassDefinition ()
+    {
+      var typeDefinitionForUnresolvedRelationPropertyType = new TypeDefinitionForUnresolvedRelationPropertyType(typeof(string), new NullPropertyInformation());
+      var validationResult = _validationRule.Validate(typeDefinitionForUnresolvedRelationPropertyType);
+
+      AssertMappingValidationResult(validationResult, true, null);
+    }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/ColumnNamesAreUniqueWithinInheritanceTreeValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/ColumnNamesAreUniqueWithinInheritanceTreeValidationRuleTest.cs
index 6f0644c9b2..6019eaf7da 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/ColumnNamesAreUniqueWithinInheritanceTreeValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/ColumnNamesAreUniqueWithinInheritanceTreeValidationRuleTest.cs
@@ -43,9 +43,9 @@ public void SetUp ()
     {
       _validationRule = new ColumnNamesAreUniqueWithinInheritanceTreeValidationRule(new RdbmsPersistenceModelProvider());
       _baseOfBaseClass = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(BaseOfBaseValidationDomainObjectClass));
-      _derivedBaseClass1 = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(BaseValidationDomainObjectClass), baseClass: _baseOfBaseClass);
-      _derivedBaseClass2 = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(DerivedValidationDomainObjectClass), baseClass: _derivedBaseClass1);
-      _derivedClass = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(OtherDerivedValidationHierarchyClass), baseClass: _baseOfBaseClass);
+      _derivedBaseClass1 = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties(classType: typeof(BaseValidationDomainObjectClass), baseClass: _baseOfBaseClass);
+      _derivedBaseClass2 = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties(classType: typeof(DerivedValidationDomainObjectClass), baseClass: _derivedBaseClass1);
+      _derivedClass = ClassDefinitionObjectMother.CreateClassDefinitionWithDefaultProperties(classType: typeof(OtherDerivedValidationHierarchyClass), baseClass: _baseOfBaseClass);
 
       _baseOfBaseClass.SetDerivedClasses(new[] { _derivedBaseClass1, _derivedClass });
       _derivedBaseClass1.SetDerivedClasses(new[] { _derivedBaseClass2 });
@@ -82,7 +82,7 @@ public void InheritanceRoot_NonPersistentPropertiesWithSameStorageSpecificProper
     [Test]
     public void InheritanceRoot_PersistentPropertiesWithSameStorageSpecificPropertyNameInSameClass ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedValidationDomainObjectClass));
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixinsWithDefaultProperties(typeof(DerivedValidationDomainObjectClass));
       var propertyDefinition1 = CreatePersistentPropertyDefinition(
           classDefinition,
           "Property",
@@ -110,7 +110,7 @@ public void InheritanceRoot_PersistentPropertiesWithSameStorageSpecificPropertyN
     [Test]
     public void InheritanceRoot_PersistentPropertiesWithDifferentStorageSpecificPropertyNameInSameClass ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedValidationDomainObjectClass));
+      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixinsWithDefaultProperties(typeof(DerivedValidationDomainObjectClass));
 
       var propertyDefinition1 = CreatePersistentPropertyDefinition(
           classDefinition,
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/OnlyOneTablePerHierarchyValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/OnlyOneTablePerHierarchyValidationRuleTest.cs
index 82b1ae229f..68fb5e9fad 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/OnlyOneTablePerHierarchyValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/OnlyOneTablePerHierarchyValidationRuleTest.cs
@@ -22,6 +22,7 @@
 using Remotion.Data.DomainObjects.UnitTests.Mapping;
 using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation;
 using Remotion.Data.DomainObjects.UnitTests.Mapping.Validation;
+using Remotion.Reflection;
 
 namespace Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.Model.Validation
 {
@@ -119,5 +120,14 @@ public void HasBaseClassesAndHasTableDefinition_BaseOfBaseClassHasTableDefinitio
           + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.DerivedValidationDomainObjectClass";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
     }
+
+    [Test]
+    public void IgnoresArgumentsOfTypeOtherThanClassDefinition ()
+    {
+      var typeDefinitionForUnresolvedRelationPropertyType = new TypeDefinitionForUnresolvedRelationPropertyType(typeof(string), new NullPropertyInformation());
+      var validationResult = _validationRule.Validate(typeDefinitionForUnresolvedRelationPropertyType);
+
+      AssertMappingValidationResult(validationResult, true, null);
+    }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/PropertyTypeIsSupportedByStorageProviderValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/PropertyTypeIsSupportedByStorageProviderValidationRuleTest.cs
index 27c3e603fa..faa8e966db 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/PropertyTypeIsSupportedByStorageProviderValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/PropertyTypeIsSupportedByStorageProviderValidationRuleTest.cs
@@ -31,20 +31,20 @@ namespace Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.Model.Validati
   public class PropertyTypeIsSupportedByStorageProviderValidationRuleTest : ValidationRuleTestBase
   {
     private PropertyTypeIsSupportedByStorageProviderValidationRule _validationRule;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     [SetUp]
     public void SetUp ()
     {
       _validationRule = new PropertyTypeIsSupportedByStorageProviderValidationRule();
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(DerivedValidationDomainObjectClass));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithMixinsAndDefaultProperties(typeof(DerivedValidationDomainObjectClass));
     }
 
     [Test]
     public void PropertyWithStorageClassNone ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("PropertyWithStorageClassNone")),
           "PropertyWithStorageClassNone",
           false,
@@ -53,10 +53,10 @@ public void PropertyWithStorageClassNone ()
           StorageClass.None,
           null);
       propertyDefinition.SetStorageProperty(SimpleStoragePropertyDefinitionObjectMother.CreateStorageProperty("PropertyWithStorageClassNone"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -65,7 +65,7 @@ public void PropertyWithStorageClassNone ()
     public void PropertyWithStorageClassPersistent_StoragePropertyIsNotSet ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("PropertyWithTypeObjectWithStorageClassPersistent")),
           "PropertyWithTypeObjectWithStorageClassPersistent",
           false,
@@ -73,10 +73,10 @@ public void PropertyWithStorageClassPersistent_StoragePropertyIsNotSet ()
           null,
           StorageClass.Persistent,
           null);
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -85,7 +85,7 @@ public void PropertyWithStorageClassPersistent_StoragePropertyIsNotSet ()
     public void PropertyWithStorageClassPersistent_SupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("PropertyWithStorageClassPersistent")),
           "PropertyWithStorageClassPersistent",
           false,
@@ -94,10 +94,10 @@ public void PropertyWithStorageClassPersistent_SupportedType ()
           StorageClass.Persistent,
           null);
       propertyDefinition.SetStorageProperty(SimpleStoragePropertyDefinitionObjectMother.CreateStorageProperty("PropertyWithStorageClassPersistent"));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       AssertMappingValidationResult(validationResult, true, null);
     }
@@ -106,7 +106,7 @@ public void PropertyWithStorageClassPersistent_SupportedType ()
     public void PropertyWithStorageClassPersistent_UnsupportedType ()
     {
       var propertyDefinition = new PropertyDefinition(
-          _classDefinition,
+          _typeDefinition,
           PropertyInfoAdapter.Create(typeof(DerivedValidationDomainObjectClass).GetProperty("PropertyWithTypeObjectWithStorageClassPersistent")),
           "PropertyWithTypeObjectWithStorageClassPersistent",
           false,
@@ -115,10 +115,10 @@ public void PropertyWithStorageClassPersistent_UnsupportedType ()
           StorageClass.Persistent,
           null);
       propertyDefinition.SetStorageProperty(new UnsupportedStoragePropertyDefinition(typeof(int), "Message", null));
-      _classDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
-      _classDefinition.SetReadOnly();
+      _typeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection(new[]{propertyDefinition}, true));
+      _typeDefinition.SetReadOnly();
 
-      var validationResult = _validationRule.Validate(_classDefinition);
+      var validationResult = _validationRule.Validate(_typeDefinition);
 
       var expectedMessage = "The property type 'Object' is not supported by this storage provider. Message\r\n\r\n"
         +"Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.DerivedValidationDomainObjectClass\r\n"
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/TableNamesAreDistinctWithinConcreteTableInheritanceHierarchyValidationRuleTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/TableNamesAreDistinctWithinConcreteTableInheritanceHierarchyValidationRuleTest.cs
index 581bec87a3..9c064379a6 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/TableNamesAreDistinctWithinConcreteTableInheritanceHierarchyValidationRuleTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/Model/Validation/TableNamesAreDistinctWithinConcreteTableInheritanceHierarchyValidationRuleTest.cs
@@ -22,6 +22,7 @@
 using Remotion.Data.DomainObjects.UnitTests.Mapping;
 using Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation;
 using Remotion.Data.DomainObjects.UnitTests.Mapping.Validation;
+using Remotion.Reflection;
 
 namespace Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.Model.Validation
 {
@@ -139,5 +140,14 @@ public void InheritanceRoot_SameTableNameInDerivedDerivedClass ()
           + "Declaring type: Remotion.Data.DomainObjects.UnitTests.Mapping.TestDomain.Validation.BaseOfBaseValidationDomainObjectClass";
       AssertMappingValidationResult(validationResult, false, expectedMessage);
     }
+
+    [Test]
+    public void IgnoresArgumentsOfTypeOtherThanClassDefinition ()
+    {
+      var typeDefinitionForUnresolvedRelationPropertyType = new TypeDefinitionForUnresolvedRelationPropertyType(typeof(string), new NullPropertyInformation());
+      var validationResult = _validationRule.Validate(typeDefinitionForUnresolvedRelationPropertyType);
+
+      AssertMappingValidationResult(validationResult, true, null);
+    }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/RdbmsPersistenceModelProviderTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/RdbmsPersistenceModelProviderTest.cs
index 4e0543f38d..6092f5770c 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/RdbmsPersistenceModelProviderTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/RdbmsPersistenceModelProviderTest.cs
@@ -29,23 +29,23 @@ namespace Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms
   public class RdbmsPersistenceModelProviderTest : StandardMappingTest
   {
     private RdbmsPersistenceModelProvider _provider;
-    private ClassDefinition _classDefinition;
+    private TypeDefinition _typeDefinition;
 
     public override void SetUp ()
     {
       base.SetUp();
 
       _provider = new RdbmsPersistenceModelProvider();
-      _classDefinition = ClassDefinitionObjectMother.CreateClassDefinition("Order", typeof(Order));
+      _typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition("Order", typeof(Order));
     }
 
     [Test]
     public void GetEntityDefinition ()
     {
       var entityDefinition = new Mock<IRdbmsStorageEntityDefinition>();
-      _classDefinition.SetStorageEntity(entityDefinition.Object);
+      _typeDefinition.SetStorageEntity(entityDefinition.Object);
 
-      var result = _provider.GetEntityDefinition(_classDefinition);
+      var result = _provider.GetEntityDefinition(_typeDefinition);
 
       Assert.That(result, Is.SameAs(entityDefinition.Object));
     }
@@ -53,27 +53,29 @@ public void GetEntityDefinition ()
     [Test]
     public void GetEntityDefinition_EmptyViewDefinition ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition("Order", classType: typeof(Order), baseClass: null);
-      Assert.That(classDefinition.HasStorageEntityDefinitionBeenSet, Is.False);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition("Order", classType: typeof(Order), baseClass: null);
+      Assert.That(typeDefinition.HasStorageEntityDefinitionBeenSet, Is.False);
       Assert.That(
-          () => _provider.GetEntityDefinition(classDefinition),
+          () => _provider.GetEntityDefinition(typeDefinition),
           Throws.InstanceOf<RdbmsProviderException>()
               .With.Message.EqualTo(
-                  "The Rdbms provider classes require a storage definition object of type 'IRdbmsStorageEntityDefinition' for class-definition 'Order', "
-                  + "but that class has no storage definition object."));
+                  "The Rdbms provider classes require a storage definition object of type 'IRdbmsStorageEntityDefinition' for type definition "
+                  + "'Remotion.Data.DomainObjects.UnitTests.TestDomain.Order', "
+                  + "but that type definition has no storage definition object."));
     }
 
     [Test]
     public void GetEntityDefinition_WrongEntityDefinition ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition("Order", typeof(Order));
-      classDefinition.SetStorageEntity(new FakeStorageEntityDefinition(TestDomainStorageProviderDefinition, "Test"));
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition("Order", typeof(Order));
+      typeDefinition.SetStorageEntity(new FakeStorageEntityDefinition(TestDomainStorageProviderDefinition, "Test"));
       Assert.That(
-          () => _provider.GetEntityDefinition(classDefinition),
+          () => _provider.GetEntityDefinition(typeDefinition),
           Throws.InstanceOf<RdbmsProviderException>()
               .With.Message.EqualTo(
-                  "The Rdbms provider classes require a storage definition object of type 'IRdbmsStorageEntityDefinition' for class-definition 'Order', "
-                  + "but that class has a storage definition object of type 'FakeStorageEntityDefinition'."));
+                  "The Rdbms provider classes require a storage definition object of type 'IRdbmsStorageEntityDefinition' for type definition "
+                  + "'Remotion.Data.DomainObjects.UnitTests.TestDomain.Order', "
+                  + "but that type definition has a storage definition object of type 'FakeStorageEntityDefinition'."));
     }
 
     [Test]
@@ -91,20 +93,20 @@ public void GetStoragePropertyDefinition ()
     [Test]
     public void GetStoragePropertyDefinition_NoDefinition ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_classDefinition, "OrderNumber");
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_typeDefinition, "OrderNumber");
       Assert.That(propertyDefinition.HasStoragePropertyDefinitionBeenSet, Is.False);
       Assert.That(
           () => _provider.GetStoragePropertyDefinition(propertyDefinition),
           Throws.InstanceOf<MappingException>()
               .With.Message.EqualTo(
                   "The Rdbms provider classes require a storage definition object of type 'IRdbmsStoragePropertyDefinition' for property 'OrderNumber' of "
-                  + "class-definition 'Order', but that property has no storage definition object."));
+                  + "class-definition 'Remotion.Data.DomainObjects.UnitTests.TestDomain.Order', but that property has no storage definition object."));
     }
 
     [Test]
     public void GetStoragePropertyDefinition_NoRdbmsDefinition ()
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_classDefinition, "OrderNumber");
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(_typeDefinition, "OrderNumber");
       var storagePropertyDefinition = new FakeStoragePropertyDefinition("Test");
       propertyDefinition.SetStorageProperty(storagePropertyDefinition);
       Assert.That(
@@ -112,7 +114,8 @@ public void GetStoragePropertyDefinition_NoRdbmsDefinition ()
           Throws.InstanceOf<MappingException>()
               .With.Message.EqualTo(
                   "The Rdbms provider classes require a storage definition object of type 'IRdbmsStoragePropertyDefinition' for property 'OrderNumber' of "
-                  + "class-definition 'Order', but that property has a storage definition object of type 'FakeStoragePropertyDefinition'."));
+                  + "class-definition 'Remotion.Data.DomainObjects.UnitTests.TestDomain.Order', "
+                  + "but that property has a storage definition object of type 'FakeStoragePropertyDefinition'."));
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/RdbmsProviderTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/RdbmsProviderTest.cs
index a1e6bd9064..e16b6b2f80 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/RdbmsProviderTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/RdbmsProviderTest.cs
@@ -521,7 +521,7 @@ public void LoadDataContainersByRelatedID_ClassDefinitionWithDifferentStoragePro
       Assert.That(
           () => providerWithDifferentID.LoadDataContainersByRelatedID(relationEndPointDefinition, null, objectID),
           Throws.Exception.TypeOf<ArgumentException>().With.ArgumentExceptionMessageEqualTo(
-              "The StorageProvider 'TestDomain' of the provided ClassDefinition does not match with this StorageProvider 'Test'.", "classDefinition"));
+              "The StorageProvider 'TestDomain' of the provided TypeDefinition does not match with this StorageProvider 'Test'.", "relationEndPointDefinition.TypeDefinition"));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderCreateNewObjectIDTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderCreateNewObjectIDTest.cs
index 118cc2e72e..6b3a84128f 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderCreateNewObjectIDTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderCreateNewObjectIDTest.cs
@@ -28,7 +28,7 @@ public class SqlProviderCreateNewObjectIDTest : SqlProviderBaseTest
     [Test]
     public void CreateNewObjectID ()
     {
-      ClassDefinition orderClass = MappingConfiguration.Current.GetTypeDefinition(typeof(Order));
+      ClassDefinition orderClass = MappingConfiguration.Current.GetClassDefinition(typeof(Order));
       var newObjectID = Provider.CreateNewObjectID(orderClass);
 
       Assert.IsNotNull(newObjectID, "ObjectID of new DataContainer.");
@@ -39,13 +39,13 @@ public void CreateNewObjectID ()
     [Test]
     public void CreateNewObjectID_ClassDefinitionOfOtherStorageProvider ()
     {
-      ClassDefinition classDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(Official));
+      ClassDefinition classDefinition = MappingConfiguration.Current.GetClassDefinition(typeof(Official));
       Assert.That(
           () => Provider.CreateNewObjectID(classDefinition),
           Throws.ArgumentException
               .With.ArgumentExceptionMessageEqualTo(
-                  "The StorageProvider 'UnitTestStorageProviderStub' of the provided ClassDefinition does not match with this StorageProvider 'TestDomain'.",
-                  "classDefinition"));
+                  "The StorageProvider 'UnitTestStorageProviderStub' of the provided TypeDefinition does not match with this StorageProvider 'TestDomain'.",
+                  "typeDefinition"));
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderGeneratedSqlTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderGeneratedSqlTest.cs
index 4ae726e39f..0ed6d01727 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderGeneratedSqlTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderGeneratedSqlTest.cs
@@ -232,7 +232,7 @@ public void ExecuteScalarQuery ()
     public void Save ()
     {
       var newGuid = new Guid("322D1DCB-19E4-49BA-90AB-7F5C9C8126E8");
-      var newDataContainer = DataContainer.CreateNew(new ObjectID(Configuration.GetTypeDefinition(typeof(Employee)), newGuid));
+      var newDataContainer = DataContainer.CreateNew(new ObjectID(Configuration.GetClassDefinition(typeof(Employee)), newGuid));
       SetPropertyValue(newDataContainer, typeof(Employee), "Name", "");
       var changedDataContainer = _testHelper.LoadDataContainerInSeparateProvider(DomainObjectIDs.Employee1);
       SetPropertyValue(changedDataContainer, typeof(Employee), "Name", "George");
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderSaveNewTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderSaveNewTest.cs
index 3e4e2d278a..f96ebb7308 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderSaveNewTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderSaveNewTest.cs
@@ -375,7 +375,7 @@ private DataContainer ReloadDataContainer (ObjectID id)
 
     private DataContainer CreateNewDataContainer (Type type)
     {
-      return DataContainer.CreateNew(Provider.CreateNewObjectID(MappingConfiguration.Current.GetTypeDefinition(type)));
+      return DataContainer.CreateNew(Provider.CreateNewObjectID(MappingConfiguration.Current.GetClassDefinition(type)));
     }
 
   }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderTableInheritanceGeneratedSqlTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderTableInheritanceGeneratedSqlTest.cs
index 4bb5a4cd3c..593e517a26 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderTableInheritanceGeneratedSqlTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/IntegrationTests/SqlProviderTableInheritanceGeneratedSqlTest.cs
@@ -119,7 +119,7 @@ public void LoadDataContainersByRelatedID_WithSortExpression ()
     [Test]
     public void LoadDataContainersByRelatedID_WithEmptyResult ()
     {
-      var newObjectID = _testHelper.Provider.CreateNewObjectID(Configuration.GetTypeDefinition(typeof(TIClient)));
+      var newObjectID = _testHelper.Provider.CreateNewObjectID(Configuration.GetClassDefinition(typeof(TIClient)));
 
       var sequence = new VerifiableSequence();
       _testHelper.ExpectExecuteReader(
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Model/Building/SqlFulltextQueryCompatibleStringPropertyStorageTypeInformationProviderDecoratorTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Model/Building/SqlFulltextQueryCompatibleStringPropertyStorageTypeInformationProviderDecoratorTest.cs
index 9dc52bb753..5c09f5bd0c 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Model/Building/SqlFulltextQueryCompatibleStringPropertyStorageTypeInformationProviderDecoratorTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Model/Building/SqlFulltextQueryCompatibleStringPropertyStorageTypeInformationProviderDecoratorTest.cs
@@ -289,9 +289,9 @@ public void GetStorageType_ForValue_WithoutStorageTypeLength_ReturnsDecoratedSto
 
     private PropertyDefinition CreatePropertyDefinition ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition();
       return PropertyDefinitionObjectMother.CreateForFakePropertyInfo(
-          classDefinition,
+          typeDefinition,
           "Name",
           false,
           typeof(object),
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Model/Building/SqlStorageTypeInformationProviderTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Model/Building/SqlStorageTypeInformationProviderTest.cs
index 62c1239f2d..33f4071061 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Model/Building/SqlStorageTypeInformationProviderTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Model/Building/SqlStorageTypeInformationProviderTest.cs
@@ -703,9 +703,9 @@ private void CheckGetStorageType_ForProperty (
 
     private PropertyDefinition CreatePropertyDefinition (Type propertyType, bool isNullable, int? maxLength = null)
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition();
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition();
       return PropertyDefinitionObjectMother.CreateForFakePropertyInfo(
-          classDefinition,
+          typeDefinition,
           "Name",
           false,
           propertyType,
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/SchemaGeneration/RdbmsStorageExtendedEntityDefinitionProvider.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/SchemaGeneration/RdbmsStorageExtendedEntityDefinitionProvider.cs
index 0aa781a938..be864be058 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/SchemaGeneration/RdbmsStorageExtendedEntityDefinitionProvider.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/SchemaGeneration/RdbmsStorageExtendedEntityDefinitionProvider.cs
@@ -29,9 +29,9 @@ namespace Remotion.Data.DomainObjects.UnitTests.Persistence.Rdbms.SqlServer.Sche
 {
   public class RdbmsStorageExtendedEntityDefinitionProvider : IRdbmsStorageEntityDefinitionProvider
   {
-    public IEnumerable<IRdbmsStorageEntityDefinition> GetEntityDefinitions (IEnumerable<ClassDefinition> classDefinitions)
+    public IEnumerable<IRdbmsStorageEntityDefinition> GetEntityDefinitions (IEnumerable<TypeDefinition> typeDefinitions)
     {
-      var entityDefinitions = new RdbmsStorageEntityDefinitionProvider().GetEntityDefinitions(classDefinitions).ToList();
+      var entityDefinitions = new RdbmsStorageEntityDefinitionProvider().GetEntityDefinitions(typeDefinitions).ToList();
 
       var tableDefinitions = entityDefinitions.OfType<TableDefinition>().ToList();
       if (tableDefinitions.Count() > 0)
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Sql2016/SqlStorageObjectFactoryTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Sql2016/SqlStorageObjectFactoryTest.cs
index 57175c5e25..a88b917cfb 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Sql2016/SqlStorageObjectFactoryTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/SqlServer/Sql2016/SqlStorageObjectFactoryTest.cs
@@ -561,8 +561,8 @@ public void CreateStorageProviderSerializer ()
       var storageProviderSerializer = testableSqlProviderFactory.CreateStorageProviderSerializer(enumSerializerStub.Object);
       Assert.That(storageProviderSerializer, Is.InstanceOf<StorageProviderSerializer>());
       Assert.That(
-          ((StorageProviderSerializer)storageProviderSerializer).ClassSerializer,
-          Is.InstanceOf<ClassSerializer>());
+          ((StorageProviderSerializer)storageProviderSerializer).TypeSerializer,
+          Is.InstanceOf<TypeSerializer>());
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/StorageProviderCommands/Factories/RelationLookupCommandFactoryTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/StorageProviderCommands/Factories/RelationLookupCommandFactoryTest.cs
index 0ab6ac897c..961d210f28 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/StorageProviderCommands/Factories/RelationLookupCommandFactoryTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/Rdbms/StorageProviderCommands/Factories/RelationLookupCommandFactoryTest.cs
@@ -93,9 +93,9 @@ public override void SetUp ()
     [Test]
     public void CreateForRelationLookup_TableDefinition_NoSortExpression ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinitionWithTable(classType: typeof(Order), storageProviderDefinition: TestDomainStorageProviderDefinition);
-      var relationEndPointDefinition = CreateForeignKeyEndPointDefinition(classDefinition);
-      var oppositeTable = (TableDefinition)relationEndPointDefinition.ClassDefinition.StorageEntityDefinition;
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinitionWithTable(classType: typeof(Order), storageProviderDefinition: TestDomainStorageProviderDefinition);
+      var relationEndPointDefinition = CreateForeignKeyEndPointDefinition(typeDefinition);
+      var oppositeTable = (TableDefinition)relationEndPointDefinition.TypeDefinition.StorageEntityDefinition;
 
       _foreignKeyStoragePropertyDefinitionStrictMock.Setup(mock => mock.SplitValueForComparison(_foreignKeyValue)).Returns(_fakeComparedColumns).Verifiable();
 
@@ -103,7 +103,7 @@ public void CreateForRelationLookup_TableDefinition_NoSortExpression ()
       _dbCommandBuilderFactoryStrictMock
           .Setup(
               stub => stub.CreateForSelect(
-                  (TableDefinition)classDefinition.StorageEntityDefinition,
+                  (TableDefinition)typeDefinition.StorageEntityDefinition,
                   expectedSelectedColumns,
                   _fakeComparedColumns,
                   new OrderedColumn[0]))
@@ -308,55 +308,55 @@ private IStorageProviderCommand<TIn, IRdbmsProviderCommandExecutionContext> Chec
     }
 
     private SortedPropertySpecification CreateSortedPropertySpecification (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         SortOrder sortOrder,
         ColumnDefinition sortedColumn)
     {
       return CreateSortedPropertySpecification(
-          classDefinition,
+          typeDefinition,
           new SimpleStoragePropertyDefinition(typeof(int), sortedColumn),
           sortOrder);
     }
 
     private SortedPropertySpecification CreateSortedPropertySpecification (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         SortOrder sortOrder,
         ColumnDefinition sortedColumn1,
         ColumnDefinition sortedColumn2)
     {
       return CreateSortedPropertySpecification(
-          classDefinition,
+          typeDefinition,
           new ObjectIDStoragePropertyDefinition(
               new SimpleStoragePropertyDefinition(typeof(int), sortedColumn1), new SimpleStoragePropertyDefinition(typeof(int), sortedColumn2)),
           sortOrder);
     }
 
-    private RelationEndPointDefinition CreateForeignKeyEndPointDefinition (ClassDefinition classDefinition)
+    private RelationEndPointDefinition CreateForeignKeyEndPointDefinition (TypeDefinition typeDefinition)
     {
-      var idPropertyDefinition = CreateForeignKeyPropertyDefinition(classDefinition);
+      var idPropertyDefinition = CreateForeignKeyPropertyDefinition(typeDefinition);
       return new RelationEndPointDefinition(idPropertyDefinition, false);
     }
 
-    private PropertyDefinition CreateForeignKeyPropertyDefinition (ClassDefinition classDefinition)
+    private PropertyDefinition CreateForeignKeyPropertyDefinition (TypeDefinition typeDefinition)
     {
-      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(classDefinition, "OrderTicket");
+      var propertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo_ObjectID(typeDefinition, "OrderTicket");
       propertyDefinition.SetStorageProperty(_foreignKeyStoragePropertyDefinitionStrictMock.Object);
       return propertyDefinition;
     }
 
     private SortedPropertySpecification CreateSortedPropertySpecification (
-        ClassDefinition classDefinition, IStoragePropertyDefinition columnDefinition, SortOrder sortOrder)
+        TypeDefinition typeDefinition, IStoragePropertyDefinition columnDefinition, SortOrder sortOrder)
     {
-      var sortedPropertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(classDefinition);
+      var sortedPropertyDefinition = PropertyDefinitionObjectMother.CreateForFakePropertyInfo(typeDefinition);
       sortedPropertyDefinition.SetStorageProperty(columnDefinition);
       return new SortedPropertySpecification(sortedPropertyDefinition, sortOrder);
     }
 
-    private ClassDefinition CreateClassDefinition (IStorageEntityDefinition entityDefinition)
+    private TypeDefinition CreateClassDefinition (IStorageEntityDefinition entityDefinition)
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order), baseClass: null);
-      classDefinition.SetStorageEntity(entityDefinition);
-      return classDefinition;
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order), baseClass: null);
+      typeDefinition.SetStorageEntity(entityDefinition);
+      return typeDefinition;
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Persistence/StorageEntityBasedStorageProviderDefinitionFinderTest.cs b/Remotion/Data/DomainObjects.UnitTests/Persistence/StorageEntityBasedStorageProviderDefinitionFinderTest.cs
index d72be161b1..d1d536418d 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Persistence/StorageEntityBasedStorageProviderDefinitionFinderTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Persistence/StorageEntityBasedStorageProviderDefinitionFinderTest.cs
@@ -16,6 +16,7 @@
 // 
 using System;
 using NUnit.Framework;
+using Remotion.Data.DomainObjects.Mapping;
 using Remotion.Data.DomainObjects.Persistence;
 using Remotion.Data.DomainObjects.UnitTests.Mapping;
 using Remotion.Data.DomainObjects.UnitTests.TestDomain;
@@ -47,14 +48,14 @@ public void GetStorageProviderDefinition ()
     [Test]
     public void GetStorageProviderDefinition_NoStorageEntity ()
     {
-      var classDefinition = ClassDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order), baseClass: null);
+      var typeDefinition = TypeDefinitionObjectMother.CreateClassDefinition(classType: typeof(Order), baseClass: null);
 
       Assert.That(
-          () => _finder.GetStorageProviderDefinition(classDefinition, null),
-          Throws.InvalidOperationException.With.Message.EqualTo("Cannot obtain storage provider for ClassDefinitions without storage entities. "));
+          () => _finder.GetStorageProviderDefinition(typeDefinition, null),
+          Throws.InvalidOperationException.With.Message.EqualTo("Cannot obtain storage provider for TypeDefinitions without storage entities. "));
       Assert.That(
-          () => _finder.GetStorageProviderDefinition(classDefinition, "Context"),
-          Throws.InvalidOperationException.With.Message.EqualTo("Cannot obtain storage provider for ClassDefinitions without storage entities. Context"));
+          () => _finder.GetStorageProviderDefinition(typeDefinition, "Context"),
+          Throws.InvalidOperationException.With.Message.EqualTo("Cannot obtain storage provider for TypeDefinitions without storage entities. Context"));
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedCollectionRelationDataRegistrationAgentTest.cs b/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedCollectionRelationDataRegistrationAgentTest.cs
index 1c79a9df6e..4ef3d4f729 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedCollectionRelationDataRegistrationAgentTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedCollectionRelationDataRegistrationAgentTest.cs
@@ -295,8 +295,9 @@ public void GroupAndRegisterRelatedObjects_OriginatingObjectOfInvalidType ()
               .With.Message.EqualTo(
                   "Cannot register relation end-point "
                   + "'Remotion.Data.DomainObjects.UnitTests.TestDomain.Customer.Orders' for domain object "
-                  + "'OrderItem|2f4d42c7-7ffa-490d-bfcd-a9101bbf4e1a|System.Guid'. The end-point belongs to an object of class 'Customer' but the domain object "
-                  + "has class 'OrderItem'."));
+                  + "'OrderItem|2f4d42c7-7ffa-490d-bfcd-a9101bbf4e1a|System.Guid'. The end-point belongs to an object of type "
+                  + "'Remotion.Data.DomainObjects.UnitTests.TestDomain.Customer' but the domain object "
+                  + "has type 'Remotion.Data.DomainObjects.UnitTests.TestDomain.OrderItem'."));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedRealObjectRelationDataRegistrationAgentTest.cs b/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedRealObjectRelationDataRegistrationAgentTest.cs
index d636af841f..e3c0d25aea 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedRealObjectRelationDataRegistrationAgentTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedRealObjectRelationDataRegistrationAgentTest.cs
@@ -145,8 +145,9 @@ public void GroupAndRegisterRelatedObjects_InvalidOriginalObject ()
           Throws.InvalidOperationException
               .With.Message.EqualTo(
                   "Cannot register relation end-point 'Remotion.Data.DomainObjects.UnitTests.TestDomain.OrderTicket.Order' for domain object "
-                  + "'Order|5682f032-2f0b-494b-a31c-c97f02b89c36|System.Guid'. The end-point belongs to an object of class 'OrderTicket' but the domain object "
-                  + "has class 'Order'."));
+                  + "'Order|5682f032-2f0b-494b-a31c-c97f02b89c36|System.Guid'. The end-point belongs to an object of type "
+                  + "'Remotion.Data.DomainObjects.UnitTests.TestDomain.OrderTicket' but the domain object "
+                  + "has type 'Remotion.Data.DomainObjects.UnitTests.TestDomain.Order'."));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedVirtualObjectRelationDataRegistrationAgentTest.cs b/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedVirtualObjectRelationDataRegistrationAgentTest.cs
index 93c7c4179b..3907f5ef65 100644
--- a/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedVirtualObjectRelationDataRegistrationAgentTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/Queries/EagerFetching/FetchedVirtualObjectRelationDataRegistrationAgentTest.cs
@@ -314,8 +314,9 @@ public void GroupAndRegisterRelatedObjects_OriginatingObjectOfInvalidType ()
               .With.Message.EqualTo(
                   "Cannot register relation end-point "
                   + "'Remotion.Data.DomainObjects.UnitTests.TestDomain.Employee.Computer' for domain object "
-                  + "'Computer|c7c26bf5-871d-48c7-822a-e9b05aac4e5a|System.Guid'. The end-point belongs to an object of class 'Employee' but the domain object "
-                  + "has class 'Computer'."));
+                  + "'Computer|c7c26bf5-871d-48c7-822a-e9b05aac4e5a|System.Guid'. The end-point belongs to an object of type "
+                  + "'Remotion.Data.DomainObjects.UnitTests.TestDomain.Employee' but the domain object "
+                  + "has type 'Remotion.Data.DomainObjects.UnitTests.TestDomain.Computer'."));
     }
 
     [Test]
diff --git a/Remotion/Data/DomainObjects.UnitTests/ReflectionUtilityTest.cs b/Remotion/Data/DomainObjects.UnitTests/ReflectionUtilityTest.cs
index e8d47c3c9f..7b2f0900c9 100644
--- a/Remotion/Data/DomainObjects.UnitTests/ReflectionUtilityTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/ReflectionUtilityTest.cs
@@ -35,14 +35,14 @@ namespace Remotion.Data.DomainObjects.UnitTests
   [TestFixture]
   public class ReflectionUtilityTest : StandardMappingTest
   {
-    private ClassDefinition _classDefinitionWithMixedProperty;
+    private TypeDefinition _typeDefinitionWithMixedProperty;
 
     [SetUp]
     public override void SetUp ()
     {
       base.SetUp();
-      _classDefinitionWithMixedProperty =
-          ClassDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithMixedProperty), typeof(MixinAddingProperty));
+      _typeDefinitionWithMixedProperty =
+          TypeDefinitionObjectMother.CreateClassDefinitionWithMixins(typeof(ClassWithMixedProperty), typeof(MixinAddingProperty));
     }
 
     [Test]
@@ -246,7 +246,7 @@ public void GetDeclaringDomainObjectTypeForProperty_NoMixedProperty ()
     {
       var property = PropertyInfoAdapter.Create(typeof(ClassWithMixedProperty).GetProperty("PublicNonMixedProperty"));
 
-      var result = ReflectionUtility.GetDeclaringDomainObjectTypeForProperty(property, _classDefinitionWithMixedProperty);
+      var result = ReflectionUtility.GetDeclaringDomainObjectTypeForProperty(property, _typeDefinitionWithMixedProperty);
 
       Assert.That(result, Is.SameAs(typeof(ClassWithMixedProperty)));
     }
@@ -256,7 +256,7 @@ public void GetDeclaringDomainObjectTypeForProperty_MixedProperty ()
     {
       var property = PropertyInfoAdapter.Create(typeof(MixinAddingProperty).GetProperty("MixedProperty"));
 
-      var result = ReflectionUtility.GetDeclaringDomainObjectTypeForProperty(property, _classDefinitionWithMixedProperty);
+      var result = ReflectionUtility.GetDeclaringDomainObjectTypeForProperty(property, _typeDefinitionWithMixedProperty);
 
       Assert.That(result, Is.SameAs(typeof(ClassWithMixedProperty)));
     }
@@ -266,7 +266,7 @@ public void IsMixedProperty_NoMixedProperty_ReturnsFalse ()
     {
       var property = PropertyInfoAdapter.Create(typeof(ClassWithMixedProperty).GetProperty("PublicNonMixedProperty"));
 
-      var result = ReflectionUtility.IsMixedProperty(property, _classDefinitionWithMixedProperty);
+      var result = ReflectionUtility.IsMixedProperty(property, _typeDefinitionWithMixedProperty);
 
       Assert.That(result, Is.False);
     }
@@ -276,7 +276,7 @@ public void IsMixedProperty_MixedProperty_ReturnsTrue ()
     {
       var property = PropertyInfoAdapter.Create(typeof(MixinAddingProperty).GetProperty("MixedProperty"));
 
-      var result = ReflectionUtility.IsMixedProperty(property, _classDefinitionWithMixedProperty);
+      var result = ReflectionUtility.IsMixedProperty(property, _typeDefinitionWithMixedProperty);
 
       Assert.That(result, Is.True);
     }
diff --git a/Remotion/Data/DomainObjects.UnitTests/StandardMappingTest.cs b/Remotion/Data/DomainObjects.UnitTests/StandardMappingTest.cs
index 7557e24645..0e9dd47a43 100644
--- a/Remotion/Data/DomainObjects.UnitTests/StandardMappingTest.cs
+++ b/Remotion/Data/DomainObjects.UnitTests/StandardMappingTest.cs
@@ -119,9 +119,9 @@ protected PropertyDefinition GetPropertyDefinition (Type declaringType, string s
       return propertyDefinition;
     }
 
-    protected PropertyDefinition GetPropertyDefinition (Type classType, Type declaringType, string shortPropertyName)
+    protected PropertyDefinition GetPropertyDefinition (Type type, Type declaringType, string shortPropertyName)
     {
-      var propertyDefinition = GetTypeDefinition(classType)
+      var propertyDefinition = GetTypeDefinition(type)
           .PropertyAccessorDataCache
           .GetMandatoryPropertyAccessorData(declaringType, shortPropertyName)
           .PropertyDefinition;
@@ -134,19 +134,19 @@ protected IRelationEndPointDefinition GetSomeEndPointDefinition ()
       return GetEndPointDefinition(typeof(Order), "OrderItems");
     }
 
-    protected IRelationEndPointDefinition GetEndPointDefinition (Type classType, string shortPropertyName)
+    protected IRelationEndPointDefinition GetEndPointDefinition (Type type, string shortPropertyName)
     {
-      return GetEndPointDefinition(classType, classType, shortPropertyName);
+      return GetEndPointDefinition(type, type, shortPropertyName);
     }
 
-    protected IRelationEndPointDefinition GetEndPointDefinition (Type classType, Type propertyDeclaringType, string shortPropertyName)
+    protected IRelationEndPointDefinition GetEndPointDefinition (Type type, Type propertyDeclaringType, string shortPropertyName)
     {
-      var endPointDefinition = GetTypeDefinition(classType)
+      var endPointDefinition = GetTypeDefinition(type)
           .PropertyAccessorDataCache
           .GetMandatoryPropertyAccessorData(propertyDeclaringType, shortPropertyName)
           .RelationEndPointDefinition;
       Assertion.IsNotNull(
-          endPointDefinition, "Property '{0}.{1}' is not a relation end-point on '{2}'.", propertyDeclaringType, shortPropertyName, classType.Name);
+          endPointDefinition, "Property '{0}.{1}' is not a relation end-point on '{2}'.", propertyDeclaringType, shortPropertyName, type.Name);
       return endPointDefinition;
     }
 
@@ -190,9 +190,14 @@ protected string GetPropertyIdentifier (Type declaringType, string shortProperty
       return declaringType.FullName + "." + shortPropertyName;
     }
 
-    protected ClassDefinition GetTypeDefinition (Type classType)
+    protected ClassDefinition GetClassDefinition (Type classType)
     {
-      return Configuration.GetTypeDefinition(classType);
+      return Configuration.GetClassDefinition(classType);
+    }
+
+    protected TypeDefinition GetTypeDefinition (Type type)
+    {
+      return Configuration.GetTypeDefinition(type);
     }
 
   }
diff --git a/Remotion/Data/DomainObjects/ClientTransaction.cs b/Remotion/Data/DomainObjects/ClientTransaction.cs
index a593e671e5..1195bac86b 100644
--- a/Remotion/Data/DomainObjects/ClientTransaction.cs
+++ b/Remotion/Data/DomainObjects/ClientTransaction.cs
@@ -890,7 +890,7 @@ protected internal virtual DomainObject NewObject (Type domainObjectType, ParamL
     ArgumentUtility.CheckNotNull("domainObjectType", domainObjectType);
     ArgumentUtility.CheckNotNull("constructorParameters", constructorParameters);
 
-    var classDefinition = MappingConfiguration.Current.GetTypeDefinition(domainObjectType);
+    var classDefinition = MappingConfiguration.Current.GetClassDefinition(domainObjectType);
     return _objectLifetimeAgent.NewObject(classDefinition, constructorParameters);
   }
 
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/IMappingLoader.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/IMappingLoader.cs
index 6b43705b80..ccfd5c5573 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/IMappingLoader.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/IMappingLoader.cs
@@ -23,8 +23,8 @@ namespace Remotion.Data.DomainObjects.ConfigurationLoader
 {
   public interface IMappingLoader : IMappingValidatorFactory
   {
-    ClassDefinition[] GetClassDefinitions ();
-    RelationDefinition[] GetRelationDefinitions (IDictionary<Type, ClassDefinition> classDefinitions);
+    TypeDefinition[] GetTypeDefinitions ();
+    RelationDefinition[] GetRelationDefinitions (IDictionary<Type, TypeDefinition> typeDefinitions);
     bool ResolveTypes { get; }
     IMemberInformationNameResolver NameResolver { get; }
   }
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/IMappingValidatorFactory.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/IMappingValidatorFactory.cs
index 532a24b834..12e50d50df 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/IMappingValidatorFactory.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/IMappingValidatorFactory.cs
@@ -24,7 +24,7 @@ namespace Remotion.Data.DomainObjects.ConfigurationLoader
   /// </summary>
   public interface IMappingValidatorFactory
   {
-    IClassDefinitionValidator CreateClassDefinitionValidator ();
+    ITypeDefinitionValidator CreateTypeDefinitionValidator ();
     IPropertyDefinitionValidator CreatePropertyDefinitionValidator ();
     IRelationDefinitionValidator CreateRelationDefinitionValidator ();
     ISortExpressionValidator CreateSortExpressionValidator ();
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/ClassReflector.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/ClassReflector.cs
index de10f1318c..4b8e501e7f 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/ClassReflector.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/ClassReflector.cs
@@ -94,6 +94,7 @@ public ClassDefinition GetMetadata (ClassDefinition? baseClassDefinition)
               Type,
               IsAbstract(),
               baseClassDefinition,
+              Enumerable.Empty<InterfaceDefinition>(), // TODO R2I Mapping: Support interfaces
               storageGroupType,
               defaultStorageClass,
               persistentMixinFinder,
@@ -123,7 +124,7 @@ private bool IsAbstract ()
     private IEnumerable<IPropertyInformation> GetPropertyInfos (ClassDefinition classDefinition)
     {
       PropertyFinder propertyFinder = new PropertyFinder(
-          classDefinition.ClassType,
+          classDefinition.Type,
           classDefinition,
           classDefinition.BaseClass == null,
           true,
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/ISortExpressionDefinitionProvider.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/ISortExpressionDefinitionProvider.cs
index 9cfe92e217..191b80da8d 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/ISortExpressionDefinitionProvider.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/ISortExpressionDefinitionProvider.cs
@@ -32,7 +32,7 @@ public interface ISortExpressionDefinitionProvider
     [CanBeNull]
     SortExpressionDefinition? GetSortExpression (
         [NotNull] IPropertyInformation propertyInfo,
-        [NotNull] ClassDefinition referencedClassDefinition,
+        [NotNull] TypeDefinition referencedTypeDefinition,
         [CanBeNull] string? sortExpressionText);
   }
 }
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/MappingReflector.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/MappingReflector.cs
index 832a671842..e528b060a9 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/MappingReflector.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/MappingReflector.cs
@@ -134,28 +134,28 @@ public ITypeDiscoveryService TypeDiscoveryService
       get { return _typeDiscoveryService; }
     }
 
-    public ClassDefinition[] GetClassDefinitions ()
+    public TypeDefinition[] GetTypeDefinitions ()
     {
-      s_log.Info("Reflecting class definitions...");
+      s_log.Info("Reflecting type definitions...");
 
-      using (StopwatchScope.CreateScope(s_log, LogLevel.Info, "Time needed to reflect class definitions: {elapsed}."))
+      using (StopwatchScope.CreateScope(s_log, LogLevel.Info, "Time needed to reflect type definitions: {elapsed}."))
       {
         var types = GetDomainObjectTypesSorted();
-        var classDefinitions = MappingObjectFactory.CreateClassDefinitionCollection(types);
+        var typeDefinitions = MappingObjectFactory.CreateTypeDefinitionCollection(types);
 
-        return classDefinitions
-            .LogAndReturnValue(s_log, LogLevel.Info, result => string.Format("Generated {0} class definitions.", result.Length));
+        return typeDefinitions
+            .LogAndReturnValue(s_log, LogLevel.Info, result => string.Format("Generated {0} type definitions.", result.Length));
       }
     }
 
-    public RelationDefinition[] GetRelationDefinitions (IDictionary<Type, ClassDefinition> classDefinitions)
+    public RelationDefinition[] GetRelationDefinitions (IDictionary<Type, TypeDefinition> typeDefinitions)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
-      s_log.InfoFormat("Reflecting relation definitions of {0} class definitions...", classDefinitions.Count);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
+      s_log.InfoFormat("Reflecting relation definitions of {0} type definitions...", typeDefinitions.Count);
 
       using (StopwatchScope.CreateScope(s_log, LogLevel.Info, "Time needed to reflect relation definitions: {elapsed}."))
       {
-        var relationDefinitions = MappingObjectFactory.CreateRelationDefinitionCollection(classDefinitions);
+        var relationDefinitions = MappingObjectFactory.CreateRelationDefinitionCollection(typeDefinitions);
         return relationDefinitions
             .LogAndReturnValue(s_log, LogLevel.Info, result => string.Format("Generated {0} relation definitions.", result.Length));
       }
@@ -188,9 +188,9 @@ public IMappingObjectFactory MappingObjectFactory
       get { return _mappingObjectFactory; }
     }
 
-    public IClassDefinitionValidator CreateClassDefinitionValidator ()
+    public ITypeDefinitionValidator CreateTypeDefinitionValidator ()
     {
-      return new ClassDefinitionValidator(
+      return new TypeDefinitionValidator(
           new DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRule(),
           new DomainObjectTypeIsNotGenericValidationRule(),
           new InheritanceHierarchyFollowsClassHierarchyValidationRule(),
@@ -223,7 +223,7 @@ public IRelationDefinitionValidator CreateRelationDefinitionValidator ()
           new RelationEndPointNamesAreConsistentValidationRule(),
           new RelationEndPointTypesAreConsistentValidationRule(),
           new CheckForInvalidRelationEndPointsValidationRule(),
-          new CheckForTypeNotFoundClassDefinitionValidationRule());
+          new CheckForTypeNotFoundTypeDefinitionValidationRule());
     }
 
     public ISortExpressionValidator CreateSortExpressionValidator ()
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/MemberReflectorBase.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/MemberReflectorBase.cs
index 1f13b6cdac..798d93b454 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/MemberReflectorBase.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/MemberReflectorBase.cs
@@ -24,31 +24,31 @@ namespace Remotion.Data.DomainObjects.ConfigurationLoader.ReflectionBasedConfigu
   /// <summary>Base class for reflecting on the properties and relations of a class.</summary>
   public abstract class MemberReflectorBase
   {
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
     private readonly IPropertyInformation _propertyInfo;
     private readonly IMemberInformationNameResolver _nameResolver;
     private readonly IPropertyMetadataProvider _propertyMetadataProvider;
 
     protected MemberReflectorBase (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         IPropertyInformation propertyInfo,
         IMemberInformationNameResolver nameResolver,
         IPropertyMetadataProvider propertyMetadataProvider)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNull("propertyInfo", propertyInfo);
       ArgumentUtility.CheckNotNull("nameResolver", nameResolver);
       ArgumentUtility.CheckNotNull("propertyMetadataProvider", propertyMetadataProvider);
 
-      _classDefinition = classDefinition;
+      _typeDefinition = typeDefinition;
       _propertyInfo = propertyInfo;
       _nameResolver = nameResolver;
       _propertyMetadataProvider = propertyMetadataProvider;
     }
 
-    public ClassDefinition ClassDefinition
+    public TypeDefinition TypeDefinition
     {
-      get { return _classDefinition; }
+      get { return _typeDefinition; }
     }
 
     public IPropertyInformation PropertyInfo
@@ -73,14 +73,14 @@ public StorageClass GetStorageClass ()
 
     private StorageClass GetDefaultStorageClass ()
     {
-      switch (_classDefinition.DefaultStorageClass)
+      switch (_typeDefinition.DefaultStorageClass)
       {
         case DefaultStorageClass.Persistent:
           return StorageClass.Persistent;
         case DefaultStorageClass.Transaction:
           return StorageClass.Transaction;
         default:
-          throw new NotImplementedException($"{nameof(DefaultStorageClass)} '{_classDefinition.DefaultStorageClass}' is not supported.");
+          throw new NotImplementedException($"{nameof(DefaultStorageClass)} '{_typeDefinition.DefaultStorageClass}' is not supported.");
       }
     }
 
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/PropertyFinder.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/PropertyFinder.cs
index bc10b28e03..02ff604cef 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/PropertyFinder.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/PropertyFinder.cs
@@ -27,13 +27,13 @@ namespace Remotion.Data.DomainObjects.ConfigurationLoader.ReflectionBasedConfigu
   /// </summary>
   public class PropertyFinder : PropertyFinderBase
   {
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
     private readonly IDomainModelConstraintProvider _domainModelConstraintProvider;
     private readonly ISortExpressionDefinitionProvider _sortExpressionDefinitionProvider;
 
     public PropertyFinder (
         Type type,
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         bool includeBaseProperties,
         bool includeMixinProperties,
         IMemberInformationNameResolver nameResolver,
@@ -43,11 +43,11 @@ public PropertyFinder (
         ISortExpressionDefinitionProvider sortExpressionDefinitionProvider)
         : base(type, includeBaseProperties, includeMixinProperties, nameResolver, persistentMixinFinder, propertyMetadataProvider)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNull("domainModelConstraintProvider", domainModelConstraintProvider);
       ArgumentUtility.CheckNotNull("sortExpressionDefinitionProvider", sortExpressionDefinitionProvider);
 
-      _classDefinition = classDefinition;
+      _typeDefinition = typeDefinition;
       _domainModelConstraintProvider = domainModelConstraintProvider;
       _sortExpressionDefinitionProvider = sortExpressionDefinitionProvider;
     }
@@ -75,7 +75,7 @@ protected override PropertyFinderBase CreateNewFinder (
     {
       return new PropertyFinder(
           type,
-          _classDefinition,
+          _typeDefinition,
           includeBaseProperties,
           includeMixinProperties,
           nameResolver,
@@ -90,7 +90,7 @@ private bool IsVirtualRelationEndPoint (IPropertyInformation propertyInfo)
       if (!ReflectionUtility.IsRelationType(propertyInfo.PropertyType))
         return false;
       var relationEndPointReflector = RelationEndPointReflector.CreateRelationEndPointReflector(
-          _classDefinition,
+          _typeDefinition,
           propertyInfo,
           NameResolver,
           PropertyMetadataProvider,
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/PropertyReflector.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/PropertyReflector.cs
index 56b2669269..7f60ab3860 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/PropertyReflector.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/PropertyReflector.cs
@@ -31,13 +31,13 @@ public class PropertyReflector : MemberReflectorBase
     private readonly IPropertyDefaultValueProvider _propertyDefaultValueProvider;
 
     public PropertyReflector (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         IPropertyInformation propertyInfo,
         IMemberInformationNameResolver nameResolver,
         IPropertyMetadataProvider propertyMetadataProvider,
         IDomainModelConstraintProvider domainModelConstraintProvider,
         IPropertyDefaultValueProvider propertyDefaultValueProvider)
-        : base(classDefinition, propertyInfo, nameResolver, propertyMetadataProvider)
+        : base(typeDefinition, propertyInfo, nameResolver, propertyMetadataProvider)
     {
       ArgumentUtility.CheckNotNull("domainModelConstraintProvider", domainModelConstraintProvider);
       ArgumentUtility.CheckNotNull("propertyDefaultValueProvider", propertyDefaultValueProvider);
@@ -51,7 +51,7 @@ public PropertyDefinition GetMetadata ()
       var isNullable = IsNullable();
 
       var propertyDefinition = new PropertyDefinition(
-          ClassDefinition,
+          TypeDefinition,
           PropertyInfo,
           GetPropertyName(),
           IsDomainObject(),
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RdbmsRelationEndPointReflector.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RdbmsRelationEndPointReflector.cs
index 0e09480ce6..44e4573c25 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RdbmsRelationEndPointReflector.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RdbmsRelationEndPointReflector.cs
@@ -27,13 +27,13 @@ namespace Remotion.Data.DomainObjects.ConfigurationLoader.ReflectionBasedConfigu
   public class RdbmsRelationEndPointReflector : RelationEndPointReflector<DBBidirectionalRelationAttribute>
   {
     public RdbmsRelationEndPointReflector (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         IPropertyInformation propertyInfo,
         IMemberInformationNameResolver nameResolver,
         IPropertyMetadataProvider propertyMetadataProvider,
         IDomainModelConstraintProvider domainModelConstraintProvider,
         ISortExpressionDefinitionProvider sortExpressionDefinitionProvider)
-        : base(classDefinition, propertyInfo, nameResolver, propertyMetadataProvider, domainModelConstraintProvider, sortExpressionDefinitionProvider)
+        : base(typeDefinition, propertyInfo, nameResolver, propertyMetadataProvider, domainModelConstraintProvider, sortExpressionDefinitionProvider)
     {
     }
 
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationEndPointReflector.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationEndPointReflector.cs
index d18db0db3a..7fd3c00e48 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationEndPointReflector.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationEndPointReflector.cs
@@ -27,7 +27,7 @@ namespace Remotion.Data.DomainObjects.ConfigurationLoader.ReflectionBasedConfigu
   public static class RelationEndPointReflector
   {
     public static RdbmsRelationEndPointReflector CreateRelationEndPointReflector (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         IPropertyInformation propertyInfo,
         IMemberInformationNameResolver nameResolver,
         IPropertyMetadataProvider propertyMetadataProvider,
@@ -35,7 +35,7 @@ public static RdbmsRelationEndPointReflector CreateRelationEndPointReflector (
         ISortExpressionDefinitionProvider sortExpressionDefinitionProvider)
     {
       return new RdbmsRelationEndPointReflector(
-          classDefinition,
+          typeDefinition,
           propertyInfo,
           nameResolver,
           propertyMetadataProvider,
@@ -57,13 +57,13 @@ private class DeferredRelationEndPointDefinition
     private readonly ISortExpressionDefinitionProvider _sortExpressionDefinitionProvider;
 
     protected RelationEndPointReflector (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         IPropertyInformation propertyInfo,
         IMemberInformationNameResolver nameResolver,
         IPropertyMetadataProvider propertyMetadataProvider,
         IDomainModelConstraintProvider domainModelConstraintProvider,
         ISortExpressionDefinitionProvider sortExpressionDefinitionProvider)
-        : base(classDefinition, propertyInfo, nameResolver, propertyMetadataProvider)
+        : base(typeDefinition, propertyInfo, nameResolver, propertyMetadataProvider)
     {
       ArgumentUtility.CheckNotNull("domainModelConstraintProvider", domainModelConstraintProvider);
       ArgumentUtility.CheckNotNull("sortExpressionDefinitionProvider", sortExpressionDefinitionProvider);
@@ -77,28 +77,28 @@ protected RelationEndPointReflector (
     public IRelationEndPointDefinition GetMetadata ()
     {
       if (IsVirtualEndRelationEndpoint())
-        return CreateVirtualRelationEndPointDefinition(ClassDefinition);
+        return CreateVirtualRelationEndPointDefinition(TypeDefinition);
       else
-        return CreateRelationEndPointDefinition(ClassDefinition);
+        return CreateRelationEndPointDefinition(TypeDefinition);
     }
 
-    private IRelationEndPointDefinition CreateRelationEndPointDefinition (ClassDefinition classDefinition)
+    private IRelationEndPointDefinition CreateRelationEndPointDefinition (TypeDefinition typeDefinition)
     {
       var propertyName = GetPropertyName();
 
-      PropertyDefinition propertyDefinition = classDefinition.GetMandatoryPropertyDefinition(propertyName);
+      PropertyDefinition propertyDefinition = typeDefinition.GetMandatoryPropertyDefinition(propertyName);
       if (!propertyDefinition.IsObjectID)
-        return new TypeNotObjectIDRelationEndPointDefinition(classDefinition, propertyName, propertyDefinition.PropertyInfo.PropertyType);
+        return new TypeNotObjectIDRelationEndPointDefinition(typeDefinition, propertyName, propertyDefinition.PropertyInfo.PropertyType);
       else
         return new RelationEndPointDefinition(propertyDefinition, IsMandatory());
     }
 
-    private IRelationEndPointDefinition CreateVirtualRelationEndPointDefinition (ClassDefinition classDefinition)
+    private IRelationEndPointDefinition CreateVirtualRelationEndPointDefinition (TypeDefinition typeDefinition)
     {
       if (ReflectionUtility.IsDomainObject(PropertyInfo.PropertyType))
       {
         var relationEndPointDefinition = new VirtualObjectRelationEndPointDefinition(
-            classDefinition,
+            typeDefinition,
             GetPropertyName(),
             IsMandatory(),
             PropertyInfo);
@@ -113,7 +113,7 @@ private IRelationEndPointDefinition CreateVirtualRelationEndPointDefinition (Cla
       {
         var deferredRelationEndPointDefinition = new DeferredRelationEndPointDefinition();
         var relationEndPointDefinition = new DomainObjectCollectionRelationEndPointDefinition(
-            classDefinition,
+            typeDefinition,
             GetPropertyName(),
             IsMandatory(),
             GetSortExpressionDefinition(deferredRelationEndPointDefinition),
@@ -126,7 +126,7 @@ private IRelationEndPointDefinition CreateVirtualRelationEndPointDefinition (Cla
       {
         var deferredRelationEndPointDefinition = new DeferredRelationEndPointDefinition();
         var relationEndPointDefinition = new VirtualCollectionRelationEndPointDefinition(
-            classDefinition,
+            typeDefinition,
             GetPropertyName(),
             IsMandatory(),
             GetSortExpressionDefinition(deferredRelationEndPointDefinition),
@@ -137,7 +137,7 @@ private IRelationEndPointDefinition CreateVirtualRelationEndPointDefinition (Cla
       }
       else
       {
-        return new TypeNotCompatibleWithVirtualRelationEndPointDefinition(classDefinition, GetPropertyName(), PropertyInfo.PropertyType);
+        return new TypeNotCompatibleWithVirtualRelationEndPointDefinition(typeDefinition, GetPropertyName(), PropertyInfo.PropertyType);
       }
     }
 
@@ -159,8 +159,8 @@ private bool IsMandatory ()
           {
             var relationEndPointDefinition = deferredRelationEndPointDefinition.Value;
             Assertion.IsNotNull(relationEndPointDefinition, "RelationEndPointDefinition was not initialized.");
-            var oppositeClassDefinition = relationEndPointDefinition.GetOppositeEndPointDefinition().ClassDefinition;
-            return sortExpressionDefinitionProvider.GetSortExpression(propertyInfo, oppositeClassDefinition, sortExpressionText);
+            var oppositeTypeDefinition = relationEndPointDefinition.GetOppositeEndPointDefinition().TypeDefinition;
+            return sortExpressionDefinitionProvider.GetSortExpression(propertyInfo, oppositeTypeDefinition, sortExpressionText);
           }, LazyThreadSafetyMode.ExecutionAndPublication);
     }
   }
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationReflector.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationReflector.cs
index c44b6d5c60..d059bafbb9 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationReflector.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationReflector.cs
@@ -27,20 +27,20 @@ namespace Remotion.Data.DomainObjects.ConfigurationLoader.ReflectionBasedConfigu
   public class RelationReflector : RelationReflectorBase<BidirectionalRelationAttribute>
   {
     public RelationReflector (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         IPropertyInformation propertyInfo,
         IMemberInformationNameResolver nameResolver,
         IPropertyMetadataProvider propertyMetadataProvider)
-        : base(classDefinition, propertyInfo, nameResolver, propertyMetadataProvider)
+        : base(typeDefinition, propertyInfo, nameResolver, propertyMetadataProvider)
     {
     }
 
-    public RelationDefinition GetMetadata (IDictionary<Type, ClassDefinition> classDefinitions)
+    public RelationDefinition GetMetadata (IDictionary<Type, TypeDefinition> typeDefinitions)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
-      var firstEndPoint = GetEndPointDefinition(ClassDefinition, PropertyInfo);
-      var secondEndPoint = GetOppositeEndPointDefinition(classDefinitions);
+      var firstEndPoint = GetEndPointDefinition(TypeDefinition, PropertyInfo);
+      var secondEndPoint = GetOppositeEndPointDefinition(typeDefinitions);
 
       var relationID = GetRelationID(firstEndPoint, secondEndPoint);
       return new RelationDefinition(relationID, firstEndPoint, secondEndPoint);
@@ -56,65 +56,65 @@ private string GetRelationID (IRelationEndPointDefinition first, IRelationEndPoi
 
       if (endPoints.Right.IsAnonymous)
       {
-        return string.Format("{0}:{1}", endPoints.Left.ClassDefinition.ClassType.GetFullNameChecked(), leftPropertyName);
+        return string.Format("{0}:{1}", endPoints.Left.TypeDefinition.Type.GetFullNameChecked(), leftPropertyName);
       }
       else
       {
         var rightPropertyName = NameResolver.GetPropertyName(endPoints.Right.PropertyInfo);
-        return string.Format("{0}:{1}->{2}", endPoints.Left.ClassDefinition.ClassType.GetFullNameChecked(), leftPropertyName, rightPropertyName);
+        return string.Format("{0}:{1}->{2}", endPoints.Left.TypeDefinition.Type.GetFullNameChecked(), leftPropertyName, rightPropertyName);
       }
     }
 
-    private IRelationEndPointDefinition GetOppositeEndPointDefinition (IDictionary<Type, ClassDefinition> classDefinitions)
+    private IRelationEndPointDefinition GetOppositeEndPointDefinition (IDictionary<Type, TypeDefinition> typeDefinitions)
     {
       if (!IsBidirectionalRelation)
-        return CreateOppositeAnonymousRelationEndPointDefinition(classDefinitions);
+        return CreateOppositeAnonymousRelationEndPointDefinition(typeDefinitions);
       Assertion.DebugIsNotNull(BidirectionalRelationAttribute, "BidirectionalRelationAttribute != null");
 
-      var oppositeClassDefinition = GetOppositeClassDefinition(classDefinitions);
+      var oppositeTypeDefinition = GetOppositeTypeDefinition(typeDefinitions);
       var oppositePropertyInfo = GetOppositePropertyInfo();
       if (oppositePropertyInfo == null)
-        return new PropertyNotFoundRelationEndPointDefinition(oppositeClassDefinition, BidirectionalRelationAttribute.OppositeProperty, typeof(void));
+        return new PropertyNotFoundRelationEndPointDefinition(oppositeTypeDefinition, BidirectionalRelationAttribute.OppositeProperty, typeof(void));
       else
-        return GetEndPointDefinition(oppositeClassDefinition, oppositePropertyInfo);
+        return GetEndPointDefinition(oppositeTypeDefinition, oppositePropertyInfo);
     }
 
-    private AnonymousRelationEndPointDefinition CreateOppositeAnonymousRelationEndPointDefinition (IDictionary<Type, ClassDefinition> classDefinitions)
+    private AnonymousRelationEndPointDefinition CreateOppositeAnonymousRelationEndPointDefinition (IDictionary<Type, TypeDefinition> typeDefinitions)
     {
-      var oppositeClassDefinition = GetOppositeClassDefinition(classDefinitions);
-      return new AnonymousRelationEndPointDefinition(oppositeClassDefinition);
+      var oppositeTypeDefinition = GetOppositeTypeDefinition(typeDefinitions);
+      return new AnonymousRelationEndPointDefinition(oppositeTypeDefinition);
     }
 
-    private IRelationEndPointDefinition GetEndPointDefinition (ClassDefinition classDefinition, IPropertyInformation propertyInfo)
+    private IRelationEndPointDefinition GetEndPointDefinition (TypeDefinition typeDefinition, IPropertyInformation propertyInfo)
     {
-      var endPointDefinition = classDefinition.GetRelationEndPointDefinition(NameResolver.GetPropertyName(propertyInfo));
+      var endPointDefinition = typeDefinition.GetRelationEndPointDefinition(NameResolver.GetPropertyName(propertyInfo));
       if (endPointDefinition != null)
         return endPointDefinition;
 
-      return new PropertyNotFoundRelationEndPointDefinition(classDefinition, propertyInfo.Name, propertyInfo.PropertyType);
+      return new PropertyNotFoundRelationEndPointDefinition(typeDefinition, propertyInfo.Name, propertyInfo.PropertyType);
     }
 
-    private ClassDefinition GetOppositeClassDefinition (IDictionary<Type, ClassDefinition> classDefinitions)
+    private TypeDefinition GetOppositeTypeDefinition (IDictionary<Type, TypeDefinition> typeDefinitions)
     {
       var type = ReflectionUtility.GetRelatedObjectTypeFromRelationProperty(PropertyInfo);
       if (type == null)
       {
-        var notFoundClassDefinition = new ClassDefinitionForUnresolvedRelationPropertyType(PropertyInfo.PropertyType.Name, typeof(DomainObject), PropertyInfo);
-        notFoundClassDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
-        notFoundClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
-        return notFoundClassDefinition;
+        var notFoundTypeDefinition = new TypeDefinitionForUnresolvedRelationPropertyType(typeof(DomainObject), PropertyInfo);
+        notFoundTypeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
+        notFoundTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+        return notFoundTypeDefinition;
       }
 
-      var oppositeClassDefinition = classDefinitions.GetValueOrDefault(type);
-      if (oppositeClassDefinition == null)
+      var oppositeTypeDefinition = typeDefinitions.GetValueOrDefault(type);
+      if (oppositeTypeDefinition == null)
       {
-        var notFoundClassDefinition = new ClassDefinitionForUnresolvedRelationPropertyType(type.Name, type, PropertyInfo);
-        notFoundClassDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
-        notFoundClassDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
-        return notFoundClassDefinition;
+        var notFoundTypeDefinition = new TypeDefinitionForUnresolvedRelationPropertyType(type, PropertyInfo);
+        notFoundTypeDefinition.SetPropertyDefinitions(new PropertyDefinitionCollection());
+        notFoundTypeDefinition.SetRelationEndPointDefinitions(new RelationEndPointDefinitionCollection());
+        return notFoundTypeDefinition;
       }
 
-      return oppositeClassDefinition;
+      return oppositeTypeDefinition;
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationReflectorBase.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationReflectorBase.cs
index 419ee3fb1c..efd857f4a0 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationReflectorBase.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/RelationReflectorBase.cs
@@ -27,11 +27,11 @@ namespace Remotion.Data.DomainObjects.ConfigurationLoader.ReflectionBasedConfigu
   public abstract class RelationReflectorBase<T> : MemberReflectorBase where T: BidirectionalRelationAttribute
   {
     protected RelationReflectorBase (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         IPropertyInformation propertyInfo,
         IMemberInformationNameResolver nameResolver,
         IPropertyMetadataProvider propertyMetadataProvider)
-        : base(classDefinition, propertyInfo, nameResolver, propertyMetadataProvider)
+        : base(typeDefinition, propertyInfo, nameResolver, propertyMetadataProvider)
     {
       BidirectionalRelationAttribute = PropertyInfo.GetCustomAttribute<T>(true);
     }
diff --git a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/SortExpressionDefinitionProvider.cs b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/SortExpressionDefinitionProvider.cs
index 5bc621e60f..287234e3f9 100644
--- a/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/SortExpressionDefinitionProvider.cs
+++ b/Remotion/Data/DomainObjects/ConfigurationLoader/ReflectionBasedConfigurationLoader/SortExpressionDefinitionProvider.cs
@@ -37,18 +37,18 @@ public SortExpressionDefinitionProvider ()
 
     public SortExpressionDefinition? GetSortExpression (
         IPropertyInformation propertyInfo,
-        ClassDefinition referencedClassDefinition,
+        TypeDefinition referencedTypeDefinition,
         string? sortExpressionText)
     {
       ArgumentUtility.CheckNotNull("propertyInfo", propertyInfo);
-      ArgumentUtility.CheckNotNull("referencedClassDefinition", referencedClassDefinition);
+      ArgumentUtility.CheckNotNull("referencedTypeDefinition", referencedTypeDefinition);
 
       if (sortExpressionText == null)
         return null;
 
       try
       {
-        var parser = new SortExpressionParser(referencedClassDefinition);
+        var parser = new SortExpressionParser(referencedTypeDefinition);
         return parser.Parse(sortExpressionText);
       }
       catch (MappingException ex)
diff --git a/Remotion/Data/DomainObjects/DataManagement/CollectionData/DomainObjectCollectionDataExtensions.cs b/Remotion/Data/DomainObjects/DataManagement/CollectionData/DomainObjectCollectionDataExtensions.cs
index 1286937c11..c170546fa4 100644
--- a/Remotion/Data/DomainObjects/DataManagement/CollectionData/DomainObjectCollectionDataExtensions.cs
+++ b/Remotion/Data/DomainObjects/DataManagement/CollectionData/DomainObjectCollectionDataExtensions.cs
@@ -53,7 +53,7 @@ public static void AddRangeAndCheckItems (this IDomainObjectCollectionData data,
         if (domainObject == null)
           throw ArgumentUtility.CreateArgumentItemNullException("domainObjects", index);
         if (requiredItemType != null && !requiredItemType.IsInstanceOfType(domainObject))
-          throw ArgumentUtility.CreateArgumentItemTypeException("domainObjects", index, requiredItemType, domainObject.ID.ClassDefinition.ClassType);
+          throw ArgumentUtility.CreateArgumentItemTypeException("domainObjects", index, requiredItemType, domainObject.ID.ClassDefinition.Type);
         if (data.ContainsObjectID(domainObject.ID))
         {
           throw new ArgumentException(
diff --git a/Remotion/Data/DomainObjects/DataManagement/CollectionData/IncompleteEndPointModicationVirtualCollectionData.cs b/Remotion/Data/DomainObjects/DataManagement/CollectionData/IncompleteEndPointModicationVirtualCollectionData.cs
index 92b7a3d500..d71b771f3e 100644
--- a/Remotion/Data/DomainObjects/DataManagement/CollectionData/IncompleteEndPointModicationVirtualCollectionData.cs
+++ b/Remotion/Data/DomainObjects/DataManagement/CollectionData/IncompleteEndPointModicationVirtualCollectionData.cs
@@ -51,7 +51,7 @@ IEnumerator IEnumerable.GetEnumerator ()
 
     public int Count => 0;
 
-    public Type RequiredItemType => _associatedEndPointID.Definition.GetOppositeEndPointDefinition().ClassDefinition.ClassType;
+    public Type RequiredItemType => _associatedEndPointID.Definition.GetOppositeEndPointDefinition().TypeDefinition.Type;
 
     public bool IsReadOnly => false;
 
diff --git a/Remotion/Data/DomainObjects/DataManagement/CollectionData/VirtualCollectionData.cs b/Remotion/Data/DomainObjects/DataManagement/CollectionData/VirtualCollectionData.cs
index 146047100e..1975006c1d 100644
--- a/Remotion/Data/DomainObjects/DataManagement/CollectionData/VirtualCollectionData.cs
+++ b/Remotion/Data/DomainObjects/DataManagement/CollectionData/VirtualCollectionData.cs
@@ -82,7 +82,7 @@ public void ResetCachedDomainObjects ()
 
     public int Count => GetCachedDomainObjects().Count;
 
-    public Type RequiredItemType  => _associatedEndPointID.Definition.GetOppositeEndPointDefinition().ClassDefinition.ClassType;
+    public Type RequiredItemType  => _associatedEndPointID.Definition.GetOppositeEndPointDefinition().TypeDefinition.Type;
 
     public bool IsReadOnly { get; } = false;
 
@@ -182,8 +182,8 @@ private IReadOnlyDictionary<ObjectID, DomainObject> GetCachedDomainObjects ()
       {
         var foreignKeyRelationEndPointDefinition = (RelationEndPointDefinition)_associatedEndPointID.Definition.GetOppositeEndPointDefinition();
         var foreignKeyPropertyDefinition = foreignKeyRelationEndPointDefinition.PropertyDefinition;
-        var requiredClassDefinition = foreignKeyRelationEndPointDefinition.ClassDefinition;
-        var requiredItemType = requiredClassDefinition.ClassType;
+        var requiredTypeDefinition = foreignKeyRelationEndPointDefinition.TypeDefinition;
+        var requiredItemType = requiredTypeDefinition.Type;
         var foreignKeyValue = _associatedEndPointID.ObjectID;
 
         _cachedDomainObjects = _dataContainerMap
@@ -192,7 +192,7 @@ private IReadOnlyDictionary<ObjectID, DomainObject> GetCachedDomainObjects ()
             .Where(dc => requiredItemType.IsAssignableFrom(dc.DomainObjectType))
 #if DEBUG
             // Only in debug builds for performance reasons. The .NET type comparison is sufficient for filtering the types until interface support is added.
-            .Where(dc => requiredClassDefinition.IsSameOrBaseClassOf(dc.ClassDefinition))
+            .Where(dc => requiredTypeDefinition.IsAssignableFrom(dc.ClassDefinition))
 #endif
             .Where(dc => (ObjectID?)dc.GetValueWithoutEvents(foreignKeyPropertyDefinition, _valueAccess) == foreignKeyValue)
             .ToDictionary(dc => dc.ID, dc => dc.DomainObject);
diff --git a/Remotion/Data/DomainObjects/DataManagement/DataContainer.cs b/Remotion/Data/DomainObjects/DataManagement/DataContainer.cs
index 3a672dc74e..b6b6534569 100644
--- a/Remotion/Data/DomainObjects/DataManagement/DataContainer.cs
+++ b/Remotion/Data/DomainObjects/DataManagement/DataContainer.cs
@@ -455,7 +455,7 @@ public Type DomainObjectType
       get
       {
         CheckNotDiscarded();
-        return _id.ClassDefinition.ClassType;
+        return _id.ClassDefinition.Type;
       }
     }
 
diff --git a/Remotion/Data/DomainObjects/DataManagement/PropertyValue.cs b/Remotion/Data/DomainObjects/DataManagement/PropertyValue.cs
index ed55c2fac7..2fe1997735 100644
--- a/Remotion/Data/DomainObjects/DataManagement/PropertyValue.cs
+++ b/Remotion/Data/DomainObjects/DataManagement/PropertyValue.cs
@@ -78,9 +78,9 @@ public PropertyValue (PropertyDefinition definition, object? value)
 
       if (!IsTypeSupported(definition.PropertyType))
       {
-        var message = string.Format("The property '{0}' (declared on class '{1}') is invalid because its values cannot be copied. Only value types, "
+        var message = string.Format("The property '{0}' (declared on type '{1}') is invalid because its values cannot be copied. Only value types, "
             + "strings, the Type type, byte arrays, types implementing IStructuralEquatable, and ObjectIDs are currently supported, but the property's type is '{2}'.",
-            definition.PropertyName, definition.ClassDefinition.ID, definition.PropertyType.GetFullNameSafe());
+            definition.PropertyName, definition.TypeDefinition.Type.GetFullNameSafe(), definition.PropertyType.GetFullNameSafe());
         throw new NotSupportedException(message);
       }
 
diff --git a/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/RelationEndPointID.cs b/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/RelationEndPointID.cs
index b90bd21bc9..8fd409ab5e 100644
--- a/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/RelationEndPointID.cs
+++ b/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/RelationEndPointID.cs
@@ -214,11 +214,11 @@ private RelationEndPointID (SerializationInfo info, StreamingContext context)
       ArgumentUtility.CheckNotNull("info", info);
 
       var objectID = (ObjectID?)info.GetValue("ObjectID", typeof(ObjectID));
-      var classDefinitionID = info.GetString("ClassID")!;
+      var type = (Type)info.GetValue("Type", typeof(Type))!;
       var propertyName = info.GetString("PropertyName")!;
 
-      var classDefinition = MappingConfiguration.Current.GetClassDefinition(classDefinitionID);
-      var relationEndPointDefinition = classDefinition.GetMandatoryRelationEndPointDefinition(propertyName);
+      var typeDefinition = MappingConfiguration.Current.GetTypeDefinition(type);
+      var relationEndPointDefinition = typeDefinition.GetMandatoryRelationEndPointDefinition(propertyName);
 
       _objectID = objectID;
       _definition = relationEndPointDefinition;
@@ -232,19 +232,19 @@ void ISerializable.GetObjectData (SerializationInfo info, StreamingContext conte
       ArgumentUtility.CheckNotNull("info", info);
 
       info.AddValue("ObjectID", _objectID);
-      info.AddValue("ClassID", _definition.ClassDefinition.ID);
+      info.AddValue("Type", _definition.TypeDefinition.Type);
       info.AddValue("PropertyName", _definition.PropertyName);
     }
 
     // ReSharper disable UnusedMember.Local
     private RelationEndPointID (FlattenedDeserializationInfo info)
     {
-      var classDefinitionID = info.GetValueForHandle<string>();
+      var type = info.GetValue<Type>();
       var propertyName = info.GetValueForHandle<string>();
       var objectID = info.GetNullableValueForHandle<ObjectID>();
 
-      var classDefinition = MappingConfiguration.Current.GetClassDefinition(classDefinitionID);
-      var relationEndPointDefinition = classDefinition.GetMandatoryRelationEndPointDefinition(propertyName);
+      var typeDefinition = MappingConfiguration.Current.GetTypeDefinition(type);
+      var relationEndPointDefinition = typeDefinition.GetMandatoryRelationEndPointDefinition(propertyName);
 
       _objectID = objectID;
       _definition = relationEndPointDefinition;
@@ -253,7 +253,7 @@ private RelationEndPointID (FlattenedDeserializationInfo info)
 
     void IFlattenedSerializable.SerializeIntoFlatStructure (FlattenedSerializationInfo info)
     {
-      info.AddHandle(_definition.ClassDefinition.ID);
+      info.AddValue(_definition.TypeDefinition.Type);
       info.AddHandle(_definition.PropertyName);
       info.AddHandle(_objectID);
     }
diff --git a/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/AssociatedDomainObjectCollectionDataStrategyFactory.cs b/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/AssociatedDomainObjectCollectionDataStrategyFactory.cs
index b28459bfe2..eabea70977 100644
--- a/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/AssociatedDomainObjectCollectionDataStrategyFactory.cs
+++ b/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/AssociatedDomainObjectCollectionDataStrategyFactory.cs
@@ -44,7 +44,7 @@ public IDomainObjectCollectionData CreateDataStrategyForEndPoint (RelationEndPoi
     {
       ArgumentUtility.CheckNotNull("endPointID", endPointID);
 
-      var requiredItemType = endPointID.Definition.GetOppositeEndPointDefinition().ClassDefinition.ClassType;
+      var requiredItemType = endPointID.Definition.GetOppositeEndPointDefinition().TypeDefinition.Type;
       return new ModificationCheckingDomainObjectCollectionDataDecorator(
           requiredItemType, new EndPointDelegatingDomainObjectCollectionData(endPointID, _virtualEndPointProvider));
     }
diff --git a/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/SortedPropertyComparer.cs b/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/SortedPropertyComparer.cs
index 0deb963348..5de6846940 100644
--- a/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/SortedPropertyComparer.cs
+++ b/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/SortedPropertyComparer.cs
@@ -82,7 +82,7 @@ public int Compare (DomainObject? x, DomainObject? y)
       if (dataContainer == null)
         return null;
 
-      if (!SortedPropertySpecification.PropertyDefinition.ClassDefinition.IsSameOrBaseClassOf(dataContainer.ClassDefinition))
+      if (!SortedPropertySpecification.PropertyDefinition.TypeDefinition.IsAssignableFrom(dataContainer.ClassDefinition))
         return null;
 
       return dataContainer.GetValueWithoutEvents(SortedPropertySpecification.PropertyDefinition, ValueAccess);
diff --git a/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/VirtualCollectionEndPointCollectionProvider.cs b/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/VirtualCollectionEndPointCollectionProvider.cs
index e5a1a21439..47ca6c9dce 100644
--- a/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/VirtualCollectionEndPointCollectionProvider.cs
+++ b/Remotion/Data/DomainObjects/DataManagement/RelationEndPoints/VirtualEndPoints/CollectionEndPoints/VirtualCollectionEndPointCollectionProvider.cs
@@ -57,7 +57,7 @@ public IObjectList<IDomainObject> GetCollection (RelationEndPointID endPointID)
 
     private IObjectList<IDomainObject> GetCollectionWithoutCache (RelationEndPointID endPointID)
     {
-      var requiredItemType = endPointID.Definition.GetOppositeEndPointDefinition().ClassDefinition.ClassType;
+      var requiredItemType = endPointID.Definition.GetOppositeEndPointDefinition().TypeDefinition.Type;
       var dataStrategy = new EndPointDelegatingVirtualCollectionData(endPointID, requiredItemType, _virtualEndPointProvider);
       return ObjectListFactory.Create(dataStrategy);
     }
diff --git a/Remotion/Data/DomainObjects/DomainImplementation/Cloning/DomainObjectCloner.cs b/Remotion/Data/DomainObjects/DomainImplementation/Cloning/DomainObjectCloner.cs
index e69c3a74b2..1de1c07900 100644
--- a/Remotion/Data/DomainObjects/DomainImplementation/Cloning/DomainObjectCloner.cs
+++ b/Remotion/Data/DomainObjects/DomainImplementation/Cloning/DomainObjectCloner.cs
@@ -77,8 +77,8 @@ public virtual T CreateValueClone<T> (T source)
     public virtual T CreateCloneHull<T> (T source)
         where T : DomainObject
     {
-      var classType = source.ID.ClassDefinition.ClassType;
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(classType);
+      var type = source.ID.ClassDefinition.Type;
+      var classDefinition = MappingConfiguration.Current.GetClassDefinition(type);
 
       // Get an object reference for a non-existing object, then register a new DataContainer for it. This, in effect, creates a New object that has
       // no ctor called.
diff --git a/Remotion/Data/DomainObjects/DomainImplementation/Transport/XmlTransportItem.cs b/Remotion/Data/DomainObjects/DomainImplementation/Transport/XmlTransportItem.cs
index 80bb5c9612..53f25c3cdb 100644
--- a/Remotion/Data/DomainObjects/DomainImplementation/Transport/XmlTransportItem.cs
+++ b/Remotion/Data/DomainObjects/DomainImplementation/Transport/XmlTransportItem.cs
@@ -99,30 +99,30 @@ private void SerializeProperties (XmlWriter writer)
       writer.WriteEndElement();
     }
 
-    private List<KeyValuePair<string, object?>> DeserializeProperties (XmlReader reader, ClassDefinition classDefinition)
+    private List<KeyValuePair<string, object?>> DeserializeProperties (XmlReader reader, TypeDefinition typeDefinition)
     {
       reader.ReadStartElement("Properties");
       var properties = new List<KeyValuePair<string, object?>>();
       while (reader.IsStartElement("Property"))
-        properties.Add(DeserializeProperty(reader, classDefinition));
+        properties.Add(DeserializeProperty(reader, typeDefinition));
       reader.ReadEndElement();
       return properties;
     }
 
-    private void SerializeProperty (XmlWriter writer, ClassDefinition classDefinition, KeyValuePair<string, object?> property)
+    private void SerializeProperty (XmlWriter writer, TypeDefinition typeDefinition, KeyValuePair<string, object?> property)
     {
-      PropertyDefinition? propertyDefinition = classDefinition.GetPropertyDefinition(property.Key);
+      PropertyDefinition? propertyDefinition = typeDefinition.GetPropertyDefinition(property.Key);
       writer.WriteStartElement("Property");
       writer.WriteAttributeString("Name", property.Key);
       SerializePropertyValue(writer, propertyDefinition, property.Value);
       writer.WriteEndElement();
     }
 
-    private KeyValuePair<string, object?> DeserializeProperty (XmlReader reader, ClassDefinition classDefinition)
+    private KeyValuePair<string, object?> DeserializeProperty (XmlReader reader, TypeDefinition typeDefinition)
     {
       string? name = reader.GetAttribute("Name");
       Assertion.IsNotNull(name, "No value was found for required attribute 'Name' on the current node.");
-      PropertyDefinition? propertyDefinition = classDefinition.GetPropertyDefinition(name);
+      PropertyDefinition? propertyDefinition = typeDefinition.GetPropertyDefinition(name);
       object? value = DeserializePropertyValue(reader, propertyDefinition);
       return new KeyValuePair<string, object?>(name, value);
     }
diff --git a/Remotion/Data/DomainObjects/DomainObjectHandle.cs b/Remotion/Data/DomainObjects/DomainObjectHandle.cs
index 4d6493047d..f8488dada5 100644
--- a/Remotion/Data/DomainObjects/DomainObjectHandle.cs
+++ b/Remotion/Data/DomainObjects/DomainObjectHandle.cs
@@ -34,7 +34,7 @@ public class DomainObjectHandle<T> : IDomainObjectHandle<T>
     public DomainObjectHandle (ObjectID objectID)
     {
       ArgumentUtility.CheckNotNull("objectID", objectID);
-      if (objectID.ClassDefinition.ClassType != typeof(T))
+      if (objectID.ClassDefinition.Type != typeof(T))
       {
         var message = string.Format("The class type of ObjectID '{0}' doesn't match the handle type '{1}'.", objectID, typeof(T));
         throw new ArgumentException(message, "objectID");
diff --git a/Remotion/Data/DomainObjects/DomainObjectState.cs b/Remotion/Data/DomainObjects/DomainObjectState.cs
index a0485c160c..441357ef70 100644
--- a/Remotion/Data/DomainObjects/DomainObjectState.cs
+++ b/Remotion/Data/DomainObjects/DomainObjectState.cs
@@ -60,7 +60,7 @@ private enum Flags
       /// Represents a <see cref="DataContainer"/> where at least one <see cref="PropertyDefinition"/> with
       /// <see cref="PropertyDefinition.StorageClass"/>.<see cref="StorageClass.Persistent"/> has a <see cref="PropertyValue"/> with <see cref="PropertyValue.Value"/> not equal to
       /// <see cref="PropertyValue.OriginalValue"/> or the <see cref="DataContainer"/>.<see cref="DataContainer.HasBeenMarkedChanged"/> flag has been set for a
-      /// <see cref="DomainObject"/> with the <see cref="ClassDefinition"/>.<see cref="ClassDefinitionExtensions.IsNonPersistent"/> flag set to <see langword="false" />.
+      /// <see cref="DomainObject"/> with the <see cref="ClassDefinition"/>.<see cref="TypeDefinitionExtensions.IsNonPersistent"/> flag set to <see langword="false" />.
       /// </summary>
       PersistentDataChanged = 1 << 7,
 
@@ -69,7 +69,7 @@ private enum Flags
       /// Represents a <see cref="DataContainer"/> where at least one <see cref="PropertyDefinition"/> with
       /// <see cref="PropertyDefinition.StorageClass"/>.<see cref="StorageClass.Transaction"/> has a <see cref="PropertyValue"/> with <see cref="PropertyValue.Value"/> not equal to
       /// <see cref="PropertyValue.OriginalValue"/> or the <see cref="DataContainer"/>.<see cref="DataContainer.HasBeenMarkedChanged"/> flag has been set for a
-      /// <see cref="DomainObject"/> with the <see cref="ClassDefinition"/>.<see cref="ClassDefinitionExtensions.IsNonPersistent"/> flag set to <see langword="true" />.
+      /// <see cref="DomainObject"/> with the <see cref="ClassDefinition"/>.<see cref="TypeDefinitionExtensions.IsNonPersistent"/> flag set to <see langword="true" />.
       /// </summary>
       NonPersistentDataChanged = 1 << 8,
 
diff --git a/Remotion/Data/DomainObjects/Infrastructure/ObjectLifetime/ObjectLifetimeAgent.cs b/Remotion/Data/DomainObjects/Infrastructure/ObjectLifetime/ObjectLifetimeAgent.cs
index 2533a2c4be..c79ded1094 100644
--- a/Remotion/Data/DomainObjects/Infrastructure/ObjectLifetime/ObjectLifetimeAgent.cs
+++ b/Remotion/Data/DomainObjects/Infrastructure/ObjectLifetime/ObjectLifetimeAgent.cs
@@ -102,9 +102,9 @@ public DomainObject NewObject (ClassDefinition classDefinition, ParamList constr
         throw new InvalidOperationException(
             string.Format(
                 "Cannot instantiate type '{0}' because it is abstract. For classes with automatic properties, InstantiableAttribute must be used.",
-                classDefinition.ClassType));
+                classDefinition.Type));
 
-      _eventSink.RaiseNewObjectCreatingEvent(classDefinition.ClassType);
+      _eventSink.RaiseNewObjectCreatingEvent(classDefinition.Type);
 
       var objectID = _persistenceStrategy.CreateNewObjectID(classDefinition);
       var initializationContext = new NewObjectInitializationContext(
diff --git a/Remotion/Data/DomainObjects/Infrastructure/PropertyAccessorData.cs b/Remotion/Data/DomainObjects/Infrastructure/PropertyAccessorData.cs
index 41a5ca6577..a1dec46ca6 100644
--- a/Remotion/Data/DomainObjects/Infrastructure/PropertyAccessorData.cs
+++ b/Remotion/Data/DomainObjects/Infrastructure/PropertyAccessorData.cs
@@ -24,21 +24,21 @@ namespace Remotion.Data.DomainObjects.Infrastructure
   public class PropertyAccessorData
   {
     /// <summary>
-    /// Gets the <see cref="PropertyKind"/> for a given property identifier and class definition.
+    /// Gets the <see cref="PropertyKind"/> for a given property identifier and type definition.
     /// </summary>
-    /// <param name="classDefinition">The <see cref="Mapping.ClassDefinition"/> object describing the property's declaring class.</param>
+    /// <param name="typeDefinition">The <see cref="TypeDefinition"/> object describing the property's declaring type.</param>
     /// <param name="propertyIdentifier">The property identifier.</param>
     /// <returns>The <see cref="PropertyKind"/> of the property.</returns>
     /// <exception cref="ArgumentNullException">One of the method's arguments is <see langword="null"/>.</exception>
     /// <exception cref="ArgumentException">The domain object does not have a property with the given identifier.</exception>
-    public static PropertyKind GetPropertyKind (ClassDefinition classDefinition, string propertyIdentifier)
+    public static PropertyKind GetPropertyKind (TypeDefinition typeDefinition, string propertyIdentifier)
     {
       // TODO RM-8246: possibly inline this method
 
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNull("propertyIdentifier", propertyIdentifier);
 
-      Tuple<PropertyDefinition?, IRelationEndPointDefinition?> propertyObjects = GetPropertyDefinitionObjects(classDefinition, propertyIdentifier);
+      Tuple<PropertyDefinition?, IRelationEndPointDefinition?> propertyObjects = GetPropertyDefinitionObjects(typeDefinition, propertyIdentifier);
       return GetPropertyKind(propertyObjects.Item2);
     }
 
@@ -69,24 +69,24 @@ private static IPropertyAccessorStrategy GetStrategy (PropertyKind kind)
     /// <summary>
     /// Returns the value type of the given property.
     /// </summary>
-    /// <param name="classDefinition">The <see cref="Mapping.ClassDefinition"/> object describing the property's declaring class.</param>
+    /// <param name="typeDefinition">The <see cref="Mapping.TypeDefinition"/> object describing the property's declaring type.</param>
     /// <param name="propertyIdentifier">The property identifier.</param>
     /// <returns>The property's value type.</returns>
     /// <remarks>For simple value properties, this returns the simple property type. For related objects, it
     /// returns the related object's type. For related object collections, it returns type <see cref="ObjectList{T}"/>, where "T" is the related
     /// objects' type.</remarks>
     /// <exception cref="ArgumentNullException">One of the method's arguments is <see langword="null"/>.</exception>
-    /// <exception cref="ArgumentException">The class definition does not have a property with the given identifier.</exception>
-    public static Type GetPropertyType (ClassDefinition classDefinition, string propertyIdentifier)
+    /// <exception cref="ArgumentException">The type definition does not have a property with the given identifier.</exception>
+    public static Type GetPropertyType (TypeDefinition typeDefinition, string propertyIdentifier)
     {
       // TODO RM-8246: possibly inline this method
 
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNull("propertyIdentifier", propertyIdentifier);
 
       // TODO RM-8246: this is actually a discriminating union, solved via nullable values
       Tuple<PropertyDefinition?, IRelationEndPointDefinition?> definitionObjects =
-          GetPropertyDefinitionObjects(classDefinition, propertyIdentifier);
+          GetPropertyDefinitionObjects(typeDefinition, propertyIdentifier);
 
       return GetStrategy(GetPropertyKind(definitionObjects.Item2)).GetPropertyType(definitionObjects.Item1, definitionObjects.Item2);
     }
@@ -94,28 +94,28 @@ public static Type GetPropertyType (ClassDefinition classDefinition, string prop
     /// <summary>
     /// Returns mapping objects for the given property.
     /// </summary>
-    /// <param name="classDefinition">The <see cref="Mapping.ClassDefinition"/> object describing the property's declaring class.</param>
+    /// <param name="typeDefinition">The <see cref="Mapping.TypeDefinition"/> object describing the property's declaring type.</param>
     /// <param name="propertyIdentifier">The property identifier.</param>
     /// <returns>The property's <see cref="Mapping.PropertyDefinition"/> and <see cref="IRelationEndPointDefinition"/> objects.</returns>
     /// <exception cref="ArgumentNullException">One of the method's arguments is <see langword="null"/>.</exception>
-    /// <exception cref="ArgumentException">The class definition does not have a property with the given identifier.</exception>
+    /// <exception cref="ArgumentException">The type definition does not have a property with the given identifier.</exception>
     public static Tuple<PropertyDefinition?, IRelationEndPointDefinition?> GetPropertyDefinitionObjects (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyIdentifier)
     {
       // TODO RM-8246: possibly inline this method
 
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNull("propertyIdentifier", propertyIdentifier);
 
-      PropertyDefinition? propertyDefinition = classDefinition.GetPropertyDefinition(propertyIdentifier);
-      IRelationEndPointDefinition? relationEndPointDefinition = classDefinition.GetRelationEndPointDefinition(propertyIdentifier);
+      PropertyDefinition? propertyDefinition = typeDefinition.GetPropertyDefinition(propertyIdentifier);
+      IRelationEndPointDefinition? relationEndPointDefinition = typeDefinition.GetRelationEndPointDefinition(propertyIdentifier);
 
       if (propertyDefinition == null && relationEndPointDefinition == null)
       {
         string message = String.Format(
             "The domain object type {0} does not have a mapping property named '{1}'.",
-            classDefinition.ClassType.GetFullNameSafe(),
+            typeDefinition.Type.GetFullNameSafe(),
             propertyIdentifier);
 
         throw new ArgumentException(message, "propertyIdentifier");
@@ -129,20 +129,20 @@ public static Type GetPropertyType (ClassDefinition classDefinition, string prop
 
     private readonly PropertyDefinition? _propertyDefinition;
     private readonly IRelationEndPointDefinition? _relationEndPointDefinition;
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
     private readonly Type _propertyType;
 
     private readonly IPropertyAccessorStrategy _strategy;
 
-    public PropertyAccessorData (ClassDefinition classDefinition, string propertyIdentifier)
+    public PropertyAccessorData (TypeDefinition typeDefinition, string propertyIdentifier)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNullOrEmpty("propertyIdentifier", propertyIdentifier);
 
       _propertyIdentifier = propertyIdentifier;
-      _classDefinition = classDefinition;
+      _typeDefinition = typeDefinition;
 
-      Tuple<PropertyDefinition?, IRelationEndPointDefinition?> propertyObjects = GetPropertyDefinitionObjects(_classDefinition, propertyIdentifier);
+      Tuple<PropertyDefinition?, IRelationEndPointDefinition?> propertyObjects = GetPropertyDefinitionObjects(_typeDefinition, propertyIdentifier);
       _propertyDefinition = propertyObjects.Item1;
       _relationEndPointDefinition = propertyObjects.Item2;
 
@@ -154,11 +154,11 @@ public PropertyAccessorData (ClassDefinition classDefinition, string propertyIde
     }
 
     /// <summary>
-    /// The definition object for the property's declaring class.
+    /// The definition object for the property's declaring type.
     /// </summary>
-    public ClassDefinition ClassDefinition
+    public TypeDefinition TypeDefinition
     {
-      get { return _classDefinition; }
+      get { return _typeDefinition; }
     }
 
     /// <summary>
@@ -210,24 +210,24 @@ internal IPropertyAccessorStrategy GetStrategy ()
 
     /// <summary>
     /// Determines whether the specified <see cref="T:System.Object"/> is equal to the current <see cref="PropertyAccessorData"/> by comparing
-    /// <see cref="PropertyIdentifier"/> and <see cref="ClassDefinition"/>.
+    /// <see cref="PropertyIdentifier"/> and <see cref="TypeDefinition"/>.
     /// </summary>
     /// <param name="obj">The <see cref="T:System.Object"/> to compare with the current <see cref="PropertyAccessorData"/>.</param>
     /// <returns>
     /// true if the specified <see cref="T:System.Object"/> is equivalent to the current <see cref="PropertyAccessorData"/>, ie. it is another
-    /// instance of <see cref="PropertyAccessorData"/> with equal <see cref="PropertyIdentifier"/> and <see cref="ClassDefinition"/>; otherwise, false.
+    /// instance of <see cref="PropertyAccessorData"/> with equal <see cref="PropertyIdentifier"/> and <see cref="TypeDefinition"/>; otherwise, false.
     /// </returns>
     public override bool Equals (object? obj)
     {
       var other = obj as PropertyAccessorData;
       return other != null
           && Equals(PropertyIdentifier, other.PropertyIdentifier)
-          && Equals(ClassDefinition, other.ClassDefinition);
+          && Equals(TypeDefinition, other.TypeDefinition);
     }
 
     public override int GetHashCode ()
     {
-      return EqualityUtility.GetRotatedHashCode(PropertyIdentifier, ClassDefinition);
+      return EqualityUtility.GetRotatedHashCode(PropertyIdentifier, TypeDefinition);
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects/Infrastructure/PropertyIndexer.cs b/Remotion/Data/DomainObjects/Infrastructure/PropertyIndexer.cs
index c309e5b551..1686019fc0 100644
--- a/Remotion/Data/DomainObjects/Infrastructure/PropertyIndexer.cs
+++ b/Remotion/Data/DomainObjects/Infrastructure/PropertyIndexer.cs
@@ -293,7 +293,7 @@ public PropertyAccessor Find<TDomainObject> ([CanBeNull] TDomainObject thisDomai
     public PropertyAccessor Find ([NotNull] string shortPropertyName)
     {
       ArgumentUtility.CheckNotNullOrEmpty("shortPropertyName", shortPropertyName);
-      return Find(ClassDefinition.ClassType, shortPropertyName);
+      return Find(ClassDefinition.Type, shortPropertyName);
     }
 
     /// <summary>
diff --git a/Remotion/Data/DomainObjects/Infrastructure/RelatedObjectPropertyAccessorStrategy.cs b/Remotion/Data/DomainObjects/Infrastructure/RelatedObjectPropertyAccessorStrategy.cs
index d279e4a253..5ccfc808d3 100644
--- a/Remotion/Data/DomainObjects/Infrastructure/RelatedObjectPropertyAccessorStrategy.cs
+++ b/Remotion/Data/DomainObjects/Infrastructure/RelatedObjectPropertyAccessorStrategy.cs
@@ -137,7 +137,7 @@ public void SetValueWithoutTypeCheck (PropertyAccessor propertyAccessor, ClientT
 
     private void CheckNewRelatedObjectType (IObjectEndPoint objectEndPoint, DomainObject newRelatedObject)
     {
-      if (!objectEndPoint.Definition.GetOppositeEndPointDefinition().ClassDefinition.IsSameOrBaseClassOf(newRelatedObject.ID.ClassDefinition))
+      if (!objectEndPoint.Definition.GetOppositeEndPointDefinition().TypeDefinition.IsAssignableFrom(newRelatedObject.ID.ClassDefinition))
       {
         var message = string.Format(
             "DomainObject '{0}' cannot be assigned to property '{1}' of DomainObject '{2}', because it is not compatible with the type of the property.",
diff --git a/Remotion/Data/DomainObjects/Infrastructure/TypePipe/TypeDefinitionProvider.cs b/Remotion/Data/DomainObjects/Infrastructure/TypePipe/ClassDefinitionProvider.cs
similarity index 69%
rename from Remotion/Data/DomainObjects/Infrastructure/TypePipe/TypeDefinitionProvider.cs
rename to Remotion/Data/DomainObjects/Infrastructure/TypePipe/ClassDefinitionProvider.cs
index 5aff643ea3..a0558bc3fd 100644
--- a/Remotion/Data/DomainObjects/Infrastructure/TypePipe/TypeDefinitionProvider.cs
+++ b/Remotion/Data/DomainObjects/Infrastructure/TypePipe/ClassDefinitionProvider.cs
@@ -22,22 +22,22 @@
 namespace Remotion.Data.DomainObjects.Infrastructure.TypePipe
 {
   /// <summary>
-  /// Implements <see cref="ITypeDefinitionProvider"/> by retrieving the <see cref="ClassDefinition"/> of the domain object type from the current 
+  /// Implements <see cref="IClassDefinitionProvider"/> by retrieving the <see cref="ClassDefinition"/> of the domain object type from the current 
   /// mapping configuration.
   /// </summary>
   /// <threadsafety static="true" instance="true"/>
-  [ImplementationFor(typeof(ITypeDefinitionProvider), Lifetime = LifetimeKind.Singleton, RegistrationType = RegistrationType.Single)]
-  public class TypeDefinitionProvider : ITypeDefinitionProvider
+  [ImplementationFor(typeof(IClassDefinitionProvider), Lifetime = LifetimeKind.Singleton, RegistrationType = RegistrationType.Single)]
+  public class ClassDefinitionProvider : IClassDefinitionProvider
   {
-    public ClassDefinition? GetTypeDefinition (Type domainObjectType)
+    public ClassDefinition? GetClassDefinition (Type domainObjectType)
     {
       ArgumentUtility.CheckNotNull("domainObjectType", domainObjectType);
 
       var mappingConfiguration = MappingConfiguration.Current;
-      if (!mappingConfiguration.ContainsTypeDefinition(domainObjectType))
+      if (!mappingConfiguration.ContainsClassDefinition(domainObjectType))
         return null;
 
-      return mappingConfiguration.GetTypeDefinition(domainObjectType);
+      return mappingConfiguration.GetClassDefinition(domainObjectType);
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects/Infrastructure/TypePipe/DomainObjectCreator.cs b/Remotion/Data/DomainObjects/Infrastructure/TypePipe/DomainObjectCreator.cs
index ae76437a0c..e9908878cb 100644
--- a/Remotion/Data/DomainObjects/Infrastructure/TypePipe/DomainObjectCreator.cs
+++ b/Remotion/Data/DomainObjects/Infrastructure/TypePipe/DomainObjectCreator.cs
@@ -61,10 +61,10 @@ public DomainObject CreateObjectReference (IObjectInitializationContext objectIn
       ArgumentUtility.CheckNotNull("clientTransaction", clientTransaction);
 
       var objectID = objectInitializationContext.ObjectID;
-      CheckDomainTypeAndClassDefinition(objectID.ClassDefinition.ClassType);
+      CheckDomainTypeAndClassDefinition(objectID.ClassDefinition.Type);
       objectID.ClassDefinition.ValidateCurrentMixinConfiguration();
 
-      var concreteType = Pipeline.ReflectionService.GetAssembledType(objectID.ClassDefinition.ClassType);
+      var concreteType = Pipeline.ReflectionService.GetAssembledType(objectID.ClassDefinition.Type);
 #if NETFRAMEWORK
       var instance = (DomainObject)FormatterServices.GetSafeUninitializedObject(concreteType);
 #else
@@ -91,9 +91,9 @@ public DomainObject CreateNewObject (IObjectInitializationContext objectInitiali
       ArgumentUtility.CheckNotNull("constructorParameters", constructorParameters);
       ArgumentUtility.CheckNotNull("clientTransaction", clientTransaction);
 
-      var domainObjectType = objectInitializationContext.ObjectID.ClassDefinition.ClassType;
+      var domainObjectType = objectInitializationContext.ObjectID.ClassDefinition.Type;
       CheckDomainTypeAndClassDefinition(domainObjectType);
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(domainObjectType);
+      var classDefinition = MappingConfiguration.Current.GetClassDefinition(domainObjectType);
       classDefinition.ValidateCurrentMixinConfiguration();
 
       using (clientTransaction.EnterNonDiscardingScope())
@@ -115,13 +115,13 @@ private void CheckDomainTypeAndClassDefinition (Type domainObjectType)
         throw new NonInterceptableTypeException(message, domainObjectType);
       }
 
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(domainObjectType);
+      var classDefinition = MappingConfiguration.Current.GetClassDefinition(domainObjectType);
       if (classDefinition.IsAbstract)
       {
         var message1 = string.Format(
             "Cannot instantiate type '{0}' as it is abstract; for classes with automatic properties, InstantiableAttribute must be used.",
-            classDefinition.ClassType.GetFullNameSafe());
-        throw new NonInterceptableTypeException(message1, classDefinition.ClassType);
+            classDefinition.Type.GetFullNameSafe());
+        throw new NonInterceptableTypeException(message1, classDefinition.Type);
       }
     }
   }
diff --git a/Remotion/Data/DomainObjects/Infrastructure/TypePipe/DomainObjectParticipant.cs b/Remotion/Data/DomainObjects/Infrastructure/TypePipe/DomainObjectParticipant.cs
index b027fac58e..92f61401d4 100644
--- a/Remotion/Data/DomainObjects/Infrastructure/TypePipe/DomainObjectParticipant.cs
+++ b/Remotion/Data/DomainObjects/Infrastructure/TypePipe/DomainObjectParticipant.cs
@@ -54,9 +54,9 @@ static DomainObjectParticipant ()
     }
 
     [Obsolete("Use constructor instead. (Version 1.17.13")]
-    public static DomainObjectParticipant Create (ITypeDefinitionProvider typeDefinitionProvider, IInterceptedPropertyFinder interceptedPropertyFinder)
+    public static DomainObjectParticipant Create (IClassDefinitionProvider classDefinitionProvider, IInterceptedPropertyFinder interceptedPropertyFinder)
     {
-      return new DomainObjectParticipant(typeDefinitionProvider, interceptedPropertyFinder);
+      return new DomainObjectParticipant(classDefinitionProvider, interceptedPropertyFinder);
     }
 
     private static readonly Type s_domainObjectBaseType = typeof(DomainObject);
@@ -72,15 +72,15 @@ private static MethodInfo GetInfrastructureHook (string name)
       return method;
     }
 
-    private readonly ITypeDefinitionProvider _typeDefinitionProvider;
+    private readonly IClassDefinitionProvider _classDefinitionProvider;
     private readonly IInterceptedPropertyFinder _interceptedPropertyFinder;
 
-    public DomainObjectParticipant (ITypeDefinitionProvider typeDefinitionProvider, IInterceptedPropertyFinder interceptedPropertyFinder)
+    public DomainObjectParticipant (IClassDefinitionProvider classDefinitionProvider, IInterceptedPropertyFinder interceptedPropertyFinder)
     {
-      ArgumentUtility.CheckNotNull("typeDefinitionProvider", typeDefinitionProvider);
+      ArgumentUtility.CheckNotNull("classDefinitionProvider", classDefinitionProvider);
       ArgumentUtility.CheckNotNull("interceptedPropertyFinder", interceptedPropertyFinder);
 
-      _typeDefinitionProvider = typeDefinitionProvider;
+      _classDefinitionProvider = classDefinitionProvider;
       _interceptedPropertyFinder = interceptedPropertyFinder;
     }
 
@@ -106,7 +106,7 @@ public void Participate (object id, IProxyTypeAssemblyContext proxyTypeAssemblyC
       var proxyType = proxyTypeAssemblyContext.ProxyType;
       var domainObjectType = proxyTypeAssemblyContext.RequestedType;
 
-      var classDefinition = _typeDefinitionProvider.GetTypeDefinition(domainObjectType);
+      var classDefinition = _classDefinitionProvider.GetClassDefinition(domainObjectType);
       if (classDefinition == null || classDefinition.IsAbstract)
         return;
 
@@ -128,7 +128,7 @@ public void HandleNonSubclassableType (Type nonSubclassableRequestedType)
       if (!s_domainObjectBaseType.IsTypePipeAssignableFrom(nonSubclassableRequestedType))
         return;
 
-      var classDefinition = _typeDefinitionProvider.GetTypeDefinition(nonSubclassableRequestedType);
+      var classDefinition = _classDefinitionProvider.GetClassDefinition(nonSubclassableRequestedType);
       if (classDefinition != null && !classDefinition.IsAbstract)
       {
         var message = string.Format("The requested type '{0}' is derived from DomainObject but cannot be subclassed.", nonSubclassableRequestedType.Name);
diff --git a/Remotion/Data/DomainObjects/Infrastructure/TypePipe/ITypeDefinitionProvider.cs b/Remotion/Data/DomainObjects/Infrastructure/TypePipe/IClassDefinitionProvider.cs
similarity index 91%
rename from Remotion/Data/DomainObjects/Infrastructure/TypePipe/ITypeDefinitionProvider.cs
rename to Remotion/Data/DomainObjects/Infrastructure/TypePipe/IClassDefinitionProvider.cs
index c53e3f69bf..8d30d52e94 100644
--- a/Remotion/Data/DomainObjects/Infrastructure/TypePipe/ITypeDefinitionProvider.cs
+++ b/Remotion/Data/DomainObjects/Infrastructure/TypePipe/IClassDefinitionProvider.cs
@@ -24,9 +24,9 @@ namespace Remotion.Data.DomainObjects.Infrastructure.TypePipe
   /// Defines an interface for classes retrieving the non-abstract <see cref="ClassDefinition"/> for a domain object type.
   /// </summary>
   /// <threadsafety static="true" instance="true"/>
-  public interface ITypeDefinitionProvider
+  public interface IClassDefinitionProvider
   {
     [CanBeNull]
-    ClassDefinition? GetTypeDefinition (Type domainObjectType);
+    ClassDefinition? GetClassDefinition (Type domainObjectType);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Infrastructure/TypePipe/InterceptedPropertyCollector.cs b/Remotion/Data/DomainObjects/Infrastructure/TypePipe/InterceptedPropertyCollector.cs
index bb90463570..5c5af6dbdc 100644
--- a/Remotion/Data/DomainObjects/Infrastructure/TypePipe/InterceptedPropertyCollector.cs
+++ b/Remotion/Data/DomainObjects/Infrastructure/TypePipe/InterceptedPropertyCollector.cs
@@ -53,7 +53,7 @@ public InterceptedPropertyCollector (ClassDefinition classDefinition, ITypeConve
 
       _classDefinition = classDefinition;
       _typeConversionProvider = typeConversionProvider;
-      _baseType = classDefinition.ClassType;
+      _baseType = classDefinition.Type;
 
       if (_classDefinition.IsAbstract)
       {
diff --git a/Remotion/Data/DomainObjects/Linq/DomainObjectQueryGenerator.cs b/Remotion/Data/DomainObjects/Linq/DomainObjectQueryGenerator.cs
index 90c54bb72d..890e97f365 100644
--- a/Remotion/Data/DomainObjects/Linq/DomainObjectQueryGenerator.cs
+++ b/Remotion/Data/DomainObjects/Linq/DomainObjectQueryGenerator.cs
@@ -48,10 +48,10 @@ private abstract class GenericCallHelper
     {
       private static readonly ConcurrentDictionary<Type, GenericCallHelper> s_cache = new ConcurrentDictionary<Type, GenericCallHelper>();
 
-      public static GenericCallHelper Create (Type classType)
+      public static GenericCallHelper Create (Type type)
       {
         return s_cache.GetOrAdd(
-            classType,
+            type,
             key => (GenericCallHelper)Activator.CreateInstance(typeof(GenericCallHelper<>).MakeGenericType(key))!);
       }
 
@@ -163,10 +163,10 @@ public virtual IExecutableQuery<IEnumerable<TItem>> CreateSequenceQuery<TItem> (
       if (queryType == QueryType.Collection)
       {
         Assertion.DebugIsNotNull(sqlQuery.SelectedEntityType, "sqlQuery.SelectedEntityType != null");
-        var selectedEntityClassDefinition = _mappingConfiguration.GetTypeDefinition(sqlQuery.SelectedEntityType);
-        Assertion.IsNotNull(selectedEntityClassDefinition, "We assume that in a re-store LINQ query, entities always have a mapping.");
+        var selectedEntityTypeDefinition = _mappingConfiguration.GetTypeDefinition(sqlQuery.SelectedEntityType);
+        Assertion.IsNotNull(selectedEntityTypeDefinition, "We assume that in a re-store LINQ query, entities always have a mapping.");
 
-        var fetchQueries = CreateEagerFetchQueries(selectedEntityClassDefinition, fetchQueryModelBuilders);
+        var fetchQueries = CreateEagerFetchQueries(selectedEntityTypeDefinition, fetchQueryModelBuilders);
         foreach (var fetchQuery in fetchQueries)
           query.EagerFetchQueries.Add(fetchQuery.Item1, fetchQuery.Item2);
 
@@ -208,12 +208,12 @@ protected virtual IQuery CreateQuery (
     }
 
     private IEnumerable<Tuple<IRelationEndPointDefinition, IQuery>> CreateEagerFetchQueries (
-        ClassDefinition previousClassDefinition,
+        TypeDefinition previousTypeDefinition,
         IEnumerable<FetchQueryModelBuilder> fetchQueryModelBuilders)
     {
       foreach (var fetchQueryModelBuilder in fetchQueryModelBuilders)
       {
-        var relationEndPointDefinition = GetEagerFetchRelationEndPointDefinition(fetchQueryModelBuilder.FetchRequest, previousClassDefinition);
+        var relationEndPointDefinition = GetEagerFetchRelationEndPointDefinition(fetchQueryModelBuilder.FetchRequest, previousTypeDefinition);
 
         // clone the fetch query model because we don't want to modify the source model of all inner requests
         var fetchQueryModel = fetchQueryModelBuilder.GetOrCreateFetchQueryModel().Clone();
@@ -237,12 +237,12 @@ private IEnumerable<Tuple<IRelationEndPointDefinition, IQuery>> CreateEagerFetch
           fetchQueryModel.BodyClauses.Add(orderByClause);
         }
 
-        var fetchedClassType = relationEndPointDefinition.GetOppositeClassDefinition().ClassType;
-        var genericCallHelper = GenericCallHelper.Create(fetchedClassType);
+        var fetchedType = relationEndPointDefinition.GetOppositeTypeDefinition().Type;
+        var genericCallHelper = GenericCallHelper.Create(fetchedType);
         var fetchQuery = genericCallHelper.CreateSequenceQuery(
             this,
             "<fetch query for " + fetchQueryModelBuilder.FetchRequest.RelationMember.Name + ">",
-            previousClassDefinition.StorageEntityDefinition.StorageProviderDefinition,
+            previousTypeDefinition.StorageEntityDefinition.StorageProviderDefinition,
             fetchQueryModel,
             fetchQueryModelBuilder.CreateInnerBuilders());
 
@@ -261,7 +261,7 @@ private IEnumerable<Tuple<IRelationEndPointDefinition, IQuery>> CreateEagerFetch
       }
     }
 
-    private IRelationEndPointDefinition GetEagerFetchRelationEndPointDefinition (FetchRequestBase fetchRequest, ClassDefinition classDefinition)
+    private IRelationEndPointDefinition GetEagerFetchRelationEndPointDefinition (FetchRequestBase fetchRequest, TypeDefinition typeDefinition)
     {
       var propertyInfo = fetchRequest.RelationMember as PropertyInfo;
       if (propertyInfo == null)
@@ -274,10 +274,11 @@ private IRelationEndPointDefinition GetEagerFetchRelationEndPointDefinition (Fet
       }
 
       var propertyInfoAdapter = PropertyInfoAdapter.Create(propertyInfo);
-      var endPoint = classDefinition.ResolveRelationEndPoint(propertyInfoAdapter)
-                     ?? classDefinition.GetAllDerivedClasses()
-                         .Select(cd => cd.ResolveRelationEndPoint(propertyInfoAdapter))
-                         .FirstOrDefault(ep => ep != null);
+      var endPoint = InlineTypeDefinitionWalker.WalkDescendants(
+          typeDefinition,
+          classDefinition => classDefinition.ResolveRelationEndPoint(propertyInfoAdapter),
+          interfaceDefinition => throw new NotImplementedException("Interfaces are not supported."),
+          match: relationEndPoint => relationEndPoint != null); // TODO R2I Mapping: Add support for interfaces
 
       if (endPoint == null)
       {
diff --git a/Remotion/Data/DomainObjects/Linq/IDomainObjectQueryGenerator.cs b/Remotion/Data/DomainObjects/Linq/IDomainObjectQueryGenerator.cs
index 5e66ba7cf5..b941ac6550 100644
--- a/Remotion/Data/DomainObjects/Linq/IDomainObjectQueryGenerator.cs
+++ b/Remotion/Data/DomainObjects/Linq/IDomainObjectQueryGenerator.cs
@@ -33,7 +33,7 @@ namespace Remotion.Data.DomainObjects.Linq
   public interface IDomainObjectQueryGenerator
   {
     /// <summary>
-    /// Creates an <see cref="IExecutableQuery{T}"/> object for a given <see cref="ClassDefinition"/> based on the given <see cref="QueryModel"/>.
+    /// Creates an <see cref="IExecutableQuery{T}"/> object for a given <see cref="TypeDefinition"/> based on the given <see cref="QueryModel"/>.
     /// </summary>
     /// <param name="id">The identifier for the resulting query.</param>
     /// <param name="storageProviderDefinition">The <see cref="StorageProvider"/> for the query.</param>
@@ -44,7 +44,7 @@ public interface IDomainObjectQueryGenerator
     IExecutableQuery<T> CreateScalarQuery<T> (string id, StorageProviderDefinition storageProviderDefinition, QueryModel queryModel);
 
     /// <summary>
-    /// Creates an <see cref="IExecutableQuery{T}"/> collection for a given <see cref="ClassDefinition"/> based on the given <see cref="QueryModel"/>.
+    /// Creates an <see cref="IExecutableQuery{T}"/> collection for a given <see cref="TypeDefinition"/> based on the given <see cref="QueryModel"/>.
     /// </summary>
     /// <param name="id">The identifier for the resulting query.</param>
     /// <param name="storageProviderDefinition">The <see cref="StorageProvider"/> for the query.</param>
diff --git a/Remotion/Data/DomainObjects/Linq/IStorageSpecificExpressionResolver.cs b/Remotion/Data/DomainObjects/Linq/IStorageSpecificExpressionResolver.cs
index 72061b4355..b39806980b 100644
--- a/Remotion/Data/DomainObjects/Linq/IStorageSpecificExpressionResolver.cs
+++ b/Remotion/Data/DomainObjects/Linq/IStorageSpecificExpressionResolver.cs
@@ -27,11 +27,11 @@ namespace Remotion.Data.DomainObjects.Linq
   /// </summary>
   public interface IStorageSpecificExpressionResolver
   {
-    SqlEntityDefinitionExpression ResolveEntity (ClassDefinition classDefinition, string tableAlias);
+    SqlEntityDefinitionExpression ResolveEntity (TypeDefinition typeDefinition, string tableAlias);
     Expression ResolveProperty (SqlEntityExpression originatingEntity, PropertyDefinition propertyDefinition);
-    Expression ResolveIDProperty (SqlEntityExpression originatingEntity, ClassDefinition classDefinition);
+    Expression ResolveIDProperty (SqlEntityExpression originatingEntity, TypeDefinition typeDefinition);
 
-    IResolvedTableInfo ResolveTable (ClassDefinition classDefinition, string tableAlias);
+    IResolvedTableInfo ResolveTable (TypeDefinition typeDefinition, string tableAlias);
 
     ResolvedJoinInfo ResolveJoin (
         SqlEntityExpression originatingEntity, IRelationEndPointDefinition leftEndPoint, IRelationEndPointDefinition rightEndPoint, string tableAlias);
diff --git a/Remotion/Data/DomainObjects/Linq/MappingResolver.cs b/Remotion/Data/DomainObjects/Linq/MappingResolver.cs
index c96cf7aba3..22c67f75d9 100644
--- a/Remotion/Data/DomainObjects/Linq/MappingResolver.cs
+++ b/Remotion/Data/DomainObjects/Linq/MappingResolver.cs
@@ -15,6 +15,7 @@
 // along with re-motion; if not, see http://www.gnu.org/licenses.
 // 
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
@@ -60,8 +61,8 @@ public IResolvedTableInfo ResolveTableInfo (UnresolvedTableInfo tableInfo, Uniqu
       ArgumentUtility.CheckNotNull("tableInfo", tableInfo);
       ArgumentUtility.CheckNotNull("generator", generator);
 
-      var classDefinition = GetClassDefinition(tableInfo.ItemType);
-      return _storageSpecificExpressionResolver.ResolveTable(classDefinition, generator.GetUniqueIdentifier("t"));
+      var typeDefinition = GetTypeDefinition(tableInfo.ItemType);
+      return _storageSpecificExpressionResolver.ResolveTable(typeDefinition, generator.GetUniqueIdentifier("t"));
     }
 
     public ResolvedJoinInfo ResolveJoinInfo (UnresolvedJoinInfo joinInfo, UniqueIdentifierGenerator generator)
@@ -83,8 +84,8 @@ public SqlEntityDefinitionExpression ResolveSimpleTableInfo (IResolvedTableInfo
       ArgumentUtility.CheckNotNull("tableInfo", tableInfo);
       ArgumentUtility.CheckNotNull("generator", generator);
 
-      var classDefinition = GetClassDefinition(tableInfo.ItemType);
-      return _storageSpecificExpressionResolver.ResolveEntity(classDefinition, tableInfo.TableAlias);
+      var typeDefinition = GetTypeDefinition(tableInfo.ItemType);
+      return _storageSpecificExpressionResolver.ResolveEntity(typeDefinition, tableInfo.TableAlias);
     }
 
     public Expression ResolveMemberExpression (SqlEntityExpression originatingEntity, MemberInfo memberInfo)
@@ -93,15 +94,16 @@ public Expression ResolveMemberExpression (SqlEntityExpression originatingEntity
       ArgumentUtility.CheckNotNull("memberInfo", memberInfo);
 
       var property = GetMemberAsProperty(originatingEntity, memberInfo);
-      var entityClassDefinition = GetClassDefinition(originatingEntity.Type);
+      var entityTypeDefinition = GetTypeDefinition(originatingEntity.Type);
 
       if (property.Equals(s_idProperty))
-        return _storageSpecificExpressionResolver.ResolveIDProperty(originatingEntity, entityClassDefinition);
+        return _storageSpecificExpressionResolver.ResolveIDProperty(originatingEntity, entityTypeDefinition);
 
-      var allClassDefinitions = new[] { entityClassDefinition }.Concat(entityClassDefinition.GetAllDerivedClasses());
-      var resolvedMember = allClassDefinitions
-          .Select(cd => ResolveMemberInClassDefinition(originatingEntity, property, cd))
-          .FirstOrDefault(e => e != null);
+      var resolvedMember = InlineTypeDefinitionWalker.WalkDescendants(
+          entityTypeDefinition,
+          classDefinition => ResolveMemberInTypeDefinition(originatingEntity, property, classDefinition),
+          interfaceDefinition => throw new NotImplementedException("Interfaces are not supported"),
+          match: expression => expression != null); // TODO R2I Mapping: Add support for interfaces
 
       if (resolvedMember == null)
       {
@@ -156,13 +158,17 @@ public Expression ResolveTypeCheck (Expression checkedExpression, Type desiredTy
           throw new UnmappedItemException(message);
         }
 
-        var classDefinition = GetClassDefinition(desiredType);
+        var typeDefinition = GetTypeDefinition(desiredType);
         var idExpression = Expression.MakeMemberAccess(checkedExpression, s_idProperty.PropertyInfo);
         var classIDExpression = Expression.MakeMemberAccess(idExpression, s_classIDProperty.PropertyInfo);
-        var allClassDefinitions = EnumerableUtility.Singleton(classDefinition).Concat(classDefinition.GetAllDerivedClasses().Select(cd => cd));
-        var allClassIDExpressions = allClassDefinitions.Select(cd => new SqlLiteralExpression(cd.ID));
 
-        return new SqlInExpression(classIDExpression, new SqlCollectionExpression(typeof(string[]), allClassIDExpressions.Cast<Expression>()));
+        var allClassIDExpressions = new List<Expression>();
+        InlineTypeDefinitionWalker.WalkDescendants(
+            typeDefinition,
+            classDefinition => allClassIDExpressions.Add(new SqlLiteralExpression(classDefinition.ID)),
+            interfaceDefinition => throw new NotImplementedException("Interfaces are not supported")); // TODO R2I Mapping: Add support for interfaces
+
+        return new SqlInExpression(classIDExpression, new SqlCollectionExpression(typeof(string[]), allClassIDExpressions));
       }
       else
       {
@@ -198,12 +204,12 @@ public Expression ResolveTypeCheck (Expression checkedExpression, Type desiredTy
       return _storageSpecificExpressionResolver.ResolveIDPropertyViaForeignKey(entityRefMemberExpression.OriginatingEntity, foreignKeyEndPoint);
     }
 
-    private ClassDefinition GetClassDefinition (Type type)
+    private TypeDefinition GetTypeDefinition (Type type)
     {
-      var classDefinition = MappingConfiguration.Current.GetTypeDefinition(
+      var typeDefinition = MappingConfiguration.Current.GetTypeDefinition(
           type,
           t => new UnmappedItemException(string.Format("The type '{0}' does not identify a queryable table.", t)));
-      return classDefinition;
+      return typeDefinition;
     }
 
     private static PropertyInfoAdapter GetMemberAsProperty (SqlEntityExpression originatingEntity, MemberInfo memberInfo)
@@ -220,10 +226,10 @@ private static PropertyInfoAdapter GetMemberAsProperty (SqlEntityExpression orig
       return PropertyInfoAdapter.Create(property);
     }
 
-    private Expression? ResolveMemberInClassDefinition (
-        SqlEntityExpression originatingEntity, PropertyInfoAdapter propertyInfoAdapter, ClassDefinition classDefinition)
+    private Expression? ResolveMemberInTypeDefinition (
+        SqlEntityExpression originatingEntity, PropertyInfoAdapter propertyInfoAdapter, TypeDefinition typeDefinition)
     {
-      var endPointDefinition = classDefinition.ResolveRelationEndPoint(propertyInfoAdapter);
+      var endPointDefinition = typeDefinition.ResolveRelationEndPoint(propertyInfoAdapter);
       if (endPointDefinition != null)
       {
         if (endPointDefinition.Cardinality != CardinalityType.One)
@@ -235,7 +241,7 @@ private static PropertyInfoAdapter GetMemberAsProperty (SqlEntityExpression orig
         return new SqlEntityRefMemberExpression(originatingEntity, propertyInfoAdapter.PropertyInfo);
       }
 
-      var propertyDefinition = classDefinition.ResolveProperty(propertyInfoAdapter);
+      var propertyDefinition = typeDefinition.ResolveProperty(propertyInfoAdapter);
       if (propertyDefinition != null)
         return _storageSpecificExpressionResolver.ResolveProperty(originatingEntity, propertyDefinition);
 
@@ -245,12 +251,13 @@ private static PropertyInfoAdapter GetMemberAsProperty (SqlEntityExpression orig
     private IRelationEndPointDefinition GetEndPointDefinition (SqlEntityExpression originatingEntity, MemberInfo memberInfo)
     {
       var property = GetMemberAsProperty(originatingEntity, memberInfo);
-      var entityClassDefinition = GetClassDefinition(originatingEntity.Type);
+      var entityTypeDefinition = GetTypeDefinition(originatingEntity.Type);
 
-      var allClassDefinitions = new[] { entityClassDefinition }.Concat(entityClassDefinition.GetAllDerivedClasses());
-      var leftEndPointDefinition = allClassDefinitions
-          .Select(cd => cd.ResolveRelationEndPoint(property))
-          .FirstOrDefault(e => e != null);
+      var leftEndPointDefinition = InlineTypeDefinitionWalker.WalkDescendants(
+          entityTypeDefinition,
+          classDefinition => classDefinition.ResolveRelationEndPoint(property),
+          interfaceDefinition => throw new NotImplementedException("Interfaces are not supported"),
+          match: relationEndPoint => relationEndPoint != null); // TODO R2I Mapping: Add support for interfaces
 
       if (leftEndPointDefinition == null)
       {
diff --git a/Remotion/Data/DomainObjects/Linq/StorageSpecificExpressionResolver.cs b/Remotion/Data/DomainObjects/Linq/StorageSpecificExpressionResolver.cs
index 86490cda53..af43ffc6f2 100644
--- a/Remotion/Data/DomainObjects/Linq/StorageSpecificExpressionResolver.cs
+++ b/Remotion/Data/DomainObjects/Linq/StorageSpecificExpressionResolver.cs
@@ -54,12 +54,12 @@ public IRdbmsPersistenceModelProvider RdbmsPersistenceModelProvider
       get { return _rdbmsPersistenceModelProvider; }
     }
 
-    public SqlEntityDefinitionExpression ResolveEntity (ClassDefinition classDefinition, string tableAlias)
+    public SqlEntityDefinitionExpression ResolveEntity (TypeDefinition typeDefinition, string tableAlias)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNullOrEmpty("tableAlias", tableAlias);
 
-      var entityDefinition = _rdbmsPersistenceModelProvider.GetEntityDefinition(classDefinition);
+      var entityDefinition = _rdbmsPersistenceModelProvider.GetEntityDefinition(typeDefinition);
       var idColumnDefinition = GetSingleColumnForLookup(entityDefinition.ObjectIDProperty);
 
       var tableColumns = (from storageProperty in entityDefinition.GetAllProperties()
@@ -68,7 +68,7 @@ select sqlColumnDefinition
                          ).ToArray();
 
       return new SqlEntityDefinitionExpression(
-          classDefinition.ClassType,
+          typeDefinition.Type,
           tableAlias,
           null,
           e => GetColumnFromEntity(idColumnDefinition, e),
@@ -84,31 +84,31 @@ public Expression ResolveProperty (SqlEntityExpression originatingEntity, Proper
       return ResolveStorageProperty(originatingEntity, storagePropertyDefinition);
     }
 
-    public Expression ResolveIDProperty (SqlEntityExpression originatingEntity, ClassDefinition classDefinition)
+    public Expression ResolveIDProperty (SqlEntityExpression originatingEntity, TypeDefinition typeDefinition)
     {
       ArgumentUtility.CheckNotNull("originatingEntity", originatingEntity);
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      var entityDefinition = _rdbmsPersistenceModelProvider.GetEntityDefinition(classDefinition);
+      var entityDefinition = _rdbmsPersistenceModelProvider.GetEntityDefinition(typeDefinition);
       var valueExpression = ResolveStorageProperty(originatingEntity, entityDefinition.ObjectIDProperty.ValueProperty);
       var classIDExpression = ResolveStorageProperty(originatingEntity, entityDefinition.ObjectIDProperty.ClassIDProperty);
 
       return CreateCompoundObjectIDExpression(classIDExpression, valueExpression);
     }
 
-    public IResolvedTableInfo ResolveTable (ClassDefinition classDefinition, string tableAlias)
+    public IResolvedTableInfo ResolveTable (TypeDefinition typeDefinition, string tableAlias)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNullOrEmpty("tableAlias", tableAlias);
 
       var viewName = InlineRdbmsStorageEntityDefinitionVisitor.Visit<string>(
-          _rdbmsPersistenceModelProvider.GetEntityDefinition(classDefinition),
+          _rdbmsPersistenceModelProvider.GetEntityDefinition(typeDefinition),
           (table, continuation) => GetFullyQualifiedEntityName(table.ViewName),
           (filterView, continuation) => GetFullyQualifiedEntityName(filterView.ViewName),
           (unionView, continuation) => GetFullyQualifiedEntityName(unionView.ViewName),
           (emptyView, continuation) => GetFullyQualifiedEntityName(emptyView.ViewName));
 
-      return new ResolvedSimpleTableInfo(classDefinition.ClassType, viewName, tableAlias);
+      return new ResolvedSimpleTableInfo(typeDefinition.Type, viewName, tableAlias);
     }
 
     public ResolvedJoinInfo ResolveJoin (
@@ -120,8 +120,8 @@ public ResolvedJoinInfo ResolveJoin (
 
       var leftKey = GetJoinColumn(leftEndPoint, originatingEntity);
 
-      var resolvedSimpleTableInfo = ResolveTable(rightEndPoint.ClassDefinition, tableAlias);
-      var rightEntity = ResolveEntity(rightEndPoint.ClassDefinition, tableAlias);
+      var resolvedSimpleTableInfo = ResolveTable(rightEndPoint.TypeDefinition, tableAlias);
+      var rightEntity = ResolveEntity(rightEndPoint.TypeDefinition, tableAlias);
 
       Expression rightKey = GetJoinColumn(rightEndPoint, rightEntity);
 
diff --git a/Remotion/Data/DomainObjects/Mapping/AnonymousRelationEndPointDefinition.cs b/Remotion/Data/DomainObjects/Mapping/AnonymousRelationEndPointDefinition.cs
index 5999c23139..f525edfcc4 100644
--- a/Remotion/Data/DomainObjects/Mapping/AnonymousRelationEndPointDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/AnonymousRelationEndPointDefinition.cs
@@ -28,12 +28,12 @@ namespace Remotion.Data.DomainObjects.Mapping
   public class AnonymousRelationEndPointDefinition : IRelationEndPointDefinition, IRelationEndPointDefinitionSetter
   {
     private RelationDefinition? _relationDefinition;
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
 
-    public AnonymousRelationEndPointDefinition (ClassDefinition classDefinition)
+    public AnonymousRelationEndPointDefinition (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
-      _classDefinition = classDefinition;
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
+      _typeDefinition = typeDefinition;
     }
 
     public RelationDefinition RelationDefinition
@@ -45,9 +45,9 @@ public RelationDefinition RelationDefinition
       }
     }
 
-    public ClassDefinition ClassDefinition
+    public TypeDefinition TypeDefinition
     {
-      get { return _classDefinition; }
+      get { return _typeDefinition; }
     }
 
     public string? PropertyName
diff --git a/Remotion/Data/DomainObjects/Mapping/ClassDefinition.cs b/Remotion/Data/DomainObjects/Mapping/ClassDefinition.cs
index 0c1e6029bb..b49380250c 100644
--- a/Remotion/Data/DomainObjects/Mapping/ClassDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/ClassDefinition.cs
@@ -18,89 +18,68 @@
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
 using System.Threading;
 using Remotion.Data.DomainObjects.Infrastructure;
-using Remotion.Data.DomainObjects.Persistence.Model;
 using Remotion.Reflection;
 using Remotion.Utilities;
 
 namespace Remotion.Data.DomainObjects.Mapping
 {
-  [DebuggerDisplay("{GetType().Name} for {ClassType.GetFullNameSafe()}")]
-  public class ClassDefinition
+  [DebuggerDisplay("{GetType().Name} for {Type.Name}")]
+  public class ClassDefinition : TypeDefinition
   {
-    private readonly string _id;
-    private bool _isReadOnly;
-    private readonly Type? _storageGroupType;
-    private readonly DefaultStorageClass _defaultStorageClass;
-    private readonly PropertyAccessorDataCache _propertyAccessorDataCache;
-    private readonly DoubleCheckedLockingContainer<RelationEndPointDefinitionCollection> _cachedRelationEndPointDefinitions;
-    private readonly DoubleCheckedLockingContainer<PropertyDefinitionCollection> _cachedPropertyDefinitions;
-    private readonly ClassDefinition? _baseClass;
-    private PropertyDefinitionCollection? _propertyDefinitions;
-    private RelationEndPointDefinitionCollection? _relationEndPoints;
-    private IStorageEntityDefinition? _storageEntityDefinition;
-    private ReadOnlyCollection<ClassDefinition>? _derivedClasses;
-    private readonly bool _isAbstract;
-    private readonly Type _classType;
-    private readonly IPersistentMixinFinder _persistentMixinFinder;
-    private readonly IDomainObjectCreator _instanceCreator;
     private readonly Lazy<Func<ObjectID, IDomainObjectHandle<DomainObject>>> _handleCreator;
 
+    private ReadOnlyCollection<ClassDefinition>? _derivedClasses;
+
+    public string ID { get; }
+
+    public bool IsAbstract { get; }
+
+    public IDomainObjectCreator InstanceCreator { get; }
+
+    public ClassDefinition? BaseClass { get; }
+
+    public ReadOnlyCollection<InterfaceDefinition> ImplementedInterfaces { get; }
+
+    public IPersistentMixinFinder PersistentMixinFinder { get; }
+
     public ClassDefinition (
         string id,
-        Type classType,
+        Type type,
         bool isAbstract,
         ClassDefinition? baseClass,
+        IEnumerable<InterfaceDefinition> implementedInterfaces,
         Type? storageGroupType,
         DefaultStorageClass defaultStorageClass,
         IPersistentMixinFinder persistentMixinFinder,
         IDomainObjectCreator instanceCreator)
+        : base(type, storageGroupType, defaultStorageClass)
     {
       ArgumentUtility.CheckNotNullOrEmpty("id", id);
-      ArgumentUtility.CheckNotNull("classType", classType);
       ArgumentUtility.CheckNotNull("persistentMixinFinder", persistentMixinFinder);
 
-      _id = id;
-      _storageGroupType = storageGroupType;
-      _defaultStorageClass = defaultStorageClass;
+      var implementedInterfacesReadOnly = implementedInterfaces.ToList().AsReadOnly();
+      ArgumentUtility.CheckNotNullOrItemsNull(nameof(implementedInterfaces), implementedInterfacesReadOnly);
 
-      _classType = classType;
-      _persistentMixinFinder = persistentMixinFinder;
-      _isAbstract = isAbstract;
+      ID = id;
 
-      _propertyAccessorDataCache = new PropertyAccessorDataCache(this);
-      _cachedRelationEndPointDefinitions = new DoubleCheckedLockingContainer<RelationEndPointDefinitionCollection>(
-           () => RelationEndPointDefinitionCollection.CreateForAllRelationEndPoints(this, true));
-      _cachedPropertyDefinitions =
-          new DoubleCheckedLockingContainer<PropertyDefinitionCollection>(
-              () => new PropertyDefinitionCollection(PropertyDefinitionCollection.CreateForAllProperties(this, true), true));
+      PersistentMixinFinder = persistentMixinFinder;
+      IsAbstract = isAbstract;
 
-      _baseClass = baseClass;
-      _instanceCreator = instanceCreator;
+      BaseClass = baseClass;
+      ImplementedInterfaces = implementedInterfacesReadOnly;
+
+      InstanceCreator = instanceCreator;
       _handleCreator = new Lazy<Func<ObjectID, IDomainObjectHandle<DomainObject>>>(BuildHandleCreator, LazyThreadSafetyMode.PublicationOnly);
     }
 
     // methods and properties
 
-    public PropertyAccessorDataCache PropertyAccessorDataCache
-    {
-      get { return _propertyAccessorDataCache; }
-    }
-
-    public bool IsReadOnly
-    {
-      get { return _isReadOnly; }
-    }
-
-    public void SetReadOnly ()
-    {
-      _isReadOnly = true;
-    }
-
     public bool IsSameOrBaseClassOf (ClassDefinition classDefinition)
     {
       ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
@@ -120,63 +99,26 @@ public bool IsSameOrBaseClassOf (ClassDefinition classDefinition)
       return false;
     }
 
-    public ClassDefinition[] GetAllDerivedClasses ()
-    {
-      var allDerivedClasses = new List<ClassDefinition>();
-      FillAllDerivedClasses(allDerivedClasses);
-      return allDerivedClasses.ToArray();
-    }
-
-    public ClassDefinition GetInheritanceRootClass ()
+    public override bool IsAssignableFrom (TypeDefinition other)
     {
-      if (BaseClass != null)
-        return BaseClass.GetInheritanceRootClass();
-
-      return this;
-    }
-
-    [Obsolete(
-        "Contains (...) method was ambiguous between GetPropertyDefinitions() and MyPropertyDefinitions. Use GetPropertyDefinitions().Contains (...) instead. (Version: 3.0.0)",
-        true)]
-    public bool Contains (PropertyDefinition propertyDefinition)
-    {
-      throw new NotSupportedException("Use GetPropertyDefinitions().Contains (...) instead. (Version: 3.0.0)");
-    }
-
-    public PropertyDefinitionCollection GetPropertyDefinitions ()
-    {
-      return _cachedPropertyDefinitions.Value;
-    }
-
-    public RelationEndPointDefinitionCollection GetRelationEndPointDefinitions ()
-    {
-      return _cachedRelationEndPointDefinitions.Value;
-    }
-
-    public IRelationEndPointDefinition? GetRelationEndPointDefinition (string propertyName)
-    {
-      ArgumentUtility.CheckNotNullOrEmpty("propertyName", propertyName);
+      if (ReferenceEquals(this, other))
+        return true;
 
-      return _cachedRelationEndPointDefinitions.Value[propertyName];
+      return DerivedClasses.Any(e => e.IsAssignableFrom(other));
     }
 
-    public IRelationEndPointDefinition GetMandatoryRelationEndPointDefinition (string propertyName)
+    public ClassDefinition[] GetAllDerivedClasses ()
     {
-      ArgumentUtility.CheckNotNullOrEmpty("propertyName", propertyName);
-
-      IRelationEndPointDefinition? relationEndPointDefinition = GetRelationEndPointDefinition(propertyName);
-
-      if (relationEndPointDefinition == null)
-        throw CreateMappingException("No relation found for class '{0}' and property '{1}'.", ID, propertyName);
-
-      return relationEndPointDefinition;
+      var allDerivedClasses = new List<ClassDefinition>();
+      FillAllDerivedClasses(allDerivedClasses);
+      return allDerivedClasses.ToArray();
     }
 
     public bool IsMyRelationEndPoint (IRelationEndPointDefinition relationEndPointDefinition)
     {
       ArgumentUtility.CheckNotNull("relationEndPointDefinition", relationEndPointDefinition);
 
-      return (relationEndPointDefinition.ClassDefinition == this && !relationEndPointDefinition.IsAnonymous);
+      return (relationEndPointDefinition.TypeDefinition == this && !relationEndPointDefinition.IsAnonymous);
     }
 
     public bool IsRelationEndPoint (IRelationEndPointDefinition relationEndPointDefinition)
@@ -192,69 +134,23 @@ public bool IsRelationEndPoint (IRelationEndPointDefinition relationEndPointDefi
       return false;
     }
 
-    public PropertyDefinition? GetPropertyDefinition (string propertyName)
+    public override PropertyDefinition? GetPropertyDefinition (string propertyName)
     {
       ArgumentUtility.CheckNotNullOrEmpty("propertyName", propertyName);
 
-      var propertyDefinition = MyPropertyDefinitions[propertyName];
-
+      var propertyDefinition = base.GetPropertyDefinition(propertyName);
       if (propertyDefinition == null && BaseClass != null)
         return BaseClass.GetPropertyDefinition(propertyName);
 
       return propertyDefinition;
     }
 
-    public void SetStorageEntity (IStorageEntityDefinition storageEntityDefinition)
-    {
-      ArgumentUtility.CheckNotNull("storageEntityDefinition", storageEntityDefinition);
-
-      if (_isReadOnly)
-        throw new NotSupportedException(String.Format("Class '{0}' is read-only.", ID));
-
-      _storageEntityDefinition = storageEntityDefinition;
-    }
-
-    public void SetPropertyDefinitions (PropertyDefinitionCollection propertyDefinitions)
-    {
-      ArgumentUtility.CheckNotNull("propertyDefinitions", propertyDefinitions);
-
-      if (_propertyDefinitions != null)
-        throw new InvalidOperationException(String.Format("The property-definitions for class '{0}' have already been set.", ID));
-
-      if (_isReadOnly)
-        throw new NotSupportedException(String.Format("Class '{0}' is read-only.", ID));
-
-      CheckPropertyDefinitions(propertyDefinitions);
-
-      _propertyDefinitions = propertyDefinitions;
-      _propertyDefinitions.SetReadOnly();
-    }
-
-    public void SetRelationEndPointDefinitions (RelationEndPointDefinitionCollection relationEndPoints)
-    {
-      ArgumentUtility.CheckNotNull("relationEndPoints", relationEndPoints);
-
-      if (_relationEndPoints != null)
-        throw new InvalidOperationException(String.Format("The relation end point definitions for class '{0}' have already been set.", ID));
-
-      if (_isReadOnly)
-        throw new NotSupportedException(String.Format("Class '{0}' is read-only.", ID));
-
-      CheckRelationEndPointDefinitions(relationEndPoints);
-
-      _relationEndPoints = relationEndPoints;
-      _relationEndPoints.SetReadOnly();
-    }
-
     public void SetDerivedClasses (IEnumerable<ClassDefinition> derivedClasses)
     {
       ArgumentUtility.CheckNotNull("derivedClasses", derivedClasses);
 
-      if (_derivedClasses != null)
-        throw new InvalidOperationException(String.Format("The derived-classes for class '{0}' have already been set.", ID));
-
-      if (_isReadOnly)
-        throw new NotSupportedException(String.Format("Class '{0}' is read-only.", ID));
+      if (IsReadOnly)
+        throw new NotSupportedException($"Class '{ID}' is read-only.");
 
       var derivedClassesReadOnly = derivedClasses.ToList().AsReadOnly();
       CheckDerivedClass(derivedClassesReadOnly);
@@ -262,147 +158,22 @@ public void SetDerivedClasses (IEnumerable<ClassDefinition> derivedClasses)
       _derivedClasses = derivedClassesReadOnly;
     }
 
-    public PropertyDefinition GetMandatoryPropertyDefinition (string propertyName)
-    {
-      PropertyDefinition? propertyDefinition = GetPropertyDefinition(propertyName);
-
-      if (propertyDefinition == null)
-        throw CreateMappingException("Class '{0}' does not contain the property '{1}'.", ID, propertyName);
-
-      return propertyDefinition;
-    }
-
-    public PropertyDefinition? this [string propertyName]
-    {
-      get
-      {
-        ArgumentUtility.CheckNotNullOrEmpty("propertyName", propertyName);
-        return MyPropertyDefinitions[propertyName];
-      }
-    }
-
-    public string ID
-    {
-      get { return _id; }
-    }
-
-    public IStorageEntityDefinition StorageEntityDefinition
-    {
-      get
-      {
-        Assertion.IsNotNull(_storageEntityDefinition, "StorageEntityDefinition has not been set for class definition '{0}'.", _id);
-        return _storageEntityDefinition;
-      }
-    }
-
-    public bool HasStorageEntityDefinitionBeenSet
-    {
-      get { return _storageEntityDefinition != null; }
-    }
-
-    public Type ClassType
-    {
-      get { return _classType; }
-    }
-
-    public virtual bool IsClassTypeResolved
-    {
-      get { return true; }
-    }
-
-    public bool IsAbstract
-    {
-      get { return _isAbstract; }
-    }
-
-    public IDomainObjectCreator InstanceCreator
-    {
-      get { return _instanceCreator; }
-    }
-
-    public Func<ObjectID, IDomainObjectHandle<DomainObject>> HandleCreator
-    {
-      get { return _handleCreator.Value; }
-    }
-
-    public PropertyDefinition? ResolveProperty (IPropertyInformation propertyInformation)
-    {
-      ArgumentUtility.CheckNotNull("propertyInformation", propertyInformation);
-
-      var propertyAccessorData = PropertyAccessorDataCache.ResolvePropertyAccessorData(propertyInformation);
-      return propertyAccessorData == null ? null : propertyAccessorData.PropertyDefinition;
-    }
-
-    public IRelationEndPointDefinition? ResolveRelationEndPoint (IPropertyInformation propertyInformation)
-    {
-      ArgumentUtility.CheckNotNull("propertyInformation", propertyInformation);
-
-      var propertyAccessorData = PropertyAccessorDataCache.ResolvePropertyAccessorData(propertyInformation);
-      return propertyAccessorData == null ? null : propertyAccessorData.RelationEndPointDefinition;
-    }
-
-    public ClassDefinition? BaseClass
-    {
-      get { return _baseClass; }
-    }
-
-    public Type? StorageGroupType
-    {
-      get { return _storageGroupType; }
-    }
-
-    public DefaultStorageClass DefaultStorageClass
-    {
-      get { return _defaultStorageClass; }
-    }
-
-    public PropertyDefinitionCollection MyPropertyDefinitions
-    {
-      get
-      {
-        if (_propertyDefinitions == null)
-          throw new InvalidOperationException(String.Format("No property definitions have been set for class '{0}'.", ID));
-
-        return _propertyDefinitions;
-      }
-    }
-
-    public RelationEndPointDefinitionCollection MyRelationEndPointDefinitions
-    {
-      get
-      {
-        if (_relationEndPoints == null)
-          throw new InvalidOperationException(String.Format("No relation end point definitions have been set for class '{0}'.", ID));
-
-        return _relationEndPoints;
-      }
-    }
+    public Func<ObjectID, IDomainObjectHandle<DomainObject>> HandleCreator => _handleCreator.Value;
 
     public ReadOnlyCollection<ClassDefinition> DerivedClasses
     {
       get
       {
         if (_derivedClasses == null)
-          throw new InvalidOperationException(String.Format("No derived classes have been set for class '{0}'.", ID));
+          throw new InvalidOperationException($"No derived classes have been set for class '{ID}'.");
 
         return _derivedClasses;
       }
     }
 
-    public bool IsPartOfInheritanceHierarchy
-    {
-      get { return (BaseClass != null || DerivedClasses.Count > 0); }
-    }
-
-    public IPersistentMixinFinder PersistentMixinFinder
-    {
-      get { return _persistentMixinFinder; }
-    }
+    public override bool IsPartOfInheritanceHierarchy => BaseClass != null || DerivedClasses.Count > 0;
 
-    public IEnumerable<Type> PersistentMixins
-    {
-      get { return _persistentMixinFinder.GetPersistentMixins(); }
-    }
+    public IEnumerable<Type> PersistentMixins => PersistentMixinFinder.GetPersistentMixins();
 
     public Type? GetPersistentMixin (Type mixinToSearch)
     {
@@ -415,30 +186,20 @@ public IEnumerable<Type> PersistentMixins
 
     public void ValidateCurrentMixinConfiguration ()
     {
-      var currentMixinConfiguration = Mapping.PersistentMixinFinder.GetMixinConfigurationForDomainObjectType(ClassType);
+      var currentMixinConfiguration = Mapping.PersistentMixinFinder.GetMixinConfigurationForDomainObjectType(Type);
       if (!Equals(currentMixinConfiguration, PersistentMixinFinder.MixinConfiguration))
       {
-        string message = String.Format(
+        string message = string.Format(
             "The mixin configuration for domain object type '{0}' was changed after the mapping information was built." + Environment.NewLine
             + "Original configuration: {1}." + Environment.NewLine
             + "Active configuration: {2}",
-            ClassType,
+            Type,
             PersistentMixinFinder.MixinConfiguration,
             currentMixinConfiguration);
         throw new MappingException(message);
       }
     }
 
-    public override string ToString ()
-    {
-      return GetType().GetFullNameChecked() + ": " + _id;
-    }
-
-    private MappingException CreateMappingException (string message, params object?[] args)
-    {
-      return new MappingException(String.Format(message, args));
-    }
-
     private void FillAllDerivedClasses (List<ClassDefinition> allDerivedClasses)
     {
       foreach (ClassDefinition derivedClass in DerivedClasses)
@@ -448,61 +209,76 @@ private void FillAllDerivedClasses (List<ClassDefinition> allDerivedClasses)
       }
     }
 
-    private void CheckPropertyDefinitions (IEnumerable<PropertyDefinition> propertyDefinitions)
+    public override void Accept (ITypeDefinitionVisitor visitor)
+    {
+      ArgumentUtility.CheckNotNull("visitor", visitor);
+
+      visitor.VisitClassDefinition(this);
+    }
+
+    [return: MaybeNull]
+    public override T Accept<T> (ITypeDefinitionVisitor<T> visitor)
+    {
+      ArgumentUtility.CheckNotNull("visitor", visitor);
+
+      return visitor.VisitClassDefinition(this);
+    }
+
+    public override void SetReadOnly ()
+    {
+      if (_derivedClasses == null)
+        throw new InvalidOperationException("Cannot set the type definition read-only as the derived classes are not set.");
+
+      base.SetReadOnly();
+    }
+
+    public override string ToString () => $"{GetType().Name}: {ID}";
+
+    protected override void CheckPropertyDefinitions (IEnumerable<PropertyDefinition> propertyDefinitions)
     {
       foreach (var propertyDefinition in propertyDefinitions)
       {
-        if (!ReferenceEquals(propertyDefinition.ClassDefinition, this))
+        if (!ReferenceEquals(propertyDefinition.TypeDefinition, this))
         {
-          throw CreateMappingException(
-              "Property '{0}' cannot be added to class '{1}', because it was initialized for class '{2}'.",
-              propertyDefinition.PropertyName,
-              _id,
-              propertyDefinition.ClassDefinition.ID);
+          throw new MappingException(
+              $"Property '{propertyDefinition.PropertyName}' cannot be added to class '{ID}',"
+              + $" because it was initialized for type '{propertyDefinition.TypeDefinition.Type.GetFullNameSafe()}'.");
         }
 
-        var basePropertyDefinition = BaseClass != null ? BaseClass.GetPropertyDefinition(propertyDefinition.PropertyName) : null;
-        if (basePropertyDefinition != null)
+        var baseClass = BaseClass;
+        var basePropertyDefinition = baseClass?.GetPropertyDefinition(propertyDefinition.PropertyName);
+        if (baseClass != null && basePropertyDefinition != null)
         {
-          string definingClass = String.Format("base class '{0}'", basePropertyDefinition.ClassDefinition.ID);
-
-          throw CreateMappingException(
-              "Property '{0}' cannot be added to class '{1}', because {2} already defines a property with the same name.",
-              propertyDefinition.PropertyName,
-              _id,
-              definingClass);
+          throw new MappingException(
+              $"Property '{propertyDefinition.PropertyName}' cannot be added to class '{ID}',"
+              + $" because base type '{basePropertyDefinition.TypeDefinition.Type.GetFullNameSafe()}' already defines a property with the same name.");
         }
       }
     }
 
-    private void CheckRelationEndPointDefinitions (IEnumerable<IRelationEndPointDefinition> relationEndPoints)
+    protected override void CheckRelationEndPointDefinitions (IEnumerable<IRelationEndPointDefinition> relationEndPoints)
     {
       foreach (IRelationEndPointDefinition endPointDefinition in relationEndPoints)
       {
-        var relationEndPointClassDefinition = endPointDefinition.ClassDefinition;
+        var relationEndPointClassDefinition = endPointDefinition.TypeDefinition;
         var relationEndPointPropertyName = endPointDefinition.PropertyName;
         Assertion.DebugAssert(endPointDefinition.IsAnonymous == false, "endPointDefinition.IsAnonymous == false");
         Assertion.DebugIsNotNull(relationEndPointPropertyName, "endPointDefinition.PropertyName != null when endPointDefinition.IsAnonymous == false");
 
         if (!ReferenceEquals(relationEndPointClassDefinition, this))
         {
-          throw CreateMappingException(
-              "Relation end point for property '{0}' cannot be added to class '{1}', because it was initialized for class '{2}'.",
-              relationEndPointPropertyName,
-              _id,
-              relationEndPointClassDefinition.ID);
+          throw new MappingException(
+              $"Relation end point for property '{relationEndPointPropertyName}' cannot be added to class '{ID}',"
+              + $" because it was initialized for class '{relationEndPointClassDefinition.Type.GetFullNameSafe()}'.");
         }
 
-        var baseEndPointDefinition = BaseClass != null ? BaseClass.GetRelationEndPointDefinition(relationEndPointPropertyName) : null;
-        if (baseEndPointDefinition != null)
+        var baseClass = BaseClass;
+        var baseEndPointDefinition = baseClass?.GetRelationEndPointDefinition(relationEndPointPropertyName);
+        if (baseClass != null && baseEndPointDefinition != null)
         {
-          string definingClass = String.Format("base class '{0}'", baseEndPointDefinition.ClassDefinition.ID);
-
-          throw CreateMappingException(
-              "Relation end point for property '{0}' cannot be added to class '{1}', because {2} already defines a relation end point with the same property name.",
-              relationEndPointPropertyName,
-              _id,
-              definingClass);
+          throw new MappingException(
+              $"Relation end point for property '{relationEndPointPropertyName}' cannot be added to class '{ID}',"
+              + $" because base class '{baseClass.ID}' already defines a relation end point with the same property name.");
         }
       }
     }
@@ -513,17 +289,14 @@ private void CheckDerivedClass (IEnumerable<ClassDefinition> derivedClasses)
       {
         if (derivedClass.BaseClass == null)
         {
-          throw CreateMappingException(
-              "Derived class '{0}' cannot be added to class '{1}', because it has no base class definition defined.", derivedClass.ID, _id);
+          throw new MappingException(
+              $"Derived class '{derivedClass.ID}' cannot be added to class '{ID}', because it has no base class definition defined.");
         }
 
         if (derivedClass.BaseClass != this)
         {
-          throw CreateMappingException(
-              "Derived class '{0}' cannot be added to class '{1}', because it has class '{2}' as its base class definition defined.",
-              derivedClass.ID,
-              _id,
-              derivedClass.BaseClass.ID);
+          throw new MappingException(
+              $"Derived class '{derivedClass.ID}' cannot be added to class '{ID}', because it has class '{derivedClass.BaseClass.ID}' as its base class definition defined.");
         }
       }
     }
@@ -533,12 +306,11 @@ private Func<ObjectID, IDomainObjectHandle<DomainObject>> BuildHandleCreator ()
       var objectIDParameter = Expression.Parameter(typeof(ObjectID), "objectID");
 
       Expression body;
-      if (typeof(DomainObject).IsAssignableFrom(ClassType))
+      if (typeof(DomainObject).IsAssignableFrom(Type))
       {
-        var handleType = typeof(DomainObjectHandle<>).MakeGenericType(ClassType);
+        var handleType = typeof(DomainObjectHandle<>).MakeGenericType(Type);
 
-        var constructorInfo = handleType.GetConstructor(
-            BindingFlags.Public | BindingFlags.Instance, null, new[] { typeof(ObjectID) }, null);
+        var constructorInfo = handleType.GetConstructor(BindingFlags.Public | BindingFlags.Instance, null, new[] { typeof(ObjectID) }, null);
         Assertion.DebugAssert(constructorInfo != null);
 
         body = Expression.New(constructorInfo, objectIDParameter);
@@ -548,7 +320,7 @@ private Func<ObjectID, IDomainObjectHandle<DomainObject>> BuildHandleCreator ()
         var throwingDelegate =
             (Func<IDomainObjectHandle<DomainObject>>)(() =>
             {
-              throw new InvalidOperationException("Handles cannot be created when the ClassType does not derive from DomainObject.");
+              throw new InvalidOperationException("Handles cannot be created when the Type does not derive from DomainObject.");
             });
         body = Expression.Invoke(Expression.Constant(throwingDelegate));
       }
diff --git a/Remotion/Data/DomainObjects/Mapping/ClassDefinitionCollectionFactory.cs b/Remotion/Data/DomainObjects/Mapping/ClassDefinitionCollectionFactory.cs
index 56945c278f..283d3e44c3 100644
--- a/Remotion/Data/DomainObjects/Mapping/ClassDefinitionCollectionFactory.cs
+++ b/Remotion/Data/DomainObjects/Mapping/ClassDefinitionCollectionFactory.cs
@@ -50,20 +50,20 @@ public ClassDefinition[] CreateClassDefinitionCollection (IEnumerable<Type> type
 
       SetDerivedClasses(classDefinitions.Values);
 
-      return classDefinitions.Values.ToArray();
+      return classDefinitions.Values.ToArray(); // TODO R2I Create InterfaceCollection
     }
 
-    public ClassDefinition GetClassDefinition (IDictionary<Type, ClassDefinition> classDefinitions, Type classType)
+    public ClassDefinition GetClassDefinition (IDictionary<Type, ClassDefinition> classDefinitions, Type type)
     {
       ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
-      ArgumentUtility.CheckNotNull("classType", classType);
+      ArgumentUtility.CheckNotNull("type", type);
 
-      if (classDefinitions.ContainsKey(classType))
-        return classDefinitions[classType];
+      if (classDefinitions.ContainsKey(type))
+        return classDefinitions[type];
 
-      var baseClassDefinition = GetBaseClassDefinition(classDefinitions, classType);
-      var classDefinition = _mappingObjectFactory.CreateClassDefinition(classType, baseClassDefinition);
-      classDefinitions.Add(classDefinition.ClassType, classDefinition);
+      var baseClassDefinition = GetBaseClassDefinition(classDefinitions, type);
+      var classDefinition = _mappingObjectFactory.CreateClassDefinition(type, baseClassDefinition);
+      classDefinitions.Add(classDefinition.Type, classDefinition);
 
       return classDefinition;
     }
diff --git a/Remotion/Data/DomainObjects/Mapping/DomainObjectCollectionRelationEndPointDefinition.cs b/Remotion/Data/DomainObjects/Mapping/DomainObjectCollectionRelationEndPointDefinition.cs
index bd00d49a4f..00207ac47c 100644
--- a/Remotion/Data/DomainObjects/Mapping/DomainObjectCollectionRelationEndPointDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/DomainObjectCollectionRelationEndPointDefinition.cs
@@ -31,24 +31,24 @@ public class DomainObjectCollectionRelationEndPointDefinition : IRelationEndPoin
   {
     private readonly string _propertyName;
     private RelationDefinition? _relationDefinition;
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
     private readonly bool _isMandatory;
     private readonly Lazy<SortExpressionDefinition?> _sortExpression;
     private readonly IPropertyInformation _propertyInfo;
 
     public DomainObjectCollectionRelationEndPointDefinition (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         bool isMandatory,
         Lazy<SortExpressionDefinition?> sortExpression,
         IPropertyInformation propertyInfo)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNullOrEmpty("propertyName", propertyName);
       ArgumentUtility.CheckNotNull("sortExpression", sortExpression);
       ArgumentUtility.CheckNotNull("propertyInfo", propertyInfo);
 
-      _classDefinition = classDefinition;
+      _typeDefinition = typeDefinition;
       _isMandatory = isMandatory;
       _propertyName = propertyName;
       _sortExpression = sortExpression;
@@ -75,9 +75,9 @@ public RelationDefinition RelationDefinition
       }
     }
 
-    public ClassDefinition ClassDefinition
+    public TypeDefinition TypeDefinition
     {
-      get { return _classDefinition; }
+      get { return _typeDefinition; }
     }
 
     public bool IsMandatory
diff --git a/Remotion/Data/DomainObjects/Mapping/IMappingConfiguration.cs b/Remotion/Data/DomainObjects/Mapping/IMappingConfiguration.cs
index 79b6974fa8..bb85e96900 100644
--- a/Remotion/Data/DomainObjects/Mapping/IMappingConfiguration.cs
+++ b/Remotion/Data/DomainObjects/Mapping/IMappingConfiguration.cs
@@ -24,12 +24,10 @@ namespace Remotion.Data.DomainObjects.Mapping
   /// </summary>
   public interface IMappingConfiguration
   {
-    ClassDefinition[] GetTypeDefinitions ();
-    bool ContainsTypeDefinition (Type classType);
-    ClassDefinition GetTypeDefinition (Type classType);
-    ClassDefinition GetTypeDefinition (Type classType, Func<Type, Exception> missingTypeDefinitionExceptionFactory);
+    TypeDefinition[] GetTypeDefinitions ();
+    bool ContainsTypeDefinition (Type type);
+    TypeDefinition GetTypeDefinition (Type type, Func<Type, Exception> missingTypeDefinitionExceptionFactory);
     bool ContainsClassDefinition (string classID);
-    ClassDefinition GetClassDefinition (string classID);
     ClassDefinition GetClassDefinition (string classID, Func<string, Exception> missingClassDefinitionExceptionFactory);
 
     bool ResolveTypes { get; }
diff --git a/Remotion/Data/DomainObjects/Mapping/IMappingObjectFactory.cs b/Remotion/Data/DomainObjects/Mapping/IMappingObjectFactory.cs
index 860b82eeb8..30cf0c65b9 100644
--- a/Remotion/Data/DomainObjects/Mapping/IMappingObjectFactory.cs
+++ b/Remotion/Data/DomainObjects/Mapping/IMappingObjectFactory.cs
@@ -27,18 +27,18 @@ public interface IMappingObjectFactory
   {
     ClassDefinition CreateClassDefinition (Type type, ClassDefinition? baseClass);
 
-    PropertyDefinition CreatePropertyDefinition (ClassDefinition classDefinition, IPropertyInformation propertyInfo);
+    PropertyDefinition CreatePropertyDefinition (TypeDefinition typeDefinition, IPropertyInformation propertyInfo);
 
     RelationDefinition CreateRelationDefinition (
-        IDictionary<Type, ClassDefinition> classDefinitions, ClassDefinition classDefinition, IPropertyInformation propertyInfo);
+        IDictionary<Type, TypeDefinition> typeDefinitions, TypeDefinition typeDefinition, IPropertyInformation propertyInfo);
 
-    IRelationEndPointDefinition CreateRelationEndPointDefinition (ClassDefinition classDefinition, IPropertyInformation propertyInfo);
+    IRelationEndPointDefinition CreateRelationEndPointDefinition (TypeDefinition typeDefinition, IPropertyInformation propertyInfo);
 
-    ClassDefinition[] CreateClassDefinitionCollection (IEnumerable<Type> types);
+    TypeDefinition[] CreateTypeDefinitionCollection (IEnumerable<Type> types);
 
-    PropertyDefinitionCollection CreatePropertyDefinitionCollection (ClassDefinition classDefinition, IEnumerable<IPropertyInformation> propertyInfos);
+    PropertyDefinitionCollection CreatePropertyDefinitionCollection (TypeDefinition typeDefinition, IEnumerable<IPropertyInformation> propertyInfos);
 
-    RelationDefinition[] CreateRelationDefinitionCollection (IDictionary<Type, ClassDefinition> classDefinitions);
-    RelationEndPointDefinitionCollection CreateRelationEndPointDefinitionCollection (ClassDefinition classDefinition);
+    RelationDefinition[] CreateRelationDefinitionCollection (IDictionary<Type, TypeDefinition> typeDefinitions);
+    RelationEndPointDefinitionCollection CreateRelationEndPointDefinitionCollection (TypeDefinition typeDefinition);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/IRelationEndPointDefinition.cs b/Remotion/Data/DomainObjects/Mapping/IRelationEndPointDefinition.cs
index 1d509b8e98..f014572462 100644
--- a/Remotion/Data/DomainObjects/Mapping/IRelationEndPointDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/IRelationEndPointDefinition.cs
@@ -23,7 +23,7 @@ namespace Remotion.Data.DomainObjects.Mapping
 public interface IRelationEndPointDefinition
 {
   RelationDefinition RelationDefinition { get; }
-  ClassDefinition ClassDefinition { get; }
+  TypeDefinition TypeDefinition { get; }
   string? PropertyName { get; }
   IPropertyInformation? PropertyInfo { get; }
   bool IsMandatory { get; }
diff --git a/Remotion/Data/DomainObjects/Mapping/ITypeDefinitionVisitor.cs b/Remotion/Data/DomainObjects/Mapping/ITypeDefinitionVisitor.cs
new file mode 100644
index 0000000000..02ea604ba1
--- /dev/null
+++ b/Remotion/Data/DomainObjects/Mapping/ITypeDefinitionVisitor.cs
@@ -0,0 +1,28 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+namespace Remotion.Data.DomainObjects.Mapping
+{
+  /// <summary>
+  /// Provides a method to dispatch on <see cref="TypeDefinition"/> implementations.
+  /// </summary>
+  public interface ITypeDefinitionVisitor
+  {
+    void VisitClassDefinition (ClassDefinition classDefinition);
+
+    void VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition);
+  }
+}
diff --git a/Remotion/Data/DomainObjects/Mapping/ITypeDefinitionVisitor1.cs b/Remotion/Data/DomainObjects/Mapping/ITypeDefinitionVisitor1.cs
new file mode 100644
index 0000000000..7cd34f8f38
--- /dev/null
+++ b/Remotion/Data/DomainObjects/Mapping/ITypeDefinitionVisitor1.cs
@@ -0,0 +1,28 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+namespace Remotion.Data.DomainObjects.Mapping
+{
+  /// <summary>
+  /// Provides a method to dispatch on <see cref="TypeDefinition"/> implementations returning a result of <typeparamref name="T"/>.
+  /// </summary>
+  public interface ITypeDefinitionVisitor<out T>
+  {
+    T? VisitClassDefinition (ClassDefinition classDefinition);
+
+    T? VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition);
+  }
+}
diff --git a/Remotion/Data/DomainObjects/Mapping/InlineTypeDefinitionVisitor.cs b/Remotion/Data/DomainObjects/Mapping/InlineTypeDefinitionVisitor.cs
new file mode 100644
index 0000000000..56407e59b5
--- /dev/null
+++ b/Remotion/Data/DomainObjects/Mapping/InlineTypeDefinitionVisitor.cs
@@ -0,0 +1,112 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using Remotion.Utilities;
+
+namespace Remotion.Data.DomainObjects.Mapping
+{
+  /// <summary>
+  /// Visits the given <see cref="TypeDefinition"/> and executes a handler based on the entity's type.
+  /// </summary>
+  public static class InlineTypeDefinitionVisitor
+  {
+    private class TypeDefinitionVisitor<T> : ITypeDefinitionVisitor<T>
+    {
+      private readonly Func<ClassDefinition, T?> _classDefinitionHandler;
+      private readonly Func<InterfaceDefinition, T?> _interfaceDefinitionHandler;
+
+      public TypeDefinitionVisitor (
+          Func<ClassDefinition, T?> classDefinitionHandler,
+          Func<InterfaceDefinition, T?> interfaceDefinitionHandler)
+      {
+        _classDefinitionHandler = classDefinitionHandler;
+        _interfaceDefinitionHandler = interfaceDefinitionHandler;
+      }
+
+      /// <inheritdoc />
+      public T? VisitClassDefinition (ClassDefinition classDefinition)
+      {
+        ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+
+        return _classDefinitionHandler(classDefinition);
+      }
+
+      public T? VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition)
+      {
+        ArgumentUtility.CheckNotNull("interfaceDefinition", interfaceDefinition);
+
+        return _interfaceDefinitionHandler(interfaceDefinition);
+      }
+    }
+
+    private class TypeDefinitionVisitor : ITypeDefinitionVisitor
+    {
+      private readonly Action<ClassDefinition> _classDefinitionHandler;
+      private readonly Action<InterfaceDefinition> _interfaceDefinitionHandler;
+
+      public TypeDefinitionVisitor (
+          Action<ClassDefinition> classDefinitionHandler,
+          Action<InterfaceDefinition> interfaceDefinitionHandler)
+      {
+        _classDefinitionHandler = classDefinitionHandler;
+        _interfaceDefinitionHandler = interfaceDefinitionHandler;
+      }
+
+      /// <inheritdoc />
+      public void VisitClassDefinition (ClassDefinition classDefinition)
+      {
+        ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+
+        _classDefinitionHandler(classDefinition);
+      }
+
+      /// <inheritdoc />
+      public void VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition)
+      {
+        ArgumentUtility.CheckNotNull("interfaceDefinition", interfaceDefinition);
+
+        _interfaceDefinitionHandler(interfaceDefinition);
+      }
+    }
+
+    public static T? Visit<T> (
+        TypeDefinition typeDefinition,
+        Func<ClassDefinition, T> classDefinitionHandler,
+        Func<InterfaceDefinition, T> interfaceDefinitionHandler)
+    {
+      ArgumentUtility.CheckNotNull(nameof(typeDefinition), typeDefinition);
+      ArgumentUtility.CheckNotNull(nameof(classDefinitionHandler), classDefinitionHandler);
+      ArgumentUtility.CheckNotNull(nameof(interfaceDefinitionHandler), interfaceDefinitionHandler);
+
+      var visitor = new TypeDefinitionVisitor<T>(classDefinitionHandler, interfaceDefinitionHandler);
+      return typeDefinition.Accept(visitor);
+    }
+
+    public static void Visit (
+        TypeDefinition typeDefinition,
+        Action<ClassDefinition> classDefinitionHandler,
+        Action<InterfaceDefinition> interfaceDefinitionHandler)
+    {
+      ArgumentUtility.CheckNotNull(nameof(typeDefinition), typeDefinition);
+      ArgumentUtility.CheckNotNull(nameof(classDefinitionHandler), classDefinitionHandler);
+      ArgumentUtility.CheckNotNull(nameof(interfaceDefinitionHandler), interfaceDefinitionHandler);
+
+      var visitor = new TypeDefinitionVisitor(classDefinitionHandler, interfaceDefinitionHandler);
+      typeDefinition.Accept(visitor);
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects/Mapping/InlineTypeDefinitionWalker.cs b/Remotion/Data/DomainObjects/Mapping/InlineTypeDefinitionWalker.cs
new file mode 100644
index 0000000000..a99f4d8d91
--- /dev/null
+++ b/Remotion/Data/DomainObjects/Mapping/InlineTypeDefinitionWalker.cs
@@ -0,0 +1,180 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using Remotion.Utilities;
+
+namespace Remotion.Data.DomainObjects.Mapping
+{
+  /// <summary>
+  /// Walks through the given <see cref="TypeDefinition"/>'s hierarchy and executes a handler based on the entity's type.
+  /// </summary>
+  public static class InlineTypeDefinitionWalker
+  {
+    private class InlineTypeDefinitionWalkerImplementation : TypeDefinitionWalker
+    {
+      private readonly Action<ClassDefinition> _classDefinitionHandler;
+      private readonly Action<InterfaceDefinition> _interfaceDefinitionHandler;
+
+      public InlineTypeDefinitionWalkerImplementation (
+          TypeDefinitionWalkerDirection direction,
+          Action<ClassDefinition> classDefinitionHandler,
+          Action<InterfaceDefinition> interfaceDefinitionHandler)
+          : base(direction)
+      {
+        _classDefinitionHandler = classDefinitionHandler;
+        _interfaceDefinitionHandler = interfaceDefinitionHandler;
+      }
+
+      /// <inheritdoc />
+      public override void VisitClassDefinition (ClassDefinition classDefinition)
+      {
+        ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+
+        _classDefinitionHandler(classDefinition);
+        base.VisitClassDefinition(classDefinition);
+      }
+
+      /// <inheritdoc />
+      public override void VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition)
+      {
+        ArgumentUtility.CheckNotNull("interfaceDefinition", interfaceDefinition);
+
+        _interfaceDefinitionHandler(interfaceDefinition);
+        base.VisitInterfaceDefinition(interfaceDefinition);
+      }
+    }
+
+    private class InlineTypeDefinitionWalkerImplementation<T> : TypeDefinitionWalker<T>
+    {
+      private readonly Func<ClassDefinition, T?> _classDefinitionHandler;
+      private readonly Func<InterfaceDefinition, T?> _interfaceDefinitionHandler;
+
+      public InlineTypeDefinitionWalkerImplementation (
+          TypeDefinitionWalkerDirection direction,
+          Func<ClassDefinition, T?> classDefinitionHandler,
+          Func<InterfaceDefinition, T?> interfaceDefinitionHandler,
+          Predicate<T?> match)
+          : base(direction, match)
+      {
+        _classDefinitionHandler = classDefinitionHandler;
+        _interfaceDefinitionHandler = interfaceDefinitionHandler;
+      }
+
+      /// <inheritdoc />
+      public override T? VisitClassDefinition (ClassDefinition classDefinition)
+      {
+        ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+
+        var result = _classDefinitionHandler(classDefinition);
+        if (Match(result))
+          return result;
+
+        return base.VisitClassDefinition(classDefinition);
+      }
+
+      /// <inheritdoc />
+      public override T? VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition)
+      {
+        ArgumentUtility.CheckNotNull("interfaceDefinition", interfaceDefinition);
+
+        var result = _interfaceDefinitionHandler(interfaceDefinition);
+        if (Match(result))
+          return result;
+
+        return base.VisitInterfaceDefinition(interfaceDefinition);
+      }
+    }
+
+    /// <summary>
+    /// Walks over the specified <paramref name="typeDefinition"/> and its ancestors, executing the specified handlers for each element.
+    /// </summary>
+    public static void WalkAncestors (
+        TypeDefinition typeDefinition,
+        Action<ClassDefinition> classDefinitionHandler,
+        Action<InterfaceDefinition> interfaceDefinitionHandler)
+    {
+      ArgumentUtility.CheckNotNull(nameof(typeDefinition), typeDefinition);
+      ArgumentUtility.CheckNotNull(nameof(classDefinitionHandler), classDefinitionHandler);
+      ArgumentUtility.CheckNotNull(nameof(interfaceDefinitionHandler), interfaceDefinitionHandler);
+
+      var inlineTypeDefinitionWalker = new InlineTypeDefinitionWalkerImplementation(TypeDefinitionWalkerDirection.Ascendants, classDefinitionHandler, interfaceDefinitionHandler);
+      typeDefinition.Accept(inlineTypeDefinitionWalker);
+    }
+
+    /// <summary>
+    /// Walks over the specified <paramref name="typeDefinition"/> and its ancestors, executing the specified handlers for each element
+    /// until <paramref name="match"/> returns <see langword="true"/> for one of the handler's results.
+    /// </summary>
+    public static T? WalkAncestors<T> (
+        TypeDefinition typeDefinition,
+        Func<ClassDefinition, T?> classDefinitionHandler,
+        Func<InterfaceDefinition, T?> interfaceDefinitionHandler,
+        Predicate<T?> match)
+    {
+      ArgumentUtility.CheckNotNull(nameof(typeDefinition), typeDefinition);
+      ArgumentUtility.CheckNotNull(nameof(classDefinitionHandler), classDefinitionHandler);
+      ArgumentUtility.CheckNotNull(nameof(interfaceDefinitionHandler), interfaceDefinitionHandler);
+      ArgumentUtility.CheckNotNull(nameof(match), match);
+
+      var inlineTypeDefinitionWalker = new InlineTypeDefinitionWalkerImplementation<T>(
+          TypeDefinitionWalkerDirection.Ascendants,
+          classDefinitionHandler,
+          interfaceDefinitionHandler,
+          match);
+      return typeDefinition.Accept(inlineTypeDefinitionWalker);
+    }
+
+    /// <summary>
+    /// Walks over the specified <paramref name="typeDefinition"/> and its descendants, executing the specified handlers for each element.
+    /// </summary>
+    public static void WalkDescendants (
+        TypeDefinition typeDefinition,
+        Action<ClassDefinition> classDefinitionHandler,
+        Action<InterfaceDefinition> interfaceDefinitionHandler)
+    {
+      ArgumentUtility.CheckNotNull(nameof(typeDefinition), typeDefinition);
+      ArgumentUtility.CheckNotNull(nameof(classDefinitionHandler), classDefinitionHandler);
+      ArgumentUtility.CheckNotNull(nameof(interfaceDefinitionHandler), interfaceDefinitionHandler);
+
+      var inlineTypeDefinitionWalker = new InlineTypeDefinitionWalkerImplementation(TypeDefinitionWalkerDirection.Descendants, classDefinitionHandler, interfaceDefinitionHandler);
+      typeDefinition.Accept(inlineTypeDefinitionWalker);
+    }
+
+    /// <summary>
+    /// Walks over the specified <paramref name="typeDefinition"/> and its descendants, executing the specified handlers for each element
+    /// until <paramref name="match"/> returns <see langword="true"/> for one of the handler's results.
+    /// </summary>
+    public static T? WalkDescendants<T> (
+        TypeDefinition typeDefinition,
+        Func<ClassDefinition, T?> classDefinitionHandler,
+        Func<InterfaceDefinition, T?> interfaceDefinitionHandler,
+        Predicate<T?> match)
+    {
+      ArgumentUtility.CheckNotNull(nameof(typeDefinition), typeDefinition);
+      ArgumentUtility.CheckNotNull(nameof(classDefinitionHandler), classDefinitionHandler);
+      ArgumentUtility.CheckNotNull(nameof(interfaceDefinitionHandler), interfaceDefinitionHandler);
+      ArgumentUtility.CheckNotNull(nameof(match), match);
+
+      var inlineTypeDefinitionWalker = new InlineTypeDefinitionWalkerImplementation<T>(
+          TypeDefinitionWalkerDirection.Descendants,
+          classDefinitionHandler,
+          interfaceDefinitionHandler,
+          match);
+      return typeDefinition.Accept(inlineTypeDefinitionWalker);
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects/Mapping/InterfaceDefinition.cs b/Remotion/Data/DomainObjects/Mapping/InterfaceDefinition.cs
new file mode 100644
index 0000000000..90de961350
--- /dev/null
+++ b/Remotion/Data/DomainObjects/Mapping/InterfaceDefinition.cs
@@ -0,0 +1,217 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Diagnostics;
+using System.Linq;
+using Remotion.Reflection;
+using Remotion.Utilities;
+
+namespace Remotion.Data.DomainObjects.Mapping
+{
+  [DebuggerDisplay("{GetType().Name} for {Type}")]
+  public class InterfaceDefinition : TypeDefinition
+  {
+    public ReadOnlyCollection<InterfaceDefinition> ExtendedInterfaces { get; }
+
+    private ReadOnlyCollection<ClassDefinition>? _implementingClasses;
+    private ReadOnlyCollection<InterfaceDefinition>? _extendingInterfaces;
+
+    public InterfaceDefinition (
+        Type type,
+        IEnumerable<InterfaceDefinition> extendedInterfaces,
+        Type? storageGroupType,
+        DefaultStorageClass defaultStorageClass)
+        : base(type, storageGroupType, defaultStorageClass)
+    {
+      ArgumentUtility.CheckNotNull(nameof(extendedInterfaces), extendedInterfaces);
+
+      var extendedInterfacesReadOnly = extendedInterfaces.ToList().AsReadOnly();
+      ArgumentUtility.CheckNotNullOrItemsNull(nameof(extendedInterfaces), extendedInterfacesReadOnly);
+
+      ExtendedInterfaces = extendedInterfacesReadOnly;
+    }
+
+    public ReadOnlyCollection<ClassDefinition> ImplementingClasses
+    {
+      get
+      {
+        if (_implementingClasses == null)
+          throw new InvalidOperationException($"No implementing classes have been set for interface '{Type.GetFullNameSafe()}'.");
+
+        return _implementingClasses;
+      }
+    }
+
+    public ReadOnlyCollection<InterfaceDefinition> ExtendingInterfaces
+    {
+      get
+      {
+        if (_extendingInterfaces == null)
+          throw new InvalidOperationException($"No extending interfaces have been set for interface '{Type.GetFullNameSafe()}'.");
+
+        return _extendingInterfaces;
+      }
+    }
+
+    public override bool IsPartOfInheritanceHierarchy => ExtendedInterfaces.Count > 0 || ImplementingClasses.Count > 0 || ExtendedInterfaces.Count > 0;
+
+    public void SetImplementingClasses (IEnumerable<ClassDefinition> implementingClasses)
+    {
+      ArgumentUtility.CheckNotNull(nameof(implementingClasses), implementingClasses);
+
+      if (IsReadOnly)
+        throw new NotSupportedException($"Interface '{Type.GetFullNameSafe()}' is read-only.");
+
+      var derivedClassesReadOnly = implementingClasses.ToList().AsReadOnly();
+      CheckImplementingClasses(derivedClassesReadOnly);
+
+      _implementingClasses = derivedClassesReadOnly;
+    }
+
+    public void SetExtendingInterfaces (IEnumerable<InterfaceDefinition> extendingInterfaces)
+    {
+      ArgumentUtility.CheckNotNull(nameof(extendingInterfaces), extendingInterfaces);
+
+      if (IsReadOnly)
+        throw new NotSupportedException($"Interface '{Type.GetFullNameSafe()}' is read-only.");
+
+      var derivedClassesReadOnly = extendingInterfaces.ToList().AsReadOnly();
+      CheckExtendingInterfaces(derivedClassesReadOnly);
+
+      _extendingInterfaces = derivedClassesReadOnly;
+    }
+
+    public override void Accept (ITypeDefinitionVisitor visitor)
+    {
+      ArgumentUtility.CheckNotNull("visitor", visitor);
+
+      visitor.VisitInterfaceDefinition(this);
+    }
+
+    public override T? Accept<T> (ITypeDefinitionVisitor<T> visitor)
+        where T : default
+    {
+      ArgumentUtility.CheckNotNull("visitor", visitor);
+
+      return visitor.VisitInterfaceDefinition(this);
+    }
+
+    public override void SetReadOnly ()
+    {
+      if (_implementingClasses == null)
+        throw new InvalidOperationException("Cannot set the type definition read-only as the implementing classes are not set.");
+      if (_extendingInterfaces == null)
+        throw new InvalidOperationException("Cannot set the type definition read-only as the extending interfaces are not set.");
+
+      base.SetReadOnly();
+    }
+
+    public override bool IsAssignableFrom (TypeDefinition other)
+    {
+      ArgumentUtility.CheckNotNull("other", other);
+
+      if (ReferenceEquals(this, other))
+        return true;
+
+      return ImplementingClasses.Any(e => e.IsAssignableFrom(other))
+             || ExtendingInterfaces.Any(e => e.IsAssignableFrom(other));
+    }
+
+    protected override void CheckPropertyDefinitions (IEnumerable<PropertyDefinition> propertyDefinitions)
+    {
+      foreach (var propertyDefinition in propertyDefinitions)
+      {
+        if (!ReferenceEquals(propertyDefinition.TypeDefinition, this))
+        {
+          throw new MappingException(
+              $"Property '{propertyDefinition.PropertyName}' cannot be added to interface '{Type.GetFullNameSafe()}',"
+              + $" because it was initialized for type '{propertyDefinition.TypeDefinition.Type.GetFullNameSafe()}'.");
+        }
+
+        foreach (var extendedInterface in ExtendedInterfaces)
+        {
+          var basePropertyDefinition = extendedInterface.GetPropertyDefinition(propertyDefinition.PropertyName);
+          if (basePropertyDefinition != null)
+          {
+            throw new MappingException(
+                $"Property '{propertyDefinition.PropertyName}' cannot be added to interface '{Type.GetFullNameSafe()}',"
+                + $" because extended interface '{basePropertyDefinition.TypeDefinition.Type.GetFullNameSafe()}' already defines a property with the same name.");
+          }
+        }
+      }
+    }
+
+    protected override void CheckRelationEndPointDefinitions (IEnumerable<IRelationEndPointDefinition> relationEndPoints)
+    {
+      foreach (var endPointDefinition in relationEndPoints)
+      {
+        var relationEndPointTypeDefinition = endPointDefinition.TypeDefinition;
+        var relationEndPointPropertyName = endPointDefinition.PropertyName;
+        Assertion.DebugAssert(endPointDefinition.IsAnonymous == false, "endPointDefinition.IsAnonymous == false");
+        Assertion.DebugIsNotNull(
+            relationEndPointPropertyName,
+            "endPointDefinition.PropertyName != null when endPointDefinition.IsAnonymous == false");
+
+        if (!ReferenceEquals(relationEndPointTypeDefinition, this))
+        {
+          throw new MappingException(
+              $"Relation end point for property '{relationEndPointPropertyName}' cannot be added to interface '{Type.GetFullNameSafe()}',"
+              + $" because it was initialized for interface '{relationEndPointTypeDefinition.Type.GetFullNameSafe()}'.");
+        }
+
+        foreach (var extendedInterface in ExtendedInterfaces)
+        {
+          var baseEndPointDefinition = extendedInterface.GetRelationEndPointDefinition(relationEndPointPropertyName);
+          if (baseEndPointDefinition != null)
+          {
+            throw new MappingException(
+                $"Relation end point for property '{relationEndPointPropertyName}' cannot be added to interface '{Type.GetFullNameSafe()}',"
+                + $" because extended interface '{baseEndPointDefinition.TypeDefinition.Type.GetFullNameSafe()}' already defines a relation end point with the same property name.");
+          }
+        }
+      }
+    }
+
+    private void CheckImplementingClasses (IEnumerable<ClassDefinition> implementingClasses)
+    {
+      foreach (var implementingClass in implementingClasses)
+      {
+        if (!implementingClass.ImplementedInterfaces.Contains(this))
+        {
+          throw new MappingException(
+              $"Interface '{Type.GetFullNameSafe()}' cannot be implemented by class '{implementingClass.Type.GetFullNameSafe()}', "
+              + $"because '{Type.Name}' is not contained in the list of implemented interfaces on '{implementingClass.Type.Name}'.");
+        }
+      }
+    }
+
+    private void CheckExtendingInterfaces (IEnumerable<InterfaceDefinition> extendingInterfaces)
+    {
+      foreach (var extendingInterface in extendingInterfaces)
+      {
+        if (!extendingInterface.ExtendedInterfaces.Contains(this))
+        {
+          throw new MappingException(
+              $"Interface '{Type.GetFullNameSafe()}' cannot be extended by interface '{extendingInterface.Type.GetFullNameSafe()}', "
+              + $"because '{Type.Name}' is not contained in the list of extended interfaces on '{extendingInterface.Type.Name}'.");
+        }
+      }
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects/Mapping/InvalidRelationEndPointDefinitionBase.cs b/Remotion/Data/DomainObjects/Mapping/InvalidRelationEndPointDefinitionBase.cs
index 5f2100ede0..d6b15b85b1 100644
--- a/Remotion/Data/DomainObjects/Mapping/InvalidRelationEndPointDefinitionBase.cs
+++ b/Remotion/Data/DomainObjects/Mapping/InvalidRelationEndPointDefinitionBase.cs
@@ -25,27 +25,27 @@ namespace Remotion.Data.DomainObjects.Mapping
   /// </summary>
   public abstract class InvalidRelationEndPointDefinitionBase : IRelationEndPointDefinition, IRelationEndPointDefinitionSetter
   {
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
     private readonly string _propertyName;
     private readonly Type _propertyType;
     private RelationDefinition? _relationDefinition;
     private readonly IPropertyInformation _propertyInformation;
 
-    protected InvalidRelationEndPointDefinitionBase (ClassDefinition classDefinition, string propertyName, Type propertyType)
+    protected InvalidRelationEndPointDefinitionBase (TypeDefinition typeDefinition, string propertyName, Type propertyType)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNull("propertyName", propertyName);
       ArgumentUtility.CheckNotNull("propertyType", propertyType);
 
-      _classDefinition = classDefinition;
+      _typeDefinition = typeDefinition;
       _propertyName = propertyName;
       _propertyType = propertyType;
-      _propertyInformation = new InvalidPropertyInformation(TypeAdapter.Create(_classDefinition.ClassType), propertyName, propertyType);
+      _propertyInformation = new InvalidPropertyInformation(TypeAdapter.Create(_typeDefinition.Type), propertyName, propertyType);
     }
 
-    public ClassDefinition ClassDefinition
+    public TypeDefinition TypeDefinition
     {
-      get { return _classDefinition; }
+      get { return _typeDefinition; }
     }
 
     public string PropertyName
diff --git a/Remotion/Data/DomainObjects/Mapping/MappingConfiguration.cs b/Remotion/Data/DomainObjects/Mapping/MappingConfiguration.cs
index 1c129c408c..648ce7866e 100644
--- a/Remotion/Data/DomainObjects/Mapping/MappingConfiguration.cs
+++ b/Remotion/Data/DomainObjects/Mapping/MappingConfiguration.cs
@@ -42,12 +42,12 @@ private class Fields
 
     private class Mapping
     {
-      public readonly ReadOnlyDictionary<Type, ClassDefinition> TypeDefinitions;
+      public readonly ReadOnlyDictionary<Type, TypeDefinition> TypeDefinitions;
       public readonly ReadOnlyDictionary<string, ClassDefinition> ClassDefinitions;
       public readonly ReadOnlyDictionary<string, RelationDefinition> RelationDefinitions;
 
       public Mapping (
-          ReadOnlyDictionary<Type, ClassDefinition> typeDefinitions,
+          ReadOnlyDictionary<Type, TypeDefinition> typeDefinitions,
           ReadOnlyDictionary<string, ClassDefinition> classDefinitions,
           ReadOnlyDictionary<string, RelationDefinition> relationDefinitions)
       {
@@ -127,12 +127,12 @@ private Mapping InitializeMapping (IMappingLoader mappingLoader, IPersistenceMod
       {
         var mappingConfigurationValidationHelper = new MappingConfigurationValidationHelper(mappingLoader, persistenceModelLoader);
 
-        var typeDefinitions = mappingLoader.GetClassDefinitions();
-        var typeDefinitionsDictionary = new ReadOnlyDictionary<Type, ClassDefinition>(typeDefinitions.ToDictionary(td => td.ClassType));
-        mappingConfigurationValidationHelper.ValidateDuplicateClassIDs(typeDefinitions.OfType<ClassDefinition>());
-        var classDefinitionsDictionary = new ReadOnlyDictionary<string, ClassDefinition>(typeDefinitions.ToDictionary(cd => cd.ID));
+        var typeDefinitions = mappingLoader.GetTypeDefinitions();
+        var typeDefinitionsDictionary = new ReadOnlyDictionary<Type, TypeDefinition>(typeDefinitions.ToDictionary(td => td.Type));
+        mappingConfigurationValidationHelper.ValidateDuplicateClassIDs(typeDefinitions);
+        var classDefinitionsDictionary = new ReadOnlyDictionary<string, ClassDefinition>(typeDefinitions.OfType<ClassDefinition>().ToDictionary(cd => cd.ID));
 
-        mappingConfigurationValidationHelper.ValidateClassDefinitions(typeDefinitionsDictionary.Values);
+        mappingConfigurationValidationHelper.ValidateTypeDefinitions(typeDefinitionsDictionary.Values);
         mappingConfigurationValidationHelper.ValidatePropertyDefinitions(typeDefinitionsDictionary.Values);
 
         var relationDefinitions = mappingLoader.GetRelationDefinitions(typeDefinitionsDictionary);
@@ -140,11 +140,11 @@ private Mapping InitializeMapping (IMappingLoader mappingLoader, IPersistenceMod
 
         mappingConfigurationValidationHelper.ValidateRelationDefinitions(relationDefinitionsDictionary.Values);
 
-        foreach (var rootClass in GetInheritanceRootClasses(typeDefinitionsDictionary.Values))
+        foreach (var inheritanceRoot in TypeDefinitionHierarchy.GetHierarchyRoots(typeDefinitionsDictionary.Values))
         {
-          persistenceModelLoader.ApplyPersistenceModelToHierarchy(rootClass);
-          mappingConfigurationValidationHelper.VerifyPersistenceModelApplied(rootClass);
-          mappingConfigurationValidationHelper.ValidatePersistenceMapping(rootClass);
+          persistenceModelLoader.ApplyPersistenceModelToHierarchy(inheritanceRoot);
+          mappingConfigurationValidationHelper.VerifyPersistenceModelApplied(inheritanceRoot);
+          mappingConfigurationValidationHelper.ValidatePersistenceMapping(inheritanceRoot);
         }
 
         foreach (var typeDefinition in typeDefinitionsDictionary.Values)
@@ -172,35 +172,28 @@ public bool ResolveTypes
       get { return _resolveTypes; }
     }
 
-    public ClassDefinition[] GetTypeDefinitions ()
+    public TypeDefinition[] GetTypeDefinitions ()
     {
       return _mapping.Value.TypeDefinitions.Values.ToArray();
     }
 
-    public bool ContainsTypeDefinition (Type classType)
+    public bool ContainsTypeDefinition (Type type)
     {
-      ArgumentUtility.CheckNotNull("classType", classType);
+      ArgumentUtility.CheckNotNull("type", type);
 
-      return _mapping.Value.TypeDefinitions.ContainsKey(classType);
+      return _mapping.Value.TypeDefinitions.ContainsKey(type);
     }
 
-    public ClassDefinition GetTypeDefinition (Type classType)
+    public TypeDefinition GetTypeDefinition (Type type, Func<Type, Exception> missingTypeDefinitionExceptionFactory)
     {
-      ArgumentUtility.CheckNotNull("classType", classType);
-
-      return GetTypeDefinition(classType, type => CreateMappingException("Mapping does not contain class '{0}'.", type));
-    }
-
-   public ClassDefinition GetTypeDefinition (Type classType, Func<Type, Exception> missingTypeDefinitionExceptionFactory)
-    {
-      ArgumentUtility.CheckNotNull("classType", classType);
+      ArgumentUtility.CheckNotNull("type", type);
       ArgumentUtility.CheckNotNull("missingTypeDefinitionExceptionFactory", missingTypeDefinitionExceptionFactory);
 
-      var classDefinition = _mapping.Value.TypeDefinitions.GetValueOrDefault(classType);
-      if (classDefinition == null)
-        throw missingTypeDefinitionExceptionFactory(classType);
+      var typeDefinition = _mapping.Value.TypeDefinitions.GetValueOrDefault(type);
+      if (typeDefinition == null)
+        throw missingTypeDefinitionExceptionFactory(type);
 
-      return classDefinition;
+      return typeDefinition;
     }
 
     public bool ContainsClassDefinition (string classID)
@@ -210,13 +203,6 @@ public bool ContainsClassDefinition (string classID)
       return _mapping.Value.ClassDefinitions.ContainsKey(classID);
     }
 
-    public ClassDefinition GetClassDefinition (string classID)
-    {
-      ArgumentUtility.CheckNotNullOrEmpty("classID", classID);
-
-      return GetClassDefinition(classID, id => CreateMappingException("Mapping does not contain class '{0}'.", id));
-    }
-
     public ClassDefinition GetClassDefinition (string classID, Func<string, Exception> missingClassDefinitionExceptionFactory)
     {
       ArgumentUtility.CheckNotNullOrEmpty("classID", classID);
@@ -234,19 +220,6 @@ public IMemberInformationNameResolver NameResolver
       get { return _nameResolver; }
     }
 
-    private IEnumerable<ClassDefinition> GetInheritanceRootClasses (IEnumerable<ClassDefinition> classDefinitions)
-    {
-      var rootClasses = new HashSet<ClassDefinition>();
-      foreach (var classDefinition in classDefinitions)
-      {
-        var rootClassDefinition = classDefinition.GetInheritanceRootClass();
-        if (!rootClasses.Contains(rootClassDefinition))
-          rootClasses.Add(rootClassDefinition);
-      }
-
-      return rootClasses;
-    }
-
     private MappingException CreateMappingException (string message, params object[] args)
     {
       return new MappingException(string.Format(message, args));
diff --git a/Remotion/Data/DomainObjects/Mapping/MappingConfigurationExtensions.cs b/Remotion/Data/DomainObjects/Mapping/MappingConfigurationExtensions.cs
new file mode 100644
index 0000000000..1b95001348
--- /dev/null
+++ b/Remotion/Data/DomainObjects/Mapping/MappingConfigurationExtensions.cs
@@ -0,0 +1,83 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using Remotion.Reflection;
+using Remotion.Utilities;
+
+namespace Remotion.Data.DomainObjects.Mapping
+{
+  /// <summary>
+  /// Provides extension methods used for <see cref="IMappingConfiguration"/>.
+  /// </summary>
+  public static class MappingConfigurationExtensions
+  {
+    public static TypeDefinition GetTypeDefinition (this IMappingConfiguration mappingConfiguration, Type type)
+    {
+      ArgumentUtility.CheckNotNull(nameof(mappingConfiguration), mappingConfiguration);
+      ArgumentUtility.CheckNotNull(nameof(type), type);
+
+      return mappingConfiguration.GetTypeDefinition(type, static type => CreateTypeMappingException(type.ToString()));
+    }
+
+    public static bool ContainsClassDefinition (this IMappingConfiguration mappingConfiguration, Type type)
+    {
+      ArgumentUtility.CheckNotNull(nameof(mappingConfiguration), mappingConfiguration);
+      ArgumentUtility.CheckNotNull(nameof(type), type);
+
+      return type.IsClass && mappingConfiguration.ContainsTypeDefinition(type);
+    }
+
+    public static ClassDefinition GetClassDefinition (this IMappingConfiguration mappingConfiguration, Type type)
+    {
+      ArgumentUtility.CheckNotNull(nameof(mappingConfiguration), mappingConfiguration);
+      ArgumentUtility.CheckNotNull(nameof(type), type);
+      if (!type.IsClass)
+        throw new ArgumentException($"The specified type '{type.GetFullNameSafe()}' must be a class.", nameof(type));
+
+      return (ClassDefinition)mappingConfiguration.GetTypeDefinition(type);
+    }
+
+    public static ClassDefinition GetClassDefinition (this IMappingConfiguration mappingConfiguration, Type type, Func<Type, Exception> missingClassDefinitionExceptionFactory)
+    {
+      ArgumentUtility.CheckNotNull(nameof(mappingConfiguration), mappingConfiguration);
+      ArgumentUtility.CheckNotNull(nameof(type), type);
+      ArgumentUtility.CheckNotNull(nameof(missingClassDefinitionExceptionFactory), missingClassDefinitionExceptionFactory);
+      if (!type.IsClass)
+        throw new ArgumentException($"The specified type '{type.GetFullNameSafe()}' must be a class.", nameof(type));
+
+      return (ClassDefinition)mappingConfiguration.GetTypeDefinition(type, missingClassDefinitionExceptionFactory);
+    }
+
+    public static ClassDefinition GetClassDefinition (this IMappingConfiguration mappingConfiguration, string classID)
+    {
+      ArgumentUtility.CheckNotNull(nameof(mappingConfiguration), mappingConfiguration);
+      ArgumentUtility.CheckNotNull(nameof(classID), classID);
+
+      return mappingConfiguration.GetClassDefinition(classID, static id => CreateClassMappingException(id));
+    }
+
+    private static MappingException CreateClassMappingException (string id)
+    {
+      return new MappingException($"Mapping does not contain class '{id}'.");
+    }
+
+    private static MappingException CreateTypeMappingException (string type)
+    {
+      return new MappingException($"Mapping does not contain type '{type}'.");
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects/Mapping/MappingConfigurationValidationHelper.cs b/Remotion/Data/DomainObjects/Mapping/MappingConfigurationValidationHelper.cs
index 49859fe923..438e7210e6 100644
--- a/Remotion/Data/DomainObjects/Mapping/MappingConfigurationValidationHelper.cs
+++ b/Remotion/Data/DomainObjects/Mapping/MappingConfigurationValidationHelper.cs
@@ -45,41 +45,48 @@ public MappingConfigurationValidationHelper (
       _persistenceModelValidatorFactory = persistenceModelValidatorFactory;
     }
 
-    public void VerifyPersistenceModelApplied (ClassDefinition classDefinition)
+    public void VerifyPersistenceModelApplied (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      if (!classDefinition.HasStorageEntityDefinitionBeenSet)
+      if (!typeDefinition.HasStorageEntityDefinitionBeenSet)
       {
-        var message = String.Format("The persistence model loader did not assign a storage entity to class '{0}'.", classDefinition.ID);
+        var message = String.Format("The persistence model loader did not assign a storage entity to type '{0}'.", typeDefinition.Type.GetFullNameSafe());
         throw new InvalidOperationException(message);
       }
 
-      foreach (PropertyDefinition propDef in classDefinition.MyPropertyDefinitions)
+      foreach (PropertyDefinition propDef in typeDefinition.MyPropertyDefinitions)
       {
         if (propDef.StorageClass == StorageClass.Persistent && propDef.StoragePropertyDefinition == null)
         {
           var message = String.Format(
-              "The persistence model loader did not assign a storage property to property '{0}' of class '{1}'.",
+              "The persistence model loader did not assign a storage property to property '{0}' of type '{1}'.",
               propDef.PropertyName,
-              classDefinition.ID);
+              typeDefinition.Type.GetFullNameSafe());
           throw new InvalidOperationException(message);
         }
       }
 
-      foreach (var derivedClass in classDefinition.DerivedClasses)
-        VerifyPersistenceModelApplied(derivedClass);
+      if (typeDefinition is ClassDefinition classDefinition)
+      {
+        foreach (var derivedClass in classDefinition.DerivedClasses)
+          VerifyPersistenceModelApplied(derivedClass);
+      }
+      else
+      {
+        throw new NotSupportedException("Only class definitions are supported"); // TODO R2I Mapping: Add support for interfaces
+      }
     }
 
-    public void ValidateClassDefinitions (IEnumerable<ClassDefinition> typeDefinitions)
+    public void ValidateTypeDefinitions (IEnumerable<TypeDefinition> typeDefinitions)
     {
       ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
-      var typeDefinitionValidator = _mappingValidatorFactory.CreateClassDefinitionValidator();
+      var typeDefinitionValidator = _mappingValidatorFactory.CreateTypeDefinitionValidator();
       AnalyzeMappingValidationResults(typeDefinitionValidator.Validate(typeDefinitions));
     }
 
-    public void ValidatePropertyDefinitions (IEnumerable<ClassDefinition> typeDefinitions)
+    public void ValidatePropertyDefinitions (IEnumerable<TypeDefinition> typeDefinitions)
     {
       ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
@@ -103,13 +110,13 @@ public void ValidateSortExpression (IEnumerable<RelationDefinition> relationDefi
       AnalyzeMappingValidationResults(sortExpressionValidator.Validate(relationDefinitions));
     }
 
-    public void ValidatePersistenceMapping (ClassDefinition rootClass)
+    public void ValidatePersistenceMapping (TypeDefinition rootType)
     {
-      ArgumentUtility.CheckNotNull("rootClass", rootClass);
+      ArgumentUtility.CheckNotNull("rootType", rootType);
 
-      var validator = _persistenceModelValidatorFactory.CreatePersistenceMappingValidator(rootClass);
-      var classDefinitionsToValidate = new[] { rootClass }.Concat(rootClass.GetAllDerivedClasses());
-      AnalyzeMappingValidationResults(validator.Validate(classDefinitionsToValidate));
+      var validator = _persistenceModelValidatorFactory.CreatePersistenceMappingValidator(rootType);
+      var typeDefinitionsToValidate = TypeDefinitionHierarchy.GetDescendantsAndSelf(rootType);
+      AnalyzeMappingValidationResults(validator.Validate(typeDefinitionsToValidate));
     }
 
     public void AnalyzeMappingValidationResults (IEnumerable<MappingValidationResult> mappingValidationResults)
@@ -121,11 +128,11 @@ public void AnalyzeMappingValidationResults (IEnumerable<MappingValidationResult
         throw CreateMappingException(mappingValidationResultsArray);
     }
 
-    public void ValidateDuplicateClassIDs (IEnumerable<ClassDefinition> classDefinitions)
+    public void ValidateDuplicateClassIDs (IEnumerable<TypeDefinition> typeDefinitions)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
-      var duplicateGroups = from cd in classDefinitions
+      var duplicateGroups = from cd in typeDefinitions.OfType<ClassDefinition>()
                             group cd by cd.ID
                             into cdGroups
                             where cdGroups.Count() > 1
@@ -136,11 +143,11 @@ where cdGroups.Count() > 1
         throw CreateMappingException(
             "Class '{0}' and '{1}' both have the same class ID '{2}'. Use the ClassIDAttribute to define unique IDs for these "
             + "classes. The assemblies involved are '{3}' and '{4}'.",
-            duplicates[0].ClassType.GetFullNameSafe(),
-            duplicates[1].ClassType.GetFullNameSafe(),
+            duplicates[0].Type.GetFullNameSafe(),
+            duplicates[1].Type.GetFullNameSafe(),
             duplicates[0].ID,
-            duplicates[0].ClassType.Assembly.GetFullNameSafe(),
-            duplicates[1].ClassType.Assembly.GetFullNameSafe());
+            duplicates[0].Type.Assembly.GetFullNameSafe(),
+            duplicates[1].Type.Assembly.GetFullNameSafe());
       }
     }
 
diff --git a/Remotion/Data/DomainObjects/Mapping/PersistenceModelLoader.cs b/Remotion/Data/DomainObjects/Mapping/PersistenceModelLoader.cs
index 2c6c4cc219..5aa7862469 100644
--- a/Remotion/Data/DomainObjects/Mapping/PersistenceModelLoader.cs
+++ b/Remotion/Data/DomainObjects/Mapping/PersistenceModelLoader.cs
@@ -38,23 +38,23 @@ public PersistenceModelLoader (IStorageSettings storageSettings)
       _storageSettings = storageSettings;
     }
 
-    public void ApplyPersistenceModelToHierarchy (ClassDefinition classDefinition)
+    public void ApplyPersistenceModelToHierarchy (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      var persistenceModelLoader = GetProviderSpecificPersistenceModelLoader(classDefinition);
-      persistenceModelLoader.ApplyPersistenceModelToHierarchy(classDefinition);
+      var persistenceModelLoader = GetProviderSpecificPersistenceModelLoader(typeDefinition);
+      persistenceModelLoader.ApplyPersistenceModelToHierarchy(typeDefinition);
     }
 
-    public IPersistenceMappingValidator CreatePersistenceMappingValidator (ClassDefinition classDefinition)
+    public IPersistenceMappingValidator CreatePersistenceMappingValidator (TypeDefinition typeDefinition)
     {
-      var persistenceModelLoader = GetProviderSpecificPersistenceModelLoader(classDefinition);
-      return persistenceModelLoader.CreatePersistenceMappingValidator(classDefinition);
+      var persistenceModelLoader = GetProviderSpecificPersistenceModelLoader(typeDefinition);
+      return persistenceModelLoader.CreatePersistenceMappingValidator(typeDefinition);
     }
 
-    private IPersistenceModelLoader GetProviderSpecificPersistenceModelLoader (ClassDefinition classDefinition)
+    private IPersistenceModelLoader GetProviderSpecificPersistenceModelLoader (TypeDefinition typeDefinition)
     {
-      var storageProviderDefinition = _storageSettings.GetStorageProviderDefinition(classDefinition);
+      var storageProviderDefinition = _storageSettings.GetStorageProviderDefinition(typeDefinition);
       return storageProviderDefinition.Factory.CreatePersistenceModelLoader(storageProviderDefinition);
     }
   }
diff --git a/Remotion/Data/DomainObjects/Mapping/PropertyAccessorDataCache.cs b/Remotion/Data/DomainObjects/Mapping/PropertyAccessorDataCache.cs
index d62d5f4fb6..484c85f376 100644
--- a/Remotion/Data/DomainObjects/Mapping/PropertyAccessorDataCache.cs
+++ b/Remotion/Data/DomainObjects/Mapping/PropertyAccessorDataCache.cs
@@ -29,21 +29,21 @@
 namespace Remotion.Data.DomainObjects.Mapping
 {
   /// <summary>
-  /// Holds all <see cref="PropertyAccessorData"/> object for a <see cref="ClassDefinition"/>, providing fast access via full property name or
+  /// Holds all <see cref="PropertyAccessorData"/> object for a <see cref="TypeDefinition"/>, providing fast access via full property name or
   /// declaring type and short (.NET) property name.
   /// </summary>
   public class PropertyAccessorDataCache
   {
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
     private readonly Lazy<IReadOnlyDictionary<string, PropertyAccessorData>> _cachedAccessorData;
     private readonly ConcurrentDictionary<IPropertyInformation, PropertyAccessorData?> _cachedAccessorDataByMember;
     private readonly Func<IPropertyInformation, PropertyAccessorData?> _resolvePropertyAccessorDataWithoutCacheFunc;
 
-    public PropertyAccessorDataCache (ClassDefinition classDefinition)
+    public PropertyAccessorDataCache (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      _classDefinition = classDefinition;
+      _typeDefinition = typeDefinition;
       _cachedAccessorData = new Lazy<IReadOnlyDictionary<string, PropertyAccessorData>>(
           BuildAccessorDataDictionary,
           LazyThreadSafetyMode.ExecutionAndPublication);
@@ -103,7 +103,7 @@ public PropertyAccessorDataCache (ClassDefinition classDefinition)
     [CanBeNull]
     private PropertyAccessorData? ResolvePropertyAccessorDataWithoutCache ([NotNull] IPropertyInformation propertyInformation)
     {
-      return ReflectionBasedPropertyResolver.ResolveDefinition(propertyInformation, _classDefinition, GetPropertyAccessorData);
+      return ReflectionBasedPropertyResolver.ResolveDefinition(propertyInformation, _typeDefinition, GetPropertyAccessorData);
     }
 
     [NotNull]
@@ -117,7 +117,7 @@ public PropertyAccessorData GetMandatoryPropertyAccessorData ([NotNull] string p
       {
         var message = string.Format(
             "The domain object type '{0}' does not have a mapping property named '{1}'.",
-            _classDefinition.ClassType,
+            _typeDefinition.Type,
             propertyName);
         throw new MappingException(message);
       }
@@ -147,7 +147,7 @@ public PropertyAccessorData ResolveMandatoryPropertyAccessorData<TDomainObject,
       {
         var message = string.Format(
             "The domain object type '{0}' does not have a mapping property identified by expression '{1}'.",
-            _classDefinition.ClassType,
+            _typeDefinition.Type,
             propertyAccessExpression);
         throw new MappingException(message);
       }
@@ -182,8 +182,8 @@ private string GetIdentifierFromTypeAndShortName ([NotNull] Type domainObjectTyp
 
     private Dictionary<string, PropertyAccessorData> BuildAccessorDataDictionary ()
     {
-      var propertyDefinitions = _classDefinition.GetPropertyDefinitions();
-      var relationEndPointDefinitions = _classDefinition.GetRelationEndPointDefinitions();
+      var propertyDefinitions = _typeDefinition.GetPropertyDefinitions();
+      var relationEndPointDefinitions = _typeDefinition.GetRelationEndPointDefinitions();
 
       var propertyDefinitionNames = from PropertyDefinition pd in propertyDefinitions
                                     select pd.PropertyName;
@@ -193,7 +193,7 @@ where repd.IsVirtual
           select (string)repd.PropertyName!;
 
       var allPropertyNames = propertyDefinitionNames.Concat(virtualRelationEndPointNames);
-      var allPropertyAccessorData = allPropertyNames.Select(name => new PropertyAccessorData(_classDefinition, name));
+      var allPropertyAccessorData = allPropertyNames.Select(name => new PropertyAccessorData(_typeDefinition, name));
       return allPropertyAccessorData.ToDictionary(data => data.PropertyIdentifier);
     }
   }
diff --git a/Remotion/Data/DomainObjects/Mapping/PropertyDefinition.cs b/Remotion/Data/DomainObjects/Mapping/PropertyDefinition.cs
index d6ca5aa108..1890050905 100644
--- a/Remotion/Data/DomainObjects/Mapping/PropertyDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/PropertyDefinition.cs
@@ -26,7 +26,7 @@ namespace Remotion.Data.DomainObjects.Mapping
   public class PropertyDefinition
   {
     private readonly string _propertyName;
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
     private readonly int? _maxLength;
     private readonly StorageClass _storageClass;
     private IStoragePropertyDefinition? _storagePropertyDefinition;
@@ -38,7 +38,7 @@ public class PropertyDefinition
     private readonly object? _defaultValue;
 
     public PropertyDefinition (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         IPropertyInformation propertyInfo,
         string propertyName,
         bool isObjectID,
@@ -47,11 +47,11 @@ public PropertyDefinition (
         StorageClass storageClass,
         object? defaultValue)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNullOrEmpty("propertyName", propertyName);
       ArgumentUtility.CheckNotNull("propertyInfo", propertyInfo);
 
-      _classDefinition = classDefinition;
+      _typeDefinition = typeDefinition;
       _propertyInfo = propertyInfo;
       _propertyType = isObjectID ? typeof(ObjectID) : propertyInfo.PropertyType;
       _propertyName = propertyName;
@@ -63,9 +63,9 @@ public PropertyDefinition (
       _defaultValue = defaultValue;
     }
 
-    public ClassDefinition ClassDefinition
+    public TypeDefinition TypeDefinition
     {
-      get { return _classDefinition; }
+      get { return _typeDefinition; }
     }
 
     public string PropertyName
@@ -85,7 +85,7 @@ public IStoragePropertyDefinition StoragePropertyDefinition
         if (StorageClass != StorageClass.Persistent)
           throw new InvalidOperationException("Cannot access property 'storagePropertyDefinition' for non-persistent property definitions.");
 
-        Assertion.IsNotNull(_storagePropertyDefinition, "StoragePropertyDefinition has not been set for property '{0}' of class '{1}'.", PropertyName, _classDefinition.ID);
+        Assertion.IsNotNull(_storagePropertyDefinition, "StoragePropertyDefinition has not been set for property '{0}' of type '{1}'.", PropertyName, _typeDefinition.Type.GetFullNameSafe());
         return _storagePropertyDefinition;
       }
     }
diff --git a/Remotion/Data/DomainObjects/Mapping/PropertyDefinitionCollection.cs b/Remotion/Data/DomainObjects/Mapping/PropertyDefinitionCollection.cs
index 530ff6f9b5..a02dc8eeb8 100644
--- a/Remotion/Data/DomainObjects/Mapping/PropertyDefinitionCollection.cs
+++ b/Remotion/Data/DomainObjects/Mapping/PropertyDefinitionCollection.cs
@@ -26,11 +26,17 @@ namespace Remotion.Data.DomainObjects.Mapping
   [Serializable]
   public class PropertyDefinitionCollection : CommonCollection, IEnumerable<PropertyDefinition>
   {
-    public static PropertyDefinitionCollection CreateForAllProperties (ClassDefinition classDefinition, bool makeCollectionReadOnly)
+    public static PropertyDefinitionCollection CreateForAllProperties (TypeDefinition typeDefinition, bool makeCollectionReadOnly)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
-      return new PropertyDefinitionCollection(
-          classDefinition.CreateSequence(cd => cd.BaseClass).SelectMany(cd => cd.MyPropertyDefinitions), makeCollectionReadOnly);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
+
+      var properties = new List<PropertyDefinition>();
+      InlineTypeDefinitionWalker.WalkAncestors(
+          typeDefinition,
+          classDefinition => properties.AddRange(classDefinition.MyPropertyDefinitions),
+          interfaceDefinition => properties.AddRange(interfaceDefinition.MyPropertyDefinitions));
+
+      return new PropertyDefinitionCollection(properties, makeCollectionReadOnly);
     }
 
     public PropertyDefinitionCollection ()
diff --git a/Remotion/Data/DomainObjects/Mapping/PropertyDefinitionCollectionFactory.cs b/Remotion/Data/DomainObjects/Mapping/PropertyDefinitionCollectionFactory.cs
index ae3cf6967b..1fdb327a0a 100644
--- a/Remotion/Data/DomainObjects/Mapping/PropertyDefinitionCollectionFactory.cs
+++ b/Remotion/Data/DomainObjects/Mapping/PropertyDefinitionCollectionFactory.cs
@@ -37,14 +37,14 @@ public PropertyDefinitionCollectionFactory (IMappingObjectFactory mappingObjectF
       _mappingObjectFactory = mappingObjectFactory;
     }
 
-    public PropertyDefinitionCollection CreatePropertyDefinitions (ClassDefinition classDefinition, IEnumerable<IPropertyInformation> propertyInfos)
+    public PropertyDefinitionCollection CreatePropertyDefinitions (TypeDefinition typeDefinition, IEnumerable<IPropertyInformation> propertyInfos)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNull("propertyInfos", propertyInfos);
 
       var propertyDefinitionsForClass =
           from IPropertyInformation propertyInfo in propertyInfos
-          select _mappingObjectFactory.CreatePropertyDefinition(classDefinition, propertyInfo);
+          select _mappingObjectFactory.CreatePropertyDefinition(typeDefinition, propertyInfo);
       return new PropertyDefinitionCollection(propertyDefinitionsForClass, true);
     }
   }
diff --git a/Remotion/Data/DomainObjects/Mapping/PropertyNotFoundRelationEndPointDefinition.cs b/Remotion/Data/DomainObjects/Mapping/PropertyNotFoundRelationEndPointDefinition.cs
index 01cc8cc8db..2a79699662 100644
--- a/Remotion/Data/DomainObjects/Mapping/PropertyNotFoundRelationEndPointDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/PropertyNotFoundRelationEndPointDefinition.cs
@@ -23,8 +23,8 @@ namespace Remotion.Data.DomainObjects.Mapping
   /// </summary>
   public class PropertyNotFoundRelationEndPointDefinition : InvalidRelationEndPointDefinitionBase
   {
-    public PropertyNotFoundRelationEndPointDefinition (ClassDefinition classDefinition, string propertyName, Type propertyType)
-        : base(classDefinition, propertyName, propertyType)
+    public PropertyNotFoundRelationEndPointDefinition (TypeDefinition typeDefinition, string propertyName, Type propertyType)
+        : base(typeDefinition, propertyName, propertyType)
     {
     }
   }
diff --git a/Remotion/Data/DomainObjects/Mapping/ReflectionBasedMappingObjectFactory.cs b/Remotion/Data/DomainObjects/Mapping/ReflectionBasedMappingObjectFactory.cs
index 3da78a9e66..05d3835367 100644
--- a/Remotion/Data/DomainObjects/Mapping/ReflectionBasedMappingObjectFactory.cs
+++ b/Remotion/Data/DomainObjects/Mapping/ReflectionBasedMappingObjectFactory.cs
@@ -78,13 +78,13 @@ public ClassDefinition CreateClassDefinition (Type type, ClassDefinition? baseCl
       return classReflector.GetMetadata(baseClass);
     }
 
-    public PropertyDefinition CreatePropertyDefinition (ClassDefinition classDefinition, IPropertyInformation propertyInfo)
+    public PropertyDefinition CreatePropertyDefinition (TypeDefinition typeDefinition, IPropertyInformation propertyInfo)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNull("propertyInfo", propertyInfo);
 
       var propertyReflector = new PropertyReflector(
-          classDefinition,
+          typeDefinition,
           propertyInfo,
           _nameResolver,
           _propertyMetadataProvider,
@@ -94,23 +94,23 @@ public PropertyDefinition CreatePropertyDefinition (ClassDefinition classDefinit
     }
 
     public RelationDefinition CreateRelationDefinition (
-        IDictionary<Type, ClassDefinition> classDefinitions, ClassDefinition classDefinition, IPropertyInformation propertyInfo)
+        IDictionary<Type, TypeDefinition> typeDefinitions, TypeDefinition typeDefinition, IPropertyInformation propertyInfo)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNull("propertyInfo", propertyInfo);
 
-      var relationReflector = new RelationReflector(classDefinition, propertyInfo, _nameResolver, _propertyMetadataProvider);
-      return relationReflector.GetMetadata(classDefinitions);
+      var relationReflector = new RelationReflector(typeDefinition, propertyInfo, _nameResolver, _propertyMetadataProvider);
+      return relationReflector.GetMetadata(typeDefinitions);
     }
 
-    public IRelationEndPointDefinition CreateRelationEndPointDefinition (ClassDefinition classDefinition, IPropertyInformation propertyInfo)
+    public IRelationEndPointDefinition CreateRelationEndPointDefinition (TypeDefinition typeDefinition, IPropertyInformation propertyInfo)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNull("propertyInfo", propertyInfo);
 
       var relationEndPointReflector = RelationEndPointReflector.CreateRelationEndPointReflector(
-          classDefinition,
+          typeDefinition,
           propertyInfo,
           _nameResolver,
           _propertyMetadataProvider,
@@ -119,7 +119,7 @@ public IRelationEndPointDefinition CreateRelationEndPointDefinition (ClassDefini
       return relationEndPointReflector.GetMetadata();
     }
 
-    public ClassDefinition[] CreateClassDefinitionCollection (IEnumerable<Type> types)
+    public TypeDefinition[] CreateTypeDefinitionCollection (IEnumerable<Type> types)
     {
       ArgumentUtility.CheckNotNull("types", types);
 
@@ -128,29 +128,29 @@ public ClassDefinition[] CreateClassDefinitionCollection (IEnumerable<Type> type
     }
 
     public PropertyDefinitionCollection CreatePropertyDefinitionCollection (
-        ClassDefinition classDefinition, IEnumerable<IPropertyInformation> propertyInfos)
+        TypeDefinition typeDefinition, IEnumerable<IPropertyInformation> propertyInfos)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNull("propertyInfos", propertyInfos);
 
       var factory = new PropertyDefinitionCollectionFactory(this);
-      return factory.CreatePropertyDefinitions(classDefinition, propertyInfos);
+      return factory.CreatePropertyDefinitions(typeDefinition, propertyInfos);
     }
 
-    public RelationDefinition[] CreateRelationDefinitionCollection (IDictionary<Type, ClassDefinition> classDefinitions)
+    public RelationDefinition[] CreateRelationDefinitionCollection (IDictionary<Type, TypeDefinition> typeDefinitions)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
       var factory = new RelationDefinitionCollectionFactory(this);
-      return factory.CreateRelationDefinitionCollection(classDefinitions);
+      return factory.CreateRelationDefinitionCollection(typeDefinitions);
     }
 
-    public RelationEndPointDefinitionCollection CreateRelationEndPointDefinitionCollection (ClassDefinition classDefinition)
+    public RelationEndPointDefinitionCollection CreateRelationEndPointDefinitionCollection (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
       var factory = new RelationEndPointDefinitionCollectionFactory(this, _nameResolver, _propertyMetadataProvider);
-      return factory.CreateRelationEndPointDefinitionCollection(classDefinition);
+      return factory.CreateRelationEndPointDefinitionCollection(typeDefinition);
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/ReflectionBasedPropertyResolver.cs b/Remotion/Data/DomainObjects/Mapping/ReflectionBasedPropertyResolver.cs
index 1f3276e9b9..dbfe10fecc 100644
--- a/Remotion/Data/DomainObjects/Mapping/ReflectionBasedPropertyResolver.cs
+++ b/Remotion/Data/DomainObjects/Mapping/ReflectionBasedPropertyResolver.cs
@@ -25,16 +25,19 @@
 namespace Remotion.Data.DomainObjects.Mapping
 {
   /// <summary>
-  /// Provides functionality to resolve <see cref="PropertyInfo"/> objects into child objects of <see cref="ClassDefinition"/>.
+  /// Provides functionality to resolve <see cref="PropertyInfo"/> objects into child objects of <see cref="TypeDefinition"/>.
   /// </summary>
   public static class ReflectionBasedPropertyResolver
   {
-    public static T? ResolveDefinition<T> (IPropertyInformation propertyInformation, ClassDefinition classDefinition, Func<string, T?> definitionGetter)
+    public static T? ResolveDefinition<T> (IPropertyInformation propertyInformation, TypeDefinition typeDefinition, Func<string, T?> definitionGetter)
         where T : class
     {
       ArgumentUtility.CheckNotNull("propertyInformation", propertyInformation);
       ArgumentUtility.CheckNotNull("definitionGetter", definitionGetter);
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
+
+      if (typeDefinition is not ClassDefinition classDefinition) // TODO R2I Mapping: Interface support in reflection loader
+        throw new InvalidOperationException("TODO Relations to Interfaces: Only class definitions are supported at this time.");
 
       var matchingImplementations = GetMatchingDefinitions(propertyInformation, classDefinition, definitionGetter);
 
@@ -44,7 +47,7 @@ public static class ReflectionBasedPropertyResolver
         var message = string.Format(
             "The property '{0}' is ambiguous, it is implemented by the following types valid in the context of class '{1}': {2}.",
             propertyInformation.Name,
-            classDefinition.ClassType.Name,
+            classDefinition.Type.Name,
             string.Join(", ", implementingTypeNames));
         throw new InvalidOperationException(message);
       }
@@ -52,7 +55,7 @@ public static class ReflectionBasedPropertyResolver
       return matchingImplementations.Select(tuple => tuple.Item2).SingleOrDefault();
     }
 
-    private static List<ValueTuple<IPropertyInformation, T>> GetMatchingDefinitions<T> (
+    private static List<(IPropertyInformation, T)> GetMatchingDefinitions<T> (
         IPropertyInformation propertyInformation,
         ClassDefinition classDefinition,
         Func<string, T?> definitionGetter) where T: class
@@ -86,8 +89,8 @@ private static IEnumerable<Type> GetImplementingTypes (ClassDefinition classDefi
     {
       Assertion.IsTrue(interfaceProperty.DeclaringType!.IsInterface);
 
-      if (interfaceProperty.DeclaringType.IsAssignableFrom(TypeAdapter.Create(classDefinition.ClassType)))
-        yield return classDefinition.ClassType;
+      if (interfaceProperty.DeclaringType.IsAssignableFrom(TypeAdapter.Create(classDefinition.Type)))
+        yield return classDefinition.Type;
 
       var implementingPersistentMixins =
           from cd in classDefinition.CreateSequence(cd => cd.BaseClass)
diff --git a/Remotion/Data/DomainObjects/Mapping/RelationDefinition.cs b/Remotion/Data/DomainObjects/Mapping/RelationDefinition.cs
index ec6b6fe2cd..b993cbb064 100644
--- a/Remotion/Data/DomainObjects/Mapping/RelationDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/RelationDefinition.cs
@@ -15,6 +15,7 @@
 // along with re-motion; if not, see http://www.gnu.org/licenses.
 // 
 using System;
+using Remotion.Reflection;
 using Remotion.Utilities;
 
 namespace Remotion.Data.DomainObjects.Mapping
@@ -49,9 +50,9 @@ public IRelationEndPointDefinition GetMandatoryOppositeRelationEndPointDefinitio
       if (oppositeEndPointDefinition == null)
       {
         throw CreateMappingException(
-            "Relation '{0}' has no association with class '{1}' and property '{2}'.",
+            "Relation '{0}' has no association with type '{1}' and property '{2}'.",
             ID,
-            endPointDefinition.ClassDefinition.ID,
+            endPointDefinition.TypeDefinition.Type.GetFullNameSafe(),
             endPointDefinition.PropertyName);
       }
 
@@ -81,14 +82,14 @@ public IRelationEndPointDefinition[] EndPointDefinitions
       get { return new[] { _endPointDefinition1, _endPointDefinition2 }; }
     }
 
-    public IRelationEndPointDefinition? GetEndPointDefinition (string classID, string propertyName)
+    public IRelationEndPointDefinition? GetEndPointDefinition (Type type, string propertyName)
     {
-      ArgumentUtility.CheckNotNullOrEmpty("classID", classID);
+      ArgumentUtility.CheckNotNull("type", type);
 
-      if (_endPointDefinition1.ClassDefinition.ID == classID && _endPointDefinition1.PropertyName == propertyName)
+      if (_endPointDefinition1.TypeDefinition.Type == type && _endPointDefinition1.PropertyName == propertyName)
         return _endPointDefinition1;
 
-      if (_endPointDefinition2.ClassDefinition.ID == classID && _endPointDefinition2.PropertyName == propertyName)
+      if (_endPointDefinition2.TypeDefinition.Type == type && _endPointDefinition2.PropertyName == propertyName)
         return _endPointDefinition2;
 
       return null;
@@ -106,22 +107,22 @@ public IRelationEndPointDefinition[] EndPointDefinitions
         return null;
     }
 
-    public IRelationEndPointDefinition? GetOppositeEndPointDefinition (string classID, string propertyName)
+    public IRelationEndPointDefinition? GetOppositeEndPointDefinition (Type type, string propertyName)
     {
-      ArgumentUtility.CheckNotNullOrEmpty("classID", classID);
+      ArgumentUtility.CheckNotNull("type", type);
 
-      var matchingEndPointDefinition = GetEndPointDefinition(classID, propertyName);
+      var matchingEndPointDefinition = GetEndPointDefinition(type, propertyName);
       if (matchingEndPointDefinition == null)
         return null;
 
       return GetOppositeEndPointDefinition(matchingEndPointDefinition);
     }
 
-    public bool IsEndPoint (string classID, string propertyName)
+    public bool IsEndPoint (Type type, string propertyName)
     {
-      ArgumentUtility.CheckNotNullOrEmpty("classID", classID);
+      ArgumentUtility.CheckNotNull("type", type);
 
-      return GetEndPointDefinition(classID, propertyName) != null;
+      return GetEndPointDefinition(type, propertyName) != null;
     }
 
     public bool Contains (IRelationEndPointDefinition endPointDefinition)
diff --git a/Remotion/Data/DomainObjects/Mapping/RelationDefinitionCollectionFactory.cs b/Remotion/Data/DomainObjects/Mapping/RelationDefinitionCollectionFactory.cs
index 7a54d409d9..a6c318fb9c 100644
--- a/Remotion/Data/DomainObjects/Mapping/RelationDefinitionCollectionFactory.cs
+++ b/Remotion/Data/DomainObjects/Mapping/RelationDefinitionCollectionFactory.cs
@@ -23,7 +23,7 @@ namespace Remotion.Data.DomainObjects.Mapping
 {
   /// <summary>
   /// The <see cref="RelationDefinitionCollectionFactory"/> is used to get a sequence of <see cref="RelationDefinition"/> objects for a set of 
-  /// <see cref="ClassDefinition"/>s.
+  /// <see cref="TypeDefinition"/>s.
   /// sets base classes and derived classes correctly.
   /// </summary>
   public class RelationDefinitionCollectionFactory
@@ -37,26 +37,26 @@ public RelationDefinitionCollectionFactory (IMappingObjectFactory mappingObjectF
       _mappingObjectFactory = mappingObjectFactory;
     }
 
-    public RelationDefinition[] CreateRelationDefinitionCollection (IDictionary<Type, ClassDefinition> classDefinitions)
+    public RelationDefinition[] CreateRelationDefinitionCollection (IDictionary<Type, TypeDefinition> typeDefinitions)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
       var relationDefinitions = new Dictionary<string, RelationDefinition>();
-      foreach (var classDefinition in classDefinitions.Values)
-        GetRelationDefinitions(classDefinitions, classDefinition, relationDefinitions);
+      foreach (var typeDefinition in typeDefinitions.Values)
+        GetRelationDefinitions(typeDefinitions, typeDefinition, relationDefinitions);
 
       return relationDefinitions.Values.ToArray();
     }
 
     private void GetRelationDefinitions (
-        IDictionary<Type, ClassDefinition> classDefinitions,
-        ClassDefinition classDefinition,
+        IDictionary<Type, TypeDefinition> typeDefinitions,
+        TypeDefinition typeDefinition,
         IDictionary<string, RelationDefinition> relationDefinitions)
     {
-      foreach (var endPoint in classDefinition.MyRelationEndPointDefinitions)
+      foreach (var endPoint in typeDefinition.MyRelationEndPointDefinitions)
       {
         Assertion.DebugAssert(endPoint.IsAnonymous == false, "endPoint.IsAnonymous == false");
-        var relationDefinition = _mappingObjectFactory.CreateRelationDefinition(classDefinitions, classDefinition, endPoint.PropertyInfo);
+        var relationDefinition = _mappingObjectFactory.CreateRelationDefinition(typeDefinitions, typeDefinition, endPoint.PropertyInfo);
         if (!relationDefinitions.ContainsKey(relationDefinition.ID))
         {
           ((IRelationEndPointDefinitionSetter)relationDefinition.EndPointDefinitions[0]).SetRelationDefinition(relationDefinition);
diff --git a/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinition.cs b/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinition.cs
index e7431f10c2..a3e4767f4a 100644
--- a/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinition.cs
@@ -28,7 +28,7 @@ namespace Remotion.Data.DomainObjects.Mapping
   public class RelationEndPointDefinition : IRelationEndPointDefinition, IRelationEndPointDefinitionSetter
   {
     private RelationDefinition? _relationDefinition;
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
     private readonly PropertyDefinition _propertyDefinition;
     private readonly bool _isMandatory;
 
@@ -39,14 +39,14 @@ public RelationEndPointDefinition (PropertyDefinition propertyDefinition, bool i
       if (!propertyDefinition.IsObjectID)
       {
         throw CreateMappingException(
-            "Relation definition error: Property '{0}' of class '{1}' is of type '{2}', but non-virtual properties must be of type '{3}'.",
+            "Relation definition error: Property '{0}' of type '{1}' is of type '{2}', but non-virtual properties must be of type '{3}'.",
             propertyDefinition.PropertyName,
-            propertyDefinition.ClassDefinition.ID,
+            propertyDefinition.TypeDefinition.Type.GetFullNameSafe(),
             propertyDefinition.PropertyType,
             typeof(ObjectID));
       }
 
-      _classDefinition = propertyDefinition.ClassDefinition;
+      _typeDefinition = propertyDefinition.TypeDefinition;
       _isMandatory = isMandatory;
       _propertyDefinition = propertyDefinition;
     }
@@ -72,9 +72,15 @@ public RelationDefinition RelationDefinition
       }
     }
 
-    public ClassDefinition ClassDefinition
+    [Obsolete("Use RelationEndPointDefinition.TypeDefinition instead. (Version 7.0.0)")]
+    public TypeDefinition ClassDefinition
     {
-      get { return _classDefinition; }
+      get { return TypeDefinition; }
+    }
+
+    public TypeDefinition TypeDefinition
+    {
+      get { return _typeDefinition; }
     }
 
     public string PropertyName
diff --git a/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionCollection.cs b/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionCollection.cs
index 076e752bd5..c00dc46c01 100644
--- a/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionCollection.cs
+++ b/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionCollection.cs
@@ -26,13 +26,17 @@ namespace Remotion.Data.DomainObjects.Mapping
   [Serializable]
   public class RelationEndPointDefinitionCollection : CommonCollection, IEnumerable<IRelationEndPointDefinition>
   {
-    public static RelationEndPointDefinitionCollection CreateForAllRelationEndPoints (ClassDefinition classDefinition, bool makeCollectionReadOnly)
+    public static RelationEndPointDefinitionCollection CreateForAllRelationEndPoints (TypeDefinition typeDefinition, bool makeCollectionReadOnly)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return
-          new RelationEndPointDefinitionCollection(
-              classDefinition.CreateSequence(cd => cd.BaseClass).SelectMany(cd => cd.MyRelationEndPointDefinitions), makeCollectionReadOnly);
+      var endPoints = new List<IRelationEndPointDefinition>();
+      InlineTypeDefinitionWalker.WalkAncestors(
+          typeDefinition,
+          classDefinition => endPoints.AddRange(classDefinition.MyRelationEndPointDefinitions),
+          interfaceDefinition => endPoints.AddRange(interfaceDefinition.MyRelationEndPointDefinitions));
+
+      return new RelationEndPointDefinitionCollection(endPoints, makeCollectionReadOnly);
     }
 
     public RelationEndPointDefinitionCollection ()
diff --git a/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionCollectionFactory.cs b/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionCollectionFactory.cs
index 13ad332873..d99b922e9c 100644
--- a/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionCollectionFactory.cs
+++ b/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionCollectionFactory.cs
@@ -24,7 +24,7 @@ namespace Remotion.Data.DomainObjects.Mapping
 {
   /// <summary>
   /// The <see cref="RelationEndPointDefinitionCollectionFactory"/> is used to get a <see cref="RelationEndPointDefinitionCollection"/> for a 
-  /// <see cref="ClassDefinition"/>
+  /// <see cref="TypeDefinition"/>
   /// </summary>
   public class RelationEndPointDefinitionCollectionFactory
   {
@@ -46,28 +46,37 @@ public RelationEndPointDefinitionCollectionFactory (
       _propertyMetadataProvider = propertyMetadataProvider;
     }
 
-    public RelationEndPointDefinitionCollection CreateRelationEndPointDefinitionCollection (ClassDefinition classDefinition)
+    public RelationEndPointDefinitionCollection CreateRelationEndPointDefinitionCollection (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
       var endPoints = new RelationEndPointDefinitionCollection();
-      foreach (var propertyInfo in GetRelationPropertyInfos(classDefinition))
+      foreach (var propertyInfo in GetRelationPropertyInfos(typeDefinition))
       {
-        var relationEndPoint = _mappingObjectFactory.CreateRelationEndPointDefinition(classDefinition, propertyInfo);
+        var relationEndPoint = _mappingObjectFactory.CreateRelationEndPointDefinition(typeDefinition, propertyInfo);
         endPoints.Add(relationEndPoint);
       }
       return endPoints;
     }
 
-    private IEnumerable<IPropertyInformation> GetRelationPropertyInfos (ClassDefinition classDefinition)
+    private IEnumerable<IPropertyInformation> GetRelationPropertyInfos (TypeDefinition typeDefinition)
     {
-      var relationPropertyFinder = new RelationPropertyFinder(
-          classDefinition.ClassType,
-          classDefinition.BaseClass == null,
-          true,
-          _nameResolver,
-          classDefinition.PersistentMixinFinder,
-          _propertyMetadataProvider);
+      RelationPropertyFinder relationPropertyFinder;
+      if (typeDefinition is ClassDefinition classDefinition)
+      {
+        relationPropertyFinder = new RelationPropertyFinder(
+            classDefinition.Type,
+            classDefinition.BaseClass == null,
+            true,
+            _nameResolver,
+            classDefinition.PersistentMixinFinder,
+            _propertyMetadataProvider);
+      }
+      else
+      {
+        throw new NotSupportedException("Only class definitions are supported."); // TODO R2I Mapping: property finder support for interfaces
+      }
+
       return relationPropertyFinder.FindPropertyInfos();
     }
   }
diff --git a/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionExtensions.cs b/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionExtensions.cs
index 2c369eb1cc..3c873eaa93 100644
--- a/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionExtensions.cs
+++ b/Remotion/Data/DomainObjects/Mapping/RelationEndPointDefinitionExtensions.cs
@@ -34,11 +34,18 @@ public static IRelationEndPointDefinition GetOppositeEndPointDefinition (this IR
       return oppositeEndPointDefinition;
     }
 
+    [Obsolete("Use GetOppositeTypeDefinition() instead. (Version 7.0.0)")]
     [JetBrains.Annotations.NotNull]
-    public static ClassDefinition GetOppositeClassDefinition (this IRelationEndPointDefinition relationEndPointDefinition)
+    public static TypeDefinition GetOppositeClassDefinition (this IRelationEndPointDefinition relationEndPointDefinition)
+    {
+      return relationEndPointDefinition.GetOppositeTypeDefinition();
+    }
+
+    [JetBrains.Annotations.NotNull]
+    public static TypeDefinition GetOppositeTypeDefinition (this IRelationEndPointDefinition relationEndPointDefinition)
     {
       ArgumentUtility.CheckNotNull("relationEndPointDefinition", relationEndPointDefinition);
-      return relationEndPointDefinition.GetOppositeEndPointDefinition().ClassDefinition;
+      return relationEndPointDefinition.GetOppositeEndPointDefinition().TypeDefinition;
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/SortExpressions/SortExpressionParser.cs b/Remotion/Data/DomainObjects/Mapping/SortExpressions/SortExpressionParser.cs
index dafdeb6c68..413c2bc656 100644
--- a/Remotion/Data/DomainObjects/Mapping/SortExpressions/SortExpressionParser.cs
+++ b/Remotion/Data/DomainObjects/Mapping/SortExpressions/SortExpressionParser.cs
@@ -27,13 +27,13 @@ namespace Remotion.Data.DomainObjects.Mapping.SortExpressions
   /// </summary>
   public class SortExpressionParser
   {
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
 
-    public SortExpressionParser (ClassDefinition classDefinition)
+    public SortExpressionParser (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      _classDefinition = classDefinition;
+      _typeDefinition = typeDefinition;
     }
 
     public SortExpressionDefinition? Parse (string sortExpression)
@@ -104,11 +104,13 @@ private PropertyDefinition ParsePropertyName (string fullOrShortPropertyName)
       // Try as full name first, only if that doesn't match, assume it must be a short name
       // If that still doesn't produce a match, search all derived classes for a full name match. Derived classes are not searched for short names.
       var propertyAccessorData =
-          _classDefinition.PropertyAccessorDataCache.GetPropertyAccessorData(fullOrShortPropertyName)
-          ?? _classDefinition.PropertyAccessorDataCache.FindPropertyAccessorData(_classDefinition.ClassType, fullOrShortPropertyName)
-          ?? GetAllDerivedClassDefinitions(_classDefinition)
-              .Select(cd => cd.PropertyAccessorDataCache.GetPropertyAccessorData(fullOrShortPropertyName))
-              .FirstOrDefault(data => data != null);
+          _typeDefinition.PropertyAccessorDataCache.GetPropertyAccessorData(fullOrShortPropertyName)
+          ?? _typeDefinition.PropertyAccessorDataCache.FindPropertyAccessorData(_typeDefinition.Type, fullOrShortPropertyName)
+          ?? InlineTypeDefinitionWalker.WalkDescendants(
+              _typeDefinition,
+              classDefinition => classDefinition.PropertyAccessorDataCache.GetPropertyAccessorData(fullOrShortPropertyName),
+              interfaceDefinition => throw new NotImplementedException("Interfaces are not supported."),
+              match: propertyAccessorData => propertyAccessorData != null); // TODO R2I Mapping: Add support for interfaces
 
       if (propertyAccessorData == null)
       {
@@ -117,7 +119,7 @@ private PropertyDefinition ParsePropertyName (string fullOrShortPropertyName)
             + "Alternatively, to resolve ambiguities or to use a property declared by a mixin or a derived class of '{1}', the full unique re-store "
             + "property identifier can be specified.",
             fullOrShortPropertyName,
-            _classDefinition.ClassType.Name);
+            _typeDefinition.Type.Name);
         throw new MappingException(message);
       }
 
@@ -134,11 +136,5 @@ private PropertyDefinition ParsePropertyName (string fullOrShortPropertyName)
 
       return propertyAccessorData.PropertyDefinition;
     }
-
-    private IEnumerable<ClassDefinition> GetAllDerivedClassDefinitions (ClassDefinition baseClassDefinition)
-    {
-      var directlyDerived = baseClassDefinition.DerivedClasses.Cast<ClassDefinition>();
-      return directlyDerived.Concat(directlyDerived.SelectMany(cd => GetAllDerivedClassDefinitions(cd)));
-    }
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/TypeDefinition.cs b/Remotion/Data/DomainObjects/Mapping/TypeDefinition.cs
new file mode 100644
index 0000000000..de872bfb32
--- /dev/null
+++ b/Remotion/Data/DomainObjects/Mapping/TypeDefinition.cs
@@ -0,0 +1,255 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using Remotion.Data.DomainObjects.Persistence.Model;
+using Remotion.Reflection;
+using Remotion.Utilities;
+
+namespace Remotion.Data.DomainObjects.Mapping
+{
+  public abstract class TypeDefinition
+  {
+    private readonly Lazy<RelationEndPointDefinitionCollection> _cachedRelationEndPointDefinitions;
+    private readonly Lazy<PropertyDefinitionCollection> _cachedPropertyDefinitions;
+
+    private PropertyDefinitionCollection? _propertyDefinitions;
+    private RelationEndPointDefinitionCollection? _relationEndPoints;
+    private IStorageEntityDefinition? _storageEntityDefinition;
+
+    public Type Type { get; }
+
+    public bool IsReadOnly { get; private set; }
+
+    public PropertyAccessorDataCache PropertyAccessorDataCache { get; }
+
+    public Type? StorageGroupType { get; }
+
+    public DefaultStorageClass DefaultStorageClass { get; }
+
+    protected TypeDefinition (Type type, Type? storageGroupType, DefaultStorageClass defaultStorageClass)
+    {
+      ArgumentUtility.CheckNotNull(nameof(type), type);
+
+      Type = type;
+      StorageGroupType = storageGroupType;
+      DefaultStorageClass = defaultStorageClass;
+
+      PropertyAccessorDataCache = new PropertyAccessorDataCache(this);
+      _cachedRelationEndPointDefinitions = new Lazy<RelationEndPointDefinitionCollection>(
+           CreateRelationEndPointDefinitionCollection,
+           LazyThreadSafetyMode.ExecutionAndPublication);
+      _cachedPropertyDefinitions =
+          new Lazy<PropertyDefinitionCollection>(
+              CreatePropertyDefinitionCollection,
+              LazyThreadSafetyMode.ExecutionAndPublication);
+    }
+
+    public abstract void Accept (ITypeDefinitionVisitor visitor);
+
+    public abstract T? Accept<T> (ITypeDefinitionVisitor<T> visitor);
+
+    public abstract bool IsPartOfInheritanceHierarchy { get; }
+
+    public abstract bool IsAssignableFrom (TypeDefinition other);
+
+    protected abstract void CheckPropertyDefinitions (IEnumerable<PropertyDefinition> propertyDefinitions);
+
+    protected abstract void CheckRelationEndPointDefinitions (IEnumerable<IRelationEndPointDefinition> relationEndPoints);
+
+    protected virtual PropertyDefinitionCollection CreatePropertyDefinitionCollection ()
+    {
+      return PropertyDefinitionCollection.CreateForAllProperties(this, true);
+    }
+
+    protected virtual RelationEndPointDefinitionCollection CreateRelationEndPointDefinitionCollection ()
+    {
+      return RelationEndPointDefinitionCollection.CreateForAllRelationEndPoints(this, true);
+    }
+
+    public IStorageEntityDefinition StorageEntityDefinition
+    {
+      get
+      {
+        if (_storageEntityDefinition == null)
+          throw new InvalidOperationException($"StorageEntityDefinition has not been set for type '{Type.GetFullNameSafe()}'.");
+
+        return _storageEntityDefinition;
+      }
+    }
+
+    public bool HasStorageEntityDefinitionBeenSet => _storageEntityDefinition != null;
+
+    public PropertyDefinitionCollection MyPropertyDefinitions
+    {
+      get
+      {
+        if (_propertyDefinitions == null)
+          throw new InvalidOperationException($"No property definitions have been set for type '{Type.GetFullNameSafe()}'.");
+
+        return _propertyDefinitions;
+      }
+    }
+
+    public RelationEndPointDefinitionCollection MyRelationEndPointDefinitions
+    {
+      get
+      {
+        if (_relationEndPoints == null)
+          throw new InvalidOperationException($"No relation end point definitions have been set for type '{Type.GetFullNameSafe()}'.");
+
+        return _relationEndPoints;
+      }
+    }
+
+    public virtual bool IsTypeResolved => true;
+
+    public PropertyDefinition? this [string propertyName]
+    {
+      get
+      {
+        ArgumentUtility.CheckNotNullOrEmpty(nameof(propertyName), propertyName);
+        return MyPropertyDefinitions[propertyName];
+      }
+    }
+
+    public void SetStorageEntity (IStorageEntityDefinition storageEntityDefinition)
+    {
+      ArgumentUtility.CheckNotNull(nameof(storageEntityDefinition), storageEntityDefinition);
+
+      if (IsReadOnly)
+        throw new NotSupportedException($"Type '{Type.GetFullNameSafe()}' is read-only.");
+
+      _storageEntityDefinition = storageEntityDefinition;
+    }
+
+    public PropertyDefinitionCollection GetPropertyDefinitions ()
+    {
+      return IsReadOnly
+          ? _cachedPropertyDefinitions.Value
+          : CreatePropertyDefinitionCollection();
+    }
+
+    public virtual PropertyDefinition? GetPropertyDefinition (string propertyName)
+    {
+      ArgumentUtility.CheckNotNullOrEmpty(nameof(propertyName), propertyName);
+
+      return GetPropertyDefinitions()[propertyName];
+    }
+
+    [Obsolete(
+        "Contains (...) method was ambiguous between GetPropertyDefinitions() and MyPropertyDefinitions. Use GetPropertyDefinitions().Contains (...) instead. (Version: 3.0.0)",
+        true)]
+    public bool Contains (PropertyDefinition propertyDefinition)
+    {
+      throw new NotSupportedException("Use GetPropertyDefinitions().Contains (...) instead. (Version: 3.0.0)");
+    }
+
+    public PropertyDefinition GetMandatoryPropertyDefinition (string propertyName)
+    {
+      ArgumentUtility.CheckNotNullOrEmpty("propertyName", propertyName);
+
+      var propertyDefinition = GetPropertyDefinition(propertyName);
+      if (propertyDefinition == null)
+        throw new MappingException($"Type '{Type.GetFullNameSafe()}' does not contain the property '{propertyName}'.");
+
+      return propertyDefinition;
+    }
+
+    public void SetPropertyDefinitions (PropertyDefinitionCollection propertyDefinitions)
+    {
+      ArgumentUtility.CheckNotNull(nameof(propertyDefinitions), propertyDefinitions);
+
+      if (IsReadOnly)
+        throw new NotSupportedException($"Type '{Type.GetFullNameSafe()}' is read-only.");
+
+      CheckPropertyDefinitions(propertyDefinitions);
+
+      _propertyDefinitions = propertyDefinitions;
+      _propertyDefinitions.SetReadOnly();
+    }
+
+    public RelationEndPointDefinitionCollection GetRelationEndPointDefinitions ()
+    {
+      return IsReadOnly
+        ? _cachedRelationEndPointDefinitions.Value
+        : CreateRelationEndPointDefinitionCollection();
+    }
+
+    public IRelationEndPointDefinition? GetRelationEndPointDefinition (string propertyName)
+    {
+      ArgumentUtility.CheckNotNullOrEmpty(nameof(propertyName), propertyName);
+
+      return GetRelationEndPointDefinitions()[propertyName];
+    }
+
+    public IRelationEndPointDefinition GetMandatoryRelationEndPointDefinition (string propertyName)
+    {
+      ArgumentUtility.CheckNotNullOrEmpty(nameof(propertyName), propertyName);
+
+      var relationEndPointDefinition = GetRelationEndPointDefinition(propertyName);
+      if (relationEndPointDefinition == null)
+        throw new MappingException($"No relation found for type '{Type.GetFullNameSafe()}' and property '{propertyName}'.");
+
+      return relationEndPointDefinition;
+    }
+
+    public void SetRelationEndPointDefinitions (RelationEndPointDefinitionCollection relationEndPoints)
+    {
+      ArgumentUtility.CheckNotNull(nameof(relationEndPoints), relationEndPoints);
+
+      if (IsReadOnly)
+        throw new NotSupportedException($"Type '{Type.GetFullNameSafe()}' is read-only.");
+
+      CheckRelationEndPointDefinitions(relationEndPoints);
+
+      _relationEndPoints = relationEndPoints;
+      _relationEndPoints.SetReadOnly();
+    }
+
+    public PropertyDefinition? ResolveProperty (IPropertyInformation propertyInformation)
+    {
+      ArgumentUtility.CheckNotNull(nameof(propertyInformation), propertyInformation);
+
+      var propertyAccessorData = PropertyAccessorDataCache.ResolvePropertyAccessorData(propertyInformation);
+      return propertyAccessorData?.PropertyDefinition;
+    }
+
+    public IRelationEndPointDefinition? ResolveRelationEndPoint (IPropertyInformation propertyInformation)
+    {
+      ArgumentUtility.CheckNotNull(nameof(propertyInformation), propertyInformation);
+
+      var propertyAccessorData = PropertyAccessorDataCache.ResolvePropertyAccessorData(propertyInformation);
+      return propertyAccessorData?.RelationEndPointDefinition;
+    }
+
+    public virtual void SetReadOnly ()
+    {
+      if (_storageEntityDefinition == null)
+        throw new InvalidOperationException("Cannot set the type definition read-only as the storage entity definition is not set.");
+      if (_propertyDefinitions == null)
+        throw new InvalidOperationException("Cannot set the type definition read-only as the property definitions are not set.");
+      if (_relationEndPoints == null)
+        throw new InvalidOperationException("Cannot set the type definition read-only as the relation endpoint definitions are not set.");
+
+      IsReadOnly = true;
+    }
+
+    public override string ToString () => $"{GetType().Name}: {Type.GetFullNameSafe()}";
+  }
+}
diff --git a/Remotion/Data/DomainObjects/Mapping/ClassDefinitionExtensions.cs b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionExtensions.cs
similarity index 62%
rename from Remotion/Data/DomainObjects/Mapping/ClassDefinitionExtensions.cs
rename to Remotion/Data/DomainObjects/Mapping/TypeDefinitionExtensions.cs
index 5d7df3e85c..ff1a599ed8 100644
--- a/Remotion/Data/DomainObjects/Mapping/ClassDefinitionExtensions.cs
+++ b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionExtensions.cs
@@ -20,19 +20,19 @@
 namespace Remotion.Data.DomainObjects.Mapping
 {
   /// <summary>
-  /// Provides extension methods for <see cref="ClassDefinition"/>.
+  /// Provides extension methods for <see cref="TypeDefinition"/>.
   /// </summary>
-  public static class ClassDefinitionExtensions
+  public static class TypeDefinitionExtensions
   {
     /// <summary>
-    /// Gets a flag if objects associated with the <see cref="ClassDefinition"/> are persistent or only held within the <see cref="ClientTransaction"/>.
+    /// Gets a flag if objects associated with the <see cref="TypeDefinition"/> are persistent or only held within the <see cref="ClientTransaction"/>.
     /// </summary>
-    /// <returns><see langword="true" /> if the <see cref="ClassDefinition.StorageEntityDefinition"/> is a <see cref="NonPersistentStorageEntity"/>.</returns>
-    internal static bool IsNonPersistent (this ClassDefinition classDefinition)
+    /// <returns><see langword="true" /> if the <see cref="TypeDefinition.StorageEntityDefinition"/> is a <see cref="NonPersistentStorageEntity"/>.</returns>
+    internal static bool IsNonPersistent (this TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return classDefinition.StorageEntityDefinition is NonPersistentStorageEntity;
+      return typeDefinition.StorageEntityDefinition is NonPersistentStorageEntity;
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/ClassDefinitionForUnresolvedRelationPropertyType.cs b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionForUnresolvedRelationPropertyType.cs
similarity index 50%
rename from Remotion/Data/DomainObjects/Mapping/ClassDefinitionForUnresolvedRelationPropertyType.cs
rename to Remotion/Data/DomainObjects/Mapping/TypeDefinitionForUnresolvedRelationPropertyType.cs
index 8e2f087112..98d319ec73 100644
--- a/Remotion/Data/DomainObjects/Mapping/ClassDefinitionForUnresolvedRelationPropertyType.cs
+++ b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionForUnresolvedRelationPropertyType.cs
@@ -15,26 +15,19 @@
 // along with re-motion; if not, see http://www.gnu.org/licenses.
 // 
 using System;
-using Remotion.Data.DomainObjects.Infrastructure;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using Remotion.Reflection;
 using Remotion.Utilities;
 
 namespace Remotion.Data.DomainObjects.Mapping
 {
-  public class ClassDefinitionForUnresolvedRelationPropertyType : ClassDefinition
+  public class TypeDefinitionForUnresolvedRelationPropertyType : TypeDefinition
   {
     private readonly IPropertyInformation _relationProperty;
 
-    public ClassDefinitionForUnresolvedRelationPropertyType (string id, Type classType, IPropertyInformation relationProperty)
-            : base(
-                    id,
-                    classType,
-                    false,
-                    null,
-                    null,
-                    DefaultStorageClass.Persistent,
-                    new PersistentMixinFinder(classType),
-                    new ThrowingDomainObjectCreator())
+    public TypeDefinitionForUnresolvedRelationPropertyType (Type type, IPropertyInformation relationProperty)
+            : base(type, null, DefaultStorageClass.Persistent)
     {
         ArgumentUtility.CheckNotNull("relationProperty", relationProperty);
 
@@ -46,9 +39,41 @@ public IPropertyInformation RelationProperty
       get { return _relationProperty; }
     }
 
-    public override bool IsClassTypeResolved
+    public override bool IsTypeResolved
     {
       get { return false; }
     }
+
+    public override bool IsPartOfInheritanceHierarchy
+    {
+      get { return false; }
+    }
+
+    public override bool IsAssignableFrom (TypeDefinition other)
+    {
+      return ReferenceEquals(this, other);
+    }
+
+    public override void Accept (ITypeDefinitionVisitor visitor)
+    {
+    }
+
+    [return: MaybeNull]
+    public override T Accept<T> (ITypeDefinitionVisitor<T> visitor)
+    {
+      return default;
+    }
+
+    protected override void CheckPropertyDefinitions (IEnumerable<PropertyDefinition> propertyDefinitions)
+    {
+    }
+
+    protected override void CheckRelationEndPointDefinitions (IEnumerable<IRelationEndPointDefinition> relationEndPoints)
+    {
+    }
+
+    protected override PropertyDefinitionCollection CreatePropertyDefinitionCollection () => new();
+
+    protected override RelationEndPointDefinitionCollection CreateRelationEndPointDefinitionCollection () => new();
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/TypeDefinitionHierarchy.cs b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionHierarchy.cs
new file mode 100644
index 0000000000..262f4d8607
--- /dev/null
+++ b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionHierarchy.cs
@@ -0,0 +1,153 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System.Collections.Generic;
+using Remotion.Utilities;
+
+namespace Remotion.Data.DomainObjects.Mapping
+{
+  /// <summary>
+  /// Provides methods for getting the hierarchy of a <see cref="TypeDefinition"/>.
+  /// </summary>
+  public static class TypeDefinitionHierarchy
+  {
+    /// <summary>
+    /// Checks if the two <see cref="TypeDefinition"/>s are part of the same hierarchy, sharing a common ascendant.
+    /// </summary>
+    public static bool ArePartOfSameHierarchy (TypeDefinition left, TypeDefinition right)
+    {
+      ArgumentUtility.CheckNotNull("left", left);
+      ArgumentUtility.CheckNotNull("right", right);
+
+      if (ReferenceEquals(left, right))
+        return true;
+
+      var typeHierarchyCollector = new TypeHierarchyCollector(TypeDefinitionWalkerDirection.Ascendants);
+      left.Accept(typeHierarchyCollector);
+
+      var leftTypeHierarchy = typeHierarchyCollector.ToHashSet();
+      return InlineTypeDefinitionWalker.WalkAncestors(
+          right,
+          classDefinition => leftTypeHierarchy.Contains(classDefinition),
+          interfaceDefinition => leftTypeHierarchy.Contains(interfaceDefinition),
+          match: result => result);
+    }
+
+    /// <summary>
+    /// Returns the hierarchy roots of the specified <paramref name="typeDefinitions"/>, using a depth-first approach.
+    /// </summary>
+    public static IReadOnlyList<TypeDefinition> GetHierarchyRoots (IEnumerable<TypeDefinition> typeDefinitions)
+    {
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
+
+      var inheritanceRootsCollector = new InheritanceRootsCollector();
+      foreach (var typeDefinition in typeDefinitions)
+      {
+        typeDefinition.Accept(inheritanceRootsCollector);
+      }
+
+      return inheritanceRootsCollector.ToArray();
+    }
+
+    /// <summary>
+    /// Returns the hierarchy (self and descendants) of the specified <paramref name="typeDefinition"/>, using a depth-first approach.
+    /// </summary>
+    /// <remarks>
+    /// The hierarchy includes the specified <paramref name="typeDefinition"/> as the first element.
+    /// </remarks>
+    public static IReadOnlyList<TypeDefinition> GetDescendantsAndSelf (TypeDefinition typeDefinition)
+    {
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
+
+      var typeHierarchyCollector = new TypeHierarchyCollector(TypeDefinitionWalkerDirection.Descendants);
+      typeDefinition.Accept(typeHierarchyCollector);
+
+      return typeHierarchyCollector.ToArray();
+    }
+
+    private class InheritanceRootsCollector : TypeDefinitionWalker
+    {
+      private readonly HashSet<TypeDefinition> _visitedTypeDefinitions = new();
+      private readonly List<TypeDefinition> _collectedTypeDefinitions = new();
+
+      public IReadOnlyList<TypeDefinition> ToArray () => _collectedTypeDefinitions.ToArray();
+
+      public InheritanceRootsCollector ()
+          : base(TypeDefinitionWalkerDirection.Ascendants)
+      {
+      }
+
+      /// <inheritdoc />
+      public override void VisitClassDefinition (ClassDefinition classDefinition)
+      {
+        if (!_visitedTypeDefinitions.Add(classDefinition))
+          return;
+
+        if (classDefinition.BaseClass == null)
+          _collectedTypeDefinitions.Add(classDefinition);
+
+        base.VisitClassDefinition(classDefinition);
+      }
+
+      /// <inheritdoc />
+      public override void VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition)
+      {
+        if (!_visitedTypeDefinitions.Add(interfaceDefinition))
+          return;
+
+        if (interfaceDefinition.ExtendedInterfaces.Count == 0)
+          _collectedTypeDefinitions.Add(interfaceDefinition);
+
+        base.VisitInterfaceDefinition(interfaceDefinition);
+      }
+    }
+
+    private class TypeHierarchyCollector : TypeDefinitionWalker
+    {
+      private readonly HashSet<TypeDefinition> _visitedTypeDefinitions = new();
+      private readonly List<TypeDefinition> _collectedTypeDefinitions = new();
+
+      public IReadOnlyList<TypeDefinition> ToArray () => _collectedTypeDefinitions.ToArray();
+
+      public HashSet<TypeDefinition> ToHashSet () => new(_collectedTypeDefinitions);
+
+      public TypeHierarchyCollector (TypeDefinitionWalkerDirection direction)
+          : base(direction)
+      {
+      }
+
+      /// <inheritdoc />
+      public override void VisitClassDefinition (ClassDefinition classDefinition)
+      {
+        if (!_visitedTypeDefinitions.Add(classDefinition))
+          return;
+
+        _collectedTypeDefinitions.Add(classDefinition);
+        base.VisitClassDefinition(classDefinition);
+      }
+
+      /// <inheritdoc />
+      public override void VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition)
+      {
+        if (!_visitedTypeDefinitions.Add(interfaceDefinition))
+          return;
+
+        _collectedTypeDefinitions.Add(interfaceDefinition);
+        base.VisitInterfaceDefinition(interfaceDefinition);
+      }
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects/Mapping/TypeDefinitionWalker.cs b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionWalker.cs
new file mode 100644
index 0000000000..306926f73a
--- /dev/null
+++ b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionWalker.cs
@@ -0,0 +1,74 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using Remotion.Utilities;
+
+namespace Remotion.Data.DomainObjects.Mapping
+{
+  /// <summary>
+  /// Implements a <see cref="ITypeDefinitionVisitor"/> that visits the type definitions in a depth-first manner.
+  /// The direction of the walk can be specified using <see cref="TypeDefinitionWalkerDirection"/>.
+  /// </summary>
+  public abstract class TypeDefinitionWalker : ITypeDefinitionVisitor
+  {
+    private readonly TypeDefinitionWalkerDirection _direction;
+
+    protected TypeDefinitionWalker (TypeDefinitionWalkerDirection direction)
+    {
+      _direction = direction;
+    }
+
+    /// <inheritdoc />
+    public virtual void VisitClassDefinition (ClassDefinition classDefinition)
+    {
+      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+
+      if (_direction == TypeDefinitionWalkerDirection.Descendants)
+      {
+        foreach (var derivedClass in classDefinition.DerivedClasses)
+          derivedClass.Accept(this);
+      }
+      else
+      {
+        if (classDefinition.BaseClass != null)
+          classDefinition.BaseClass.Accept(this);
+
+        foreach (var implementedInterface in classDefinition.ImplementedInterfaces)
+          implementedInterface.Accept(this);
+      }
+    }
+
+    /// <inheritdoc />
+    public virtual void VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition)
+    {
+      ArgumentUtility.CheckNotNull("interfaceDefinition", interfaceDefinition);
+
+      if (_direction == TypeDefinitionWalkerDirection.Descendants)
+      {
+        foreach (var implementingClass in interfaceDefinition.ImplementingClasses)
+          implementingClass.Accept(this);
+
+        foreach (var extendingInterface in interfaceDefinition.ExtendingInterfaces)
+          extendingInterface.Accept(this);
+      }
+      else
+      {
+        foreach (var extendedInterface in interfaceDefinition.ExtendedInterfaces)
+          extendedInterface.Accept(this);
+      }
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects/Mapping/TypeDefinitionWalker1.cs b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionWalker1.cs
new file mode 100644
index 0000000000..c8f8014644
--- /dev/null
+++ b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionWalker1.cs
@@ -0,0 +1,87 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+using System;
+using System.Linq;
+using Remotion.Utilities;
+
+namespace Remotion.Data.DomainObjects.Mapping
+{
+  /// <summary>
+  /// Implements a <see cref="ITypeDefinitionVisitor{T}"/> that visits the type definitions in a depth-first manner,
+  /// aborting the walk and returning the first value of <typeparamref name="T"/> that fulfills a specified predicate.
+  /// </summary>
+  public abstract class TypeDefinitionWalker<T> : ITypeDefinitionVisitor<T>
+  {
+    protected readonly TypeDefinitionWalkerDirection Direction;
+    protected readonly Func<T?, bool> Match;
+
+    protected TypeDefinitionWalker (TypeDefinitionWalkerDirection direction, Predicate<T?> match)
+    {
+      ArgumentUtility.CheckNotNull("match", match);
+
+      Direction = direction;
+      Match = new Func<T?, bool>(match);
+    }
+
+    /// <inheritdoc />
+    public virtual T? VisitClassDefinition (ClassDefinition classDefinition)
+    {
+      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+
+      if (Direction == TypeDefinitionWalkerDirection.Descendants)
+      {
+        return classDefinition.DerivedClasses
+            .Select(cd => cd.Accept(this))
+            .FirstOrDefault(Match);
+      }
+      else
+      {
+        if (classDefinition.BaseClass != null)
+        {
+          var result = classDefinition.BaseClass.Accept(this);
+          if (Match(result))
+            return result;
+        }
+
+        return classDefinition.ImplementedInterfaces
+            .Select(id => id.Accept(this))
+            .FirstOrDefault(Match);
+      }
+    }
+
+    /// <inheritdoc />
+    public virtual T? VisitInterfaceDefinition (InterfaceDefinition interfaceDefinition)
+    {
+      ArgumentUtility.CheckNotNull("interfaceDefinition", interfaceDefinition);
+
+      if (Direction == TypeDefinitionWalkerDirection.Descendants)
+      {
+        return interfaceDefinition.ImplementingClasses
+            .Cast<TypeDefinition>()
+            .Concat(interfaceDefinition.ExtendingInterfaces)
+            .Select(td => td.Accept(this))
+            .FirstOrDefault(Match);
+      }
+      else
+      {
+        return interfaceDefinition.ExtendedInterfaces
+            .Select(id => id.Accept(this))
+            .FirstOrDefault(Match);
+      }
+    }
+  }
+}
diff --git a/Remotion/Data/DomainObjects/Mapping/TypeDefinitionWalkerDirection.cs b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionWalkerDirection.cs
new file mode 100644
index 0000000000..6a130b81dc
--- /dev/null
+++ b/Remotion/Data/DomainObjects/Mapping/TypeDefinitionWalkerDirection.cs
@@ -0,0 +1,33 @@
+// This file is part of the re-motion Core Framework (www.re-motion.org)
+// Copyright (c) rubicon IT GmbH, www.rubicon.eu
+// 
+// The re-motion Core Framework is free software; you can redistribute it 
+// and/or modify it under the terms of the GNU Lesser General Public License 
+// as published by the Free Software Foundation; either version 2.1 of the 
+// License, or (at your option) any later version.
+// 
+// re-motion is distributed in the hope that it will be useful, 
+// but WITHOUT ANY WARRANTY; without even the implied warranty of 
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public License
+// along with re-motion; if not, see http://www.gnu.org/licenses.
+// 
+namespace Remotion.Data.DomainObjects.Mapping
+{
+  /// <summary>
+  /// Defines the direction a <see cref="TypeDefinitionWalker"/> can walk.
+  /// </summary>
+  public enum TypeDefinitionWalkerDirection
+  {
+    /// <summary>
+    /// The walker will walk upwards through all ascendants of the target <see cref="TypeDefinition"/>.
+    /// </summary>
+    Ascendants,
+    /// <summary>
+    /// The walker will walk downwards through all descendants of the target <see cref="TypeDefinition"/>.
+    /// </summary>
+    Descendants
+  }
+}
diff --git a/Remotion/Data/DomainObjects/Mapping/TypeNotCompatibleWithVirtualRelationEndPointDefinition.cs b/Remotion/Data/DomainObjects/Mapping/TypeNotCompatibleWithVirtualRelationEndPointDefinition.cs
index c649efed5a..ca4ce41da2 100644
--- a/Remotion/Data/DomainObjects/Mapping/TypeNotCompatibleWithVirtualRelationEndPointDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/TypeNotCompatibleWithVirtualRelationEndPointDefinition.cs
@@ -24,8 +24,8 @@ namespace Remotion.Data.DomainObjects.Mapping
   /// </summary>
   public class TypeNotCompatibleWithVirtualRelationEndPointDefinition : InvalidRelationEndPointDefinitionBase
   {
-    public TypeNotCompatibleWithVirtualRelationEndPointDefinition (ClassDefinition classDefinition, string propertyName, Type propertyType)
-        : base(classDefinition, propertyName, propertyType)
+    public TypeNotCompatibleWithVirtualRelationEndPointDefinition (TypeDefinition typeDefinition, string propertyName, Type propertyType)
+        : base(typeDefinition, propertyName, propertyType)
     {
     }
   }
diff --git a/Remotion/Data/DomainObjects/Mapping/TypeNotObjectIDRelationEndPointDefinition.cs b/Remotion/Data/DomainObjects/Mapping/TypeNotObjectIDRelationEndPointDefinition.cs
index 4788247aae..098e8c10ad 100644
--- a/Remotion/Data/DomainObjects/Mapping/TypeNotObjectIDRelationEndPointDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/TypeNotObjectIDRelationEndPointDefinition.cs
@@ -24,8 +24,8 @@ namespace Remotion.Data.DomainObjects.Mapping
   /// </summary>
   public class TypeNotObjectIDRelationEndPointDefinition : InvalidRelationEndPointDefinitionBase
   {
-    public TypeNotObjectIDRelationEndPointDefinition (ClassDefinition classDefinition, string propertyName, Type propertyType)
-        : base(classDefinition, propertyName, propertyType)
+    public TypeNotObjectIDRelationEndPointDefinition (TypeDefinition typeDefinition, string propertyName, Type propertyType)
+        : base(typeDefinition, propertyName, propertyType)
     {
     }
   }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/IPersistenceMappingValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/IPersistenceMappingValidationRule.cs
index 306be41da7..40bdaa907b 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/IPersistenceMappingValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/IPersistenceMappingValidationRule.cs
@@ -24,6 +24,6 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation
   /// </summary>
   public interface IPersistenceMappingValidationRule
   {
-    IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition);
+    IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/IPersistenceMappingValidator.cs b/Remotion/Data/DomainObjects/Mapping/Validation/IPersistenceMappingValidator.cs
index e108b6e329..4436b0e7fa 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/IPersistenceMappingValidator.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/IPersistenceMappingValidator.cs
@@ -24,6 +24,6 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation
   /// </summary>
   public interface IPersistenceMappingValidator
   {
-    IEnumerable<MappingValidationResult> Validate (IEnumerable<ClassDefinition> classDefinitions);
+    IEnumerable<MappingValidationResult> Validate (IEnumerable<TypeDefinition> typeDefinitions);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/IPropertyDefinitionValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/IPropertyDefinitionValidationRule.cs
index 20ebde0dec..2a8437f5b9 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/IPropertyDefinitionValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/IPropertyDefinitionValidationRule.cs
@@ -24,6 +24,6 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation
   /// </summary>
   public interface IPropertyDefinitionValidationRule
   {
-    IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition);
+    IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/IPropertyDefinitionValidator.cs b/Remotion/Data/DomainObjects/Mapping/Validation/IPropertyDefinitionValidator.cs
index 6e5979c3c3..0d52667b2a 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/IPropertyDefinitionValidator.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/IPropertyDefinitionValidator.cs
@@ -24,6 +24,6 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation
   /// </summary>
   public interface IPropertyDefinitionValidator
   {
-    IEnumerable<MappingValidationResult> Validate (IEnumerable<ClassDefinition> classDefinitions);
+    IEnumerable<MappingValidationResult> Validate (IEnumerable<TypeDefinition> typeDefinitions);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/IClassDefinitionValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/ITypeDefinitionValidationRule.cs
similarity index 82%
rename from Remotion/Data/DomainObjects/Mapping/Validation/IClassDefinitionValidationRule.cs
rename to Remotion/Data/DomainObjects/Mapping/Validation/ITypeDefinitionValidationRule.cs
index 0f237868a9..667813fea8 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/IClassDefinitionValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/ITypeDefinitionValidationRule.cs
@@ -19,10 +19,10 @@
 namespace Remotion.Data.DomainObjects.Mapping.Validation
 {
   /// <summary>
-  /// Defines the API for the class definition mapping validation rules.
+  /// Defines the API for the type definition mapping validation rules.
   /// </summary>
-  public interface IClassDefinitionValidationRule
+  public interface ITypeDefinitionValidationRule
   {
-    MappingValidationResult Validate (ClassDefinition classDefinition);
+    MappingValidationResult Validate (TypeDefinition typeDefinition);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/IClassDefinitionValidator.cs b/Remotion/Data/DomainObjects/Mapping/Validation/ITypeDefinitionValidator.cs
similarity index 82%
rename from Remotion/Data/DomainObjects/Mapping/Validation/IClassDefinitionValidator.cs
rename to Remotion/Data/DomainObjects/Mapping/Validation/ITypeDefinitionValidator.cs
index 46c6b74b4c..eecd8e3acf 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/IClassDefinitionValidator.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/ITypeDefinitionValidator.cs
@@ -20,10 +20,10 @@
 namespace Remotion.Data.DomainObjects.Mapping.Validation
 {
   /// <summary>
-  /// Defines the API for the class definition mapping validator.
+  /// Defines the API for the type definition mapping validator.
   /// </summary>
-  public interface IClassDefinitionValidator
+  public interface ITypeDefinitionValidator
   {
-    IEnumerable<MappingValidationResult> Validate (IEnumerable<ClassDefinition> classDefinitions);
+    IEnumerable<MappingValidationResult> Validate (IEnumerable<TypeDefinition> typeDefinitions);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForClassIDIsValidValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForClassIDIsValidValidationRule.cs
index fc8363e2a5..ec3b2f3ddb 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForClassIDIsValidValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForClassIDIsValidValidationRule.cs
@@ -21,9 +21,9 @@
 namespace Remotion.Data.DomainObjects.Mapping.Validation.Logical
 {
   /// <summary>
-  /// Validates that the given <see cref="ClassDefinition"/> has a valid class-ID containing only letters, digits, and underscores.
+  /// Validates that the given <see cref="TypeDefinition"/> has a valid class-ID containing only letters, digits, and underscores.
   /// </summary>
-  public class CheckForClassIDIsValidValidationRule : IClassDefinitionValidationRule
+  public class CheckForClassIDIsValidValidationRule : ITypeDefinitionValidationRule
   {
     private const string ClassIDPattern = @"^(?:\p{L}|_)(?:\p{L}|_|\p{N})*$";
     private static readonly Regex s_validClassID = new Regex(ClassIDPattern, RegexOptions.Compiled);
@@ -32,14 +32,17 @@ public CheckForClassIDIsValidValidationRule ()
     {
     }
 
-    public MappingValidationResult Validate (ClassDefinition classDefinition)
+    public MappingValidationResult Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
+
+      if (typeDefinition is not ClassDefinition classDefinition)
+        return MappingValidationResult.CreateValidResult();
 
       if (!s_validClassID.IsMatch(classDefinition.ID))
       {
         return MappingValidationResult.CreateInvalidResultForType(
-            classDefinition.ClassType,
+            typeDefinition.Type,
             "The Class-ID '{0}' is not valid. Valid Class-IDs must start with a letter or underscore and containing only letters, digits, and underscores.",
             classDefinition.ID);
       }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForInvalidRelationEndPointsValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForInvalidRelationEndPointsValidationRule.cs
index 482fce2c94..dcbadd76fa 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForInvalidRelationEndPointsValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForInvalidRelationEndPointsValidationRule.cs
@@ -33,18 +33,18 @@ public MappingValidationResult Validate (RelationDefinition relationDefinition)
         if (endPointDefinition is PropertyNotFoundRelationEndPointDefinition propertyNotFoundRelationEndPointDefinition)
         {
           return MappingValidationResult.CreateInvalidResultForType(
-              propertyNotFoundRelationEndPointDefinition.ClassDefinition.ClassType,
-              "Property '{0}' on class '{1}' could not be found.",
+              propertyNotFoundRelationEndPointDefinition.TypeDefinition.Type,
+              "Property '{0}' on type '{1}' could not be found.",
               propertyNotFoundRelationEndPointDefinition.PropertyName,
-              propertyNotFoundRelationEndPointDefinition.ClassDefinition.ClassType.Name);
+              propertyNotFoundRelationEndPointDefinition.TypeDefinition.Type.Name);
         }
         else if (endPointDefinition is TypeNotObjectIDRelationEndPointDefinition typeNotObjectIDRelationEndPointDefinition)
         {
           return MappingValidationResult.CreateInvalidResultForType(
-              typeNotObjectIDRelationEndPointDefinition.ClassDefinition.ClassType,
-            "Relation property '{0}' on class '{1}' is of type '{2}', but non-virtual relation properties must be of type '{3}'.",
+              typeNotObjectIDRelationEndPointDefinition.TypeDefinition.Type,
+            "Relation property '{0}' on type '{1}' is of type '{2}', but non-virtual relation properties must be of type '{3}'.",
             typeNotObjectIDRelationEndPointDefinition.PropertyName,
-            typeNotObjectIDRelationEndPointDefinition.ClassDefinition.ClassType.Name,
+            typeNotObjectIDRelationEndPointDefinition.TypeDefinition.Type.Name,
             typeNotObjectIDRelationEndPointDefinition.PropertyInfo.PropertyType.Name,
             typeof(ObjectID).Name);
         }
@@ -54,10 +54,10 @@ public MappingValidationResult Validate (RelationDefinition relationDefinition)
           Assertion.DebugIsNotNull(endPointDefinition.PropertyInfo, "endPointDefinition.PropertyInfo != null when endPointDefinition.IsAnonymous == false");
 
           return MappingValidationResult.CreateInvalidResultForType(
-              endPointDefinition.ClassDefinition.ClassType,
-              "Relation property '{0}' on class '{1}' is of type '{2}', but virtual relation properties must be of type '{3}', '{4}', or '{5}'.",
+              endPointDefinition.TypeDefinition.Type,
+              "Relation property '{0}' on type '{1}' is of type '{2}', but virtual relation properties must be of type '{3}', '{4}', or '{5}'.",
               endPointDefinition.PropertyName,
-              endPointDefinition.ClassDefinition.ClassType.Name,
+              endPointDefinition.TypeDefinition.Type.Name,
               endPointDefinition.PropertyInfo.PropertyType.Name,
               typeof(DomainObject).Name,
               typeof(ObjectList<>).Name,
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForTypeNotFoundClassDefinitionValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForTypeNotFoundTypeDefinitionValidationRule.cs
similarity index 67%
rename from Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForTypeNotFoundClassDefinitionValidationRule.cs
rename to Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForTypeNotFoundTypeDefinitionValidationRule.cs
index 43ee78011f..deaa7cb32d 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForTypeNotFoundClassDefinitionValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/CheckForTypeNotFoundTypeDefinitionValidationRule.cs
@@ -20,9 +20,9 @@
 namespace Remotion.Data.DomainObjects.Mapping.Validation.Logical
 {
   /// <summary>
-  /// Validates that the given<see cref="ClassDefinition"/> is no <see cref="ClassDefinitionForUnresolvedRelationPropertyType"/>.
+  /// Validates that the given<see cref="TypeDefinition"/> is no <see cref="TypeDefinitionForUnresolvedRelationPropertyType"/>.
   /// </summary>
-  public class CheckForTypeNotFoundClassDefinitionValidationRule : IRelationDefinitionValidatorRule
+  public class CheckForTypeNotFoundTypeDefinitionValidationRule : IRelationDefinitionValidatorRule
   {
     public MappingValidationResult Validate (RelationDefinition relationDefinition)
     {
@@ -30,15 +30,14 @@ public MappingValidationResult Validate (RelationDefinition relationDefinition)
 
       foreach (var endPointDefinition in relationDefinition.EndPointDefinitions)
       {
-        var classDefinitionAsTypeNotFoundClassDefinition = endPointDefinition.ClassDefinition as ClassDefinitionForUnresolvedRelationPropertyType;
-        if (classDefinitionAsTypeNotFoundClassDefinition!=null)
+        if (endPointDefinition.TypeDefinition is TypeDefinitionForUnresolvedRelationPropertyType unresolvedTypeDefinition)
         {
           return MappingValidationResult.CreateInvalidResultForProperty(
-              classDefinitionAsTypeNotFoundClassDefinition.RelationProperty,
+              unresolvedTypeDefinition.RelationProperty,
               "The relation property '{0}' has return type '{1}', which is not a part of the mapping. Relation properties must not point to "
-              + "classes above the inheritance root.",
-              classDefinitionAsTypeNotFoundClassDefinition.RelationProperty.Name,
-              classDefinitionAsTypeNotFoundClassDefinition.RelationProperty.PropertyType.Name);
+              + "types above the inheritance root.",
+              unresolvedTypeDefinition.RelationProperty.Name,
+              unresolvedTypeDefinition.RelationProperty.PropertyType.Name);
         }
       }
 
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/MandatoryExtensibleEnumTypeHasValuesDefinedValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/MandatoryExtensibleEnumTypeHasValuesDefinedValidationRule.cs
index 6655a3ad62..011423db12 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/MandatoryExtensibleEnumTypeHasValuesDefinedValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/MandatoryExtensibleEnumTypeHasValuesDefinedValidationRule.cs
@@ -31,11 +31,11 @@ public MandatoryExtensibleEnumTypeHasValuesDefinedValidationRule ()
     {
     }
 
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return from PropertyDefinition propertyDefinition in classDefinition.MyPropertyDefinitions
+      return from PropertyDefinition propertyDefinition in typeDefinition.MyPropertyDefinitions
           select Validate(propertyDefinition);
     }
 
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/MandatoryNetEnumTypeHasValuesDefinedValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/MandatoryNetEnumTypeHasValuesDefinedValidationRule.cs
index 6373c786be..3b486b1efa 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/MandatoryNetEnumTypeHasValuesDefinedValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/MandatoryNetEnumTypeHasValuesDefinedValidationRule.cs
@@ -30,11 +30,11 @@ public MandatoryNetEnumTypeHasValuesDefinedValidationRule ()
     {
     }
 
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return from PropertyDefinition propertyDefinition in classDefinition.MyPropertyDefinitions
+      return from PropertyDefinition propertyDefinition in typeDefinition.MyPropertyDefinitions
           select Validate(propertyDefinition);
     }
 
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/PropertyTypeIsSupportedValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/PropertyTypeIsSupportedValidationRule.cs
index 1a2c44bb0b..bec992a06a 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/PropertyTypeIsSupportedValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/PropertyTypeIsSupportedValidationRule.cs
@@ -31,11 +31,11 @@ public PropertyTypeIsSupportedValidationRule ()
     {
     }
 
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return from PropertyDefinition propertyDefinition in classDefinition.MyPropertyDefinitions
+      return from PropertyDefinition propertyDefinition in typeDefinition.MyPropertyDefinitions
              select Validate(propertyDefinition);
     }
 
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/RdbmsRelationEndPointCombinationIsSupportedValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/RdbmsRelationEndPointCombinationIsSupportedValidationRule.cs
index b971481dbc..4cdcacc5f4 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/RdbmsRelationEndPointCombinationIsSupportedValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/RdbmsRelationEndPointCombinationIsSupportedValidationRule.cs
@@ -81,9 +81,9 @@ public override MappingValidationResult Validate (RelationDefinition relationDef
             "The relation between property '{0}', declared on type '{1}', and property '{2}' declared on type '{3}', contains two virtual end points. "
             + "One of the two properties must set 'ContainsForeignKey' to 'true' on the '{4}'.",
             property1.Name,
-            endPointDefinition1.ClassDefinition.ClassType.Name,
+            endPointDefinition1.TypeDefinition.Type.Name,
             property2.Name,
-            endPointDefinition2.ClassDefinition.ClassType.Name,
+            endPointDefinition2.TypeDefinition.Type.Name,
             typeof(DBBidirectionalRelationAttribute).Name);
       }
 
@@ -95,9 +95,9 @@ public override MappingValidationResult Validate (RelationDefinition relationDef
             "The relation between property '{0}', declared on type '{1}', and property '{2}' declared on type '{3}', contains two non-virtual end points. "
             + "One of the two properties must set 'ContainsForeignKey' to 'false' on the '{4}'.",
             endPointDefinition1.PropertyInfo.Name,
-            endPointDefinition1.ClassDefinition.ClassType.Name,
+            endPointDefinition1.TypeDefinition.Type.Name,
             endPointDefinition2.PropertyInfo.Name,
-            endPointDefinition2.ClassDefinition.ClassType.Name,
+            endPointDefinition2.TypeDefinition.Type.Name,
             typeof(DBBidirectionalRelationAttribute).Name);
       }
 
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/SortExpressionIsSupportedForCardinalityOfRelationPropertyValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/SortExpressionIsSupportedForCardinalityOfRelationPropertyValidationRule.cs
index 985b751dfc..a3c66bb004 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/SortExpressionIsSupportedForCardinalityOfRelationPropertyValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/SortExpressionIsSupportedForCardinalityOfRelationPropertyValidationRule.cs
@@ -52,9 +52,9 @@ private MappingValidationResult Validate (IRelationEndPointDefinition relationEn
       {
         return MappingValidationResult.CreateInvalidResultForProperty(
             virtualObjectRelationEndPointDefinition.PropertyInfo,
-            "Property '{0}' of class '{1}' must not specify a SortExpression, because cardinality is equal to 'one'.",
+            "Property '{0}' of type '{1}' must not specify a SortExpression, because cardinality is equal to 'one'.",
             virtualObjectRelationEndPointDefinition.PropertyInfo.Name,
-            virtualObjectRelationEndPointDefinition.ClassDefinition.ClassType.Name);
+            virtualObjectRelationEndPointDefinition.TypeDefinition.Type.Name);
       }
       return MappingValidationResult.CreateValidResult();
     }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/StorageClassIsSupportedValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/StorageClassIsSupportedValidationRule.cs
index 6724a7186c..41f996c45a 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/StorageClassIsSupportedValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/StorageClassIsSupportedValidationRule.cs
@@ -32,11 +32,11 @@ public StorageClassIsSupportedValidationRule ()
     {
     }
 
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return from PropertyDefinition propertyDefinition in classDefinition.MyPropertyDefinitions
+      return from PropertyDefinition propertyDefinition in typeDefinition.MyPropertyDefinitions
              select Validate(propertyDefinition.PropertyInfo);
     }
 
@@ -51,7 +51,7 @@ private MappingValidationResult Validate (IPropertyInformation propertyInfo)
       {
         return MappingValidationResult.CreateInvalidResultForProperty(
             propertyInfo,
-            "Only StorageClass.Persistent and StorageClass.Transaction are supported for property '{0}' of class '{1}'.",
+            "Only StorageClass.Persistent and StorageClass.Transaction are supported for property '{0}' of type '{1}'.",
             propertyInfo.Name,
             propertyInfo.DeclaringType!.Name);
       }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/StorageGroupTypesAreSameWithinInheritanceTreeRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/StorageGroupTypesAreSameWithinInheritanceTreeRule.cs
index 8502badd42..663e6fb32b 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/StorageGroupTypesAreSameWithinInheritanceTreeRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/StorageGroupTypesAreSameWithinInheritanceTreeRule.cs
@@ -21,22 +21,26 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation.Logical
   /// <summary>
   /// Validates that the class has the same storage group type as its base class.
   /// </summary>
-  public class StorageGroupTypesAreSameWithinInheritanceTreeRule : IClassDefinitionValidationRule
+  public class StorageGroupTypesAreSameWithinInheritanceTreeRule : ITypeDefinitionValidationRule
   {
-    public MappingValidationResult Validate (ClassDefinition classDefinition)
+    public MappingValidationResult Validate (TypeDefinition typeDefinition)
     {
-      if (classDefinition.BaseClass != null)
+      if (typeDefinition is not ClassDefinition classDefinition)
+        throw new InvalidOperationException("Only class definitions are supported"); // TODO R2I Validation: Support interfaces as well
+
+      if (classDefinition.BaseClass == null)
+        return MappingValidationResult.CreateValidResult();
+
+      if (classDefinition.StorageGroupType != classDefinition.BaseClass.StorageGroupType)
       {
-        if (classDefinition.StorageGroupType != classDefinition.BaseClass.StorageGroupType)
-        {
-          var message = "Class '{0}' must have the same storage group type as its base class '{1}'.";
-          return MappingValidationResult.CreateInvalidResultForType(
-              classDefinition.ClassType,
-              message,
-              classDefinition.ClassType.Name,
-              classDefinition.BaseClass.ClassType.Name);
-        }
+        var message = "Class '{0}' must have the same storage group type as its base class '{1}'.";
+        return MappingValidationResult.CreateInvalidResultForType(
+            classDefinition.Type,
+            message,
+            classDefinition.Type.Name,
+            classDefinition.BaseClass.Type.Name);
       }
+
       return MappingValidationResult.CreateValidResult();
     }
   }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/VirtualRelationEndPointPropertyTypeIsSupportedValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/VirtualRelationEndPointPropertyTypeIsSupportedValidationRule.cs
index a53bf3abea..d93deaa0ce 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Logical/VirtualRelationEndPointPropertyTypeIsSupportedValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Logical/VirtualRelationEndPointPropertyTypeIsSupportedValidationRule.cs
@@ -53,9 +53,9 @@ private MappingValidationResult Validate (IRelationEndPointDefinition relationEn
       {
         return MappingValidationResult.CreateInvalidResultForProperty(
             relationEndPointDefinition.PropertyInfo,
-            "Virtual property '{0}' of class '{1}' is of type '{2}', but must be assignable to '{3}' or '{4}' or be of type '{5}'.",
+            "Virtual property '{0}' of type '{1}' is of type '{2}', but must be assignable to '{3}' or '{4}' or be of type '{5}'.",
             relationEndPointDefinition.PropertyInfo.Name,
-            relationEndPointDefinition.ClassDefinition.ClassType.Name,
+            relationEndPointDefinition.TypeDefinition.Type.Name,
             relationEndPointDefinition.PropertyInfo.PropertyType.Name,
             typeof(DomainObject).Name,
             typeof(ObjectList<>).Name,
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/PersistenceMappingValidator.cs b/Remotion/Data/DomainObjects/Mapping/Validation/PersistenceMappingValidator.cs
index d93fd5c032..10bc2300d7 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/PersistenceMappingValidator.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/PersistenceMappingValidator.cs
@@ -43,13 +43,13 @@ public ReadOnlyCollection<IPersistenceMappingValidationRule> ValidationRules
       get { return _validationRules; }
     }
 
-    public IEnumerable<MappingValidationResult> Validate (IEnumerable<ClassDefinition> classDefinitions)
+    public IEnumerable<MappingValidationResult> Validate (IEnumerable<TypeDefinition> typeDefinitions)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
       return from rule in _validationRules
-             from classDefinition in classDefinitions
-             from result in rule.Validate(classDefinition)
+             from typeDefinition in typeDefinitions
+             from result in rule.Validate(typeDefinition)
              where !result.IsValid
              select result;
     }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/PropertyDefinitionValidator.cs b/Remotion/Data/DomainObjects/Mapping/Validation/PropertyDefinitionValidator.cs
index 47e60da772..b9b3aae0ef 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/PropertyDefinitionValidator.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/PropertyDefinitionValidator.cs
@@ -43,13 +43,13 @@ public ReadOnlyCollection<IPropertyDefinitionValidationRule> ValidationRules
       get { return _validationRules; }
     }
 
-    public IEnumerable<MappingValidationResult> Validate (IEnumerable<ClassDefinition> classDefinitions)
+    public IEnumerable<MappingValidationResult> Validate (IEnumerable<TypeDefinition> typeDefinitions)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
       return from rule in _validationRules
-             from classDefinition in classDefinitions
-             from result in rule.Validate(classDefinition)
+             from typeDefinition in typeDefinitions
+             from result in rule.Validate(typeDefinition)
              where !result.IsValid
              select result;
     }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/ClassDefinitionTypeIsSubclassOfDomainObjectValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/ClassDefinitionTypeIsSubclassOfDomainObjectValidationRule.cs
index 71630ad991..a037c4f6c4 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/ClassDefinitionTypeIsSubclassOfDomainObjectValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/ClassDefinitionTypeIsSubclassOfDomainObjectValidationRule.cs
@@ -22,18 +22,21 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation.Reflection
   /// <summary>
   /// Validates that a class definition type is a sub-class of domain object. 
   /// </summary>
-  public class ClassDefinitionTypeIsSubclassOfDomainObjectValidationRule : IClassDefinitionValidationRule
+  public class ClassDefinitionTypeIsSubclassOfDomainObjectValidationRule : ITypeDefinitionValidationRule
   {
-    public MappingValidationResult Validate (ClassDefinition classDefinition)
+    public MappingValidationResult Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      if (!ReflectionUtility.IsDomainObject(classDefinition.ClassType))
+      if (typeDefinition is not ClassDefinition classDefinition) // TODO R2I Validation: for interface support
+        throw new InvalidOperationException("Only class definitions are supported.");
+
+      if (!ReflectionUtility.IsDomainObject(classDefinition.Type))
       {
         return MappingValidationResult.CreateInvalidResultForType(
-            classDefinition.ClassType,
+            classDefinition.Type,
             "Type '{0}' of class '{1}' is not assignable to '{2}'.",
-            classDefinition.ClassType.Name,
+            classDefinition.Type.Name,
             classDefinition.ID,
             typeof(DomainObject).Name);
       }
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRule.cs
index 9913488aae..d8715a8542 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRule.cs
@@ -24,18 +24,18 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation.Reflection
   /// <summary>
   /// Validates that the domain object does not have a legacy infrastructure constructor taking a single data container argument.
   /// </summary>
-  public class DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRule : IClassDefinitionValidationRule
+  public class DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRule : ITypeDefinitionValidationRule
   {
     public DomainObjectTypeDoesNotHaveLegacyInfrastructureConstructorValidationRule ()
     {
 
     }
 
-    public MappingValidationResult Validate (ClassDefinition classDefinition)
+    public MappingValidationResult Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return Validate(classDefinition.ClassType);
+      return Validate(typeDefinition.Type);
     }
 
     private MappingValidationResult Validate (Type type)
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/DomainObjectTypeIsNotGenericValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/DomainObjectTypeIsNotGenericValidationRule.cs
index c79bb1eb4b..c74e959bde 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/DomainObjectTypeIsNotGenericValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/DomainObjectTypeIsNotGenericValidationRule.cs
@@ -22,18 +22,18 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation.Reflection
   /// <summary>
   /// Validates that a class definition type is not generic.
   /// </summary>
-  public class DomainObjectTypeIsNotGenericValidationRule : IClassDefinitionValidationRule
+  public class DomainObjectTypeIsNotGenericValidationRule : ITypeDefinitionValidationRule
   {
     public DomainObjectTypeIsNotGenericValidationRule ()
     {
 
     }
 
-    public MappingValidationResult Validate (ClassDefinition classDefinition)
+    public MappingValidationResult Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return Validate(classDefinition.ClassType);
+      return Validate(typeDefinition.Type);
     }
 
     private MappingValidationResult Validate (Type type)
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/InheritanceHierarchyFollowsClassHierarchyValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/InheritanceHierarchyFollowsClassHierarchyValidationRule.cs
index aa2efeecf8..acf84c16d6 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/InheritanceHierarchyFollowsClassHierarchyValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/InheritanceHierarchyFollowsClassHierarchyValidationRule.cs
@@ -22,23 +22,29 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation.Reflection
   /// <summary>
   /// Validates that the type of a class defintion is derived from base type.
   /// </summary>
-  public class InheritanceHierarchyFollowsClassHierarchyValidationRule : IClassDefinitionValidationRule
+  public class InheritanceHierarchyFollowsClassHierarchyValidationRule : ITypeDefinitionValidationRule
   {
     public InheritanceHierarchyFollowsClassHierarchyValidationRule ()
     {
 
     }
 
-    public MappingValidationResult Validate (ClassDefinition classDefinition)
+    public MappingValidationResult Validate (TypeDefinition typeDefinition)
     {
-      if (classDefinition.BaseClass !=null && !classDefinition.ClassType.IsSubclassOf(classDefinition.BaseClass.ClassType))
+      if (typeDefinition is not ClassDefinition classDefinition) // TODO R2I Valdiation: Support for interface support
+        throw new InvalidOperationException("Only class definitions are supported.");
+
+      if (classDefinition.BaseClass == null)
+        return MappingValidationResult.CreateValidResult();
+
+      if (!classDefinition.Type.IsSubclassOf(classDefinition.BaseClass.Type))
       {
         return MappingValidationResult.CreateInvalidResultForType(
-            classDefinition.BaseClass.ClassType,
+            classDefinition.BaseClass.Type,
             "Type '{0}' of class '{1}' is not derived from type '{2}' of base class '{3}'.",
-            classDefinition.ClassType.GetAssemblyQualifiedNameSafe(),
+            classDefinition.Type.GetAssemblyQualifiedNameSafe(),
             classDefinition.ID,
-            classDefinition.BaseClass.ClassType.GetAssemblyQualifiedNameSafe(),
+            classDefinition.BaseClass.Type.GetAssemblyQualifiedNameSafe(),
             classDefinition.BaseClass.ID);
       }
       return MappingValidationResult.CreateValidResult();
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/MappingAttributesAreOnlyAppliedOnOriginalPropertyDeclarationsValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/MappingAttributesAreOnlyAppliedOnOriginalPropertyDeclarationsValidationRule.cs
index 4badaf0218..774ba994ce 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/MappingAttributesAreOnlyAppliedOnOriginalPropertyDeclarationsValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/MappingAttributesAreOnlyAppliedOnOriginalPropertyDeclarationsValidationRule.cs
@@ -42,21 +42,29 @@ public MappingAttributesAreOnlyAppliedOnOriginalPropertyDeclarationsValidationRu
       _propertyMetadataProvider = propertyMetadataProvider;
     }
 
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      if (!classDefinition.IsClassTypeResolved)
-        throw new InvalidOperationException("Class type of '" + classDefinition.ID + "' is not resolved.");
+      if (!typeDefinition.IsTypeResolved)
+        throw new InvalidOperationException("Type '" + typeDefinition.Type.GetFullNameSafe() + "' is not resolved.");
 
-      bool isInheritanceRoot = classDefinition.BaseClass == null;
-      var propertyFinder = new AllMappingPropertiesFinder(
-          classDefinition.ClassType,
-          isInheritanceRoot,
-          true,
-          _nameResolver,
-          classDefinition.PersistentMixinFinder,
-          _propertyMetadataProvider);
+      AllMappingPropertiesFinder propertyFinder;
+      if (typeDefinition is ClassDefinition classDefinition)
+      {
+        var isInheritanceRoot = classDefinition.BaseClass == null;
+        propertyFinder = new AllMappingPropertiesFinder(
+            classDefinition.Type,
+            isInheritanceRoot,
+            true,
+            _nameResolver,
+            classDefinition.PersistentMixinFinder,
+            _propertyMetadataProvider);
+      }
+      else
+      {
+        throw new NotSupportedException("Only class definitions are supported."); // TODO R2I Mapping: property finder support for interfaces
+      }
       var propertyInfos = propertyFinder.FindPropertyInfos();
 
       return from IPropertyInformation propertyInfo in propertyInfos
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/MappingAttributesAreSupportedForPropertyTypeValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/MappingAttributesAreSupportedForPropertyTypeValidationRule.cs
index 065a61d717..8f88a791d5 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/MappingAttributesAreSupportedForPropertyTypeValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/MappingAttributesAreSupportedForPropertyTypeValidationRule.cs
@@ -72,11 +72,11 @@ public MappingAttributesAreSupportedForPropertyTypeValidationRule ()
     {
     }
 
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return from PropertyDefinition propertyDefinition in classDefinition.MyPropertyDefinitions
+      return from PropertyDefinition propertyDefinition in typeDefinition.MyPropertyDefinitions
              select Validate(propertyDefinition.PropertyInfo);
     }
 
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/RelationEndPointTypesAreConsistentValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/RelationEndPointTypesAreConsistentValidationRule.cs
index 30807d2748..42f56d0c2c 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/RelationEndPointTypesAreConsistentValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/RelationEndPointTypesAreConsistentValidationRule.cs
@@ -53,16 +53,16 @@ private MappingValidationResult Validate (IRelationEndPointDefinition relationEn
             && relationAttribute != null)
         {
           var oppositePropertyInfo = oppositeEndPointDefinition.PropertyInfo;
-          var classDefinition = relationEndPointDefinition.ClassDefinition;
+          var typeDefinition = relationEndPointDefinition.TypeDefinition;
           var oppositeDomainObjectType = ReflectionUtility.GetRelatedObjectTypeFromRelationProperty(oppositePropertyInfo);
           var declaringDomainObjectTypeForProperty =
-              ReflectionUtility.GetDeclaringDomainObjectTypeForProperty(relationEndPointDefinition.PropertyInfo, classDefinition);
-          bool isPropertyDeclaredByThisClassDefinition = declaringDomainObjectTypeForProperty == classDefinition.ClassType;
-          if (isPropertyDeclaredByThisClassDefinition)
+              ReflectionUtility.GetDeclaringDomainObjectTypeForProperty(relationEndPointDefinition.PropertyInfo, typeDefinition);
+          bool isPropertyDeclaredByThisTypeDefinition = declaringDomainObjectTypeForProperty == typeDefinition.Type;
+          if (isPropertyDeclaredByThisTypeDefinition)
           {
-            // Case where property is declared on this ClassDefinition => it is declared below/on the inheritance root
-            // In this case, the opposite property's return type must exactly match this ClassDefinition's type.
-            if (classDefinition.ClassType != oppositeDomainObjectType)
+            // Case where property is declared on this TypeDefinition => it is declared below/on the inheritance root
+            // In this case, the opposite property's return type must exactly match this TypeDefinition's type.
+            if (typeDefinition.Type != oppositeDomainObjectType)
             {
               return MappingValidationResult.CreateInvalidResultForProperty(
                   relationEndPointDefinition.PropertyInfo,
@@ -74,7 +74,7 @@ private MappingValidationResult Validate (IRelationEndPointDefinition relationEn
           }
           else
           {
-            // Case where property is not declared on this ClassDefinition => it must be declared above the inheritance root
+            // Case where property is not declared on this TypeDefinition => it must be declared above the inheritance root
             // In this case, the opposite property's return type must be assignable to the type declaring the property. This enables the following 
             // scenario:
             // - ClassAboveInheritanceRoot has a relation property P1 to RelationTarget
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/StorageGroupAttributeIsOnlyDefinedOncePerInheritanceHierarchyValidationRule.cs b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/StorageGroupAttributeIsOnlyDefinedOncePerInheritanceHierarchyValidationRule.cs
index 48e67564a6..403e3e63a8 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/StorageGroupAttributeIsOnlyDefinedOncePerInheritanceHierarchyValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/Reflection/StorageGroupAttributeIsOnlyDefinedOncePerInheritanceHierarchyValidationRule.cs
@@ -22,17 +22,17 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation.Reflection
   /// <summary>
   /// Validates that the StorageGroupAttribute is not defined twice in the class hierarchy.
   /// </summary>
-  public class StorageGroupAttributeIsOnlyDefinedOncePerInheritanceHierarchyValidationRule : IClassDefinitionValidationRule
+  public class StorageGroupAttributeIsOnlyDefinedOncePerInheritanceHierarchyValidationRule : ITypeDefinitionValidationRule
   {
     public StorageGroupAttributeIsOnlyDefinedOncePerInheritanceHierarchyValidationRule ()
     {
     }
 
-    public MappingValidationResult Validate (ClassDefinition classDefinition)
+    public MappingValidationResult Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return Validate(classDefinition.ClassType);
+      return Validate(typeDefinition.Type); // TODO R2I Validation: Support for interfaces
     }
 
     private MappingValidationResult Validate (Type type)
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/SortExpressionValidator.cs b/Remotion/Data/DomainObjects/Mapping/Validation/SortExpressionValidator.cs
index ac255ba911..55fab5976d 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/SortExpressionValidator.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/SortExpressionValidator.cs
@@ -25,7 +25,7 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation
 {
   /// <summary>
   /// The <see cref="SortExpressionValidator"/> validates the sort expression text of the <see cref="DBBidirectionalRelationAttribute"/> 
-  /// on the <see cref="PropertyInfo"/> of the <see cref="ClassDefinition"/>s.
+  /// on the <see cref="PropertyInfo"/> of the <see cref="TypeDefinition"/>s.
   /// </summary>
   public class SortExpressionValidator : ISortExpressionValidator
   {
diff --git a/Remotion/Data/DomainObjects/Mapping/Validation/ClassDefinitionValidator.cs b/Remotion/Data/DomainObjects/Mapping/Validation/TypeDefinitionValidator.cs
similarity index 78%
rename from Remotion/Data/DomainObjects/Mapping/Validation/ClassDefinitionValidator.cs
rename to Remotion/Data/DomainObjects/Mapping/Validation/TypeDefinitionValidator.cs
index 516dc6b0f0..d9c07d5b80 100644
--- a/Remotion/Data/DomainObjects/Mapping/Validation/ClassDefinitionValidator.cs
+++ b/Remotion/Data/DomainObjects/Mapping/Validation/TypeDefinitionValidator.cs
@@ -27,28 +27,28 @@ namespace Remotion.Data.DomainObjects.Mapping.Validation
   /// class definitions to validate. Each validation rule is applied to each class definition and for every rule which is invalid a 
   /// mapping validation result with the respective error message is returned.
   /// </summary>
-  public class ClassDefinitionValidator : IClassDefinitionValidator
+  public class TypeDefinitionValidator : ITypeDefinitionValidator
   {
-    private readonly ReadOnlyCollection<IClassDefinitionValidationRule> _validationRules;
+    private readonly ReadOnlyCollection<ITypeDefinitionValidationRule> _validationRules;
 
-    public ClassDefinitionValidator (params IClassDefinitionValidationRule[] validationRules)
+    public TypeDefinitionValidator (params ITypeDefinitionValidationRule[] validationRules)
     {
       ArgumentUtility.CheckNotNull("validationRules", validationRules);
 
       _validationRules = Array.AsReadOnly(validationRules);
     }
 
-    public ReadOnlyCollection<IClassDefinitionValidationRule> ValidationRules
+    public ReadOnlyCollection<ITypeDefinitionValidationRule> ValidationRules
     {
       get { return _validationRules; }
     }
 
-    public IEnumerable<MappingValidationResult> Validate (IEnumerable<ClassDefinition> classDefinitions)
+    public IEnumerable<MappingValidationResult> Validate (IEnumerable<TypeDefinition> typeDefinitions)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
       return from r in _validationRules
-             from c in classDefinitions
+             from c in typeDefinitions
              let result = r.Validate(c)
              where !result.IsValid
              select result;
diff --git a/Remotion/Data/DomainObjects/Mapping/VirtualCollectionRelationEndPointDefinition.cs b/Remotion/Data/DomainObjects/Mapping/VirtualCollectionRelationEndPointDefinition.cs
index 9524fb58ef..543663b062 100644
--- a/Remotion/Data/DomainObjects/Mapping/VirtualCollectionRelationEndPointDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/VirtualCollectionRelationEndPointDefinition.cs
@@ -31,24 +31,24 @@ public class VirtualCollectionRelationEndPointDefinition : IRelationEndPointDefi
   {
     private readonly string _propertyName;
     private RelationDefinition? _relationDefinition;
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
     private readonly bool _isMandatory;
     private readonly Lazy<SortExpressionDefinition?> _sortExpression;
     private readonly IPropertyInformation _propertyInfo;
 
     public VirtualCollectionRelationEndPointDefinition (
-        [NotNull] ClassDefinition classDefinition,
+        [NotNull] TypeDefinition typeDefinition,
         string propertyName,
         bool isMandatory,
         [NotNull] Lazy<SortExpressionDefinition?> sortExpression,
         [NotNull] IPropertyInformation propertyInfo)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNullOrEmpty("propertyName", propertyName);
       ArgumentUtility.CheckNotNull("sortExpression", sortExpression);
       ArgumentUtility.CheckNotNull("propertyInfo", propertyInfo);
 
-      _classDefinition = classDefinition;
+      _typeDefinition = typeDefinition;
       _isMandatory = isMandatory;
       _propertyName = propertyName;
       _sortExpression = sortExpression;
@@ -75,9 +75,9 @@ public RelationDefinition RelationDefinition
       }
     }
 
-    public ClassDefinition ClassDefinition
+    public TypeDefinition TypeDefinition
     {
-      get { return _classDefinition; }
+      get { return _typeDefinition; }
     }
 
     public bool IsMandatory
diff --git a/Remotion/Data/DomainObjects/Mapping/VirtualObjectRelationEndPointDefinition.cs b/Remotion/Data/DomainObjects/Mapping/VirtualObjectRelationEndPointDefinition.cs
index a88dbc576e..0859abd53a 100644
--- a/Remotion/Data/DomainObjects/Mapping/VirtualObjectRelationEndPointDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/VirtualObjectRelationEndPointDefinition.cs
@@ -29,22 +29,22 @@ public class VirtualObjectRelationEndPointDefinition : IRelationEndPointDefiniti
   {
     private readonly string _propertyName;
     private RelationDefinition? _relationDefinition;
-    private readonly ClassDefinition _classDefinition;
+    private readonly TypeDefinition _typeDefinition;
     private readonly bool _isMandatory;
     private readonly IPropertyInformation _propertyInfo;
     private bool _hasSortExpression;
 
     public VirtualObjectRelationEndPointDefinition (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         bool isMandatory,
         IPropertyInformation propertyInfo)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
       ArgumentUtility.CheckNotNullOrEmpty("propertyName", propertyName);
       ArgumentUtility.CheckNotNull("propertyInfo", propertyInfo);
 
-      _classDefinition = classDefinition;
+      _typeDefinition = typeDefinition;
       _isMandatory = isMandatory;
       _propertyName = propertyName;
       _propertyInfo = propertyInfo;
@@ -70,9 +70,9 @@ public RelationDefinition RelationDefinition
       }
     }
 
-    public ClassDefinition ClassDefinition
+    public TypeDefinition TypeDefinition
     {
-      get { return _classDefinition; }
+      get { return _typeDefinition; }
     }
 
     public bool IsMandatory
diff --git a/Remotion/Data/DomainObjects/Mapping/VirtualRelationEndPointDefinition.cs b/Remotion/Data/DomainObjects/Mapping/VirtualRelationEndPointDefinition.cs
index 6776f13bc3..60fd398bc6 100644
--- a/Remotion/Data/DomainObjects/Mapping/VirtualRelationEndPointDefinition.cs
+++ b/Remotion/Data/DomainObjects/Mapping/VirtualRelationEndPointDefinition.cs
@@ -26,7 +26,7 @@ namespace Remotion.Data.DomainObjects.Mapping
   public class VirtualRelationEndPointDefinition : IRelationEndPointDefinition
   {
     public VirtualRelationEndPointDefinition (
-        ClassDefinition classDefinition,
+        TypeDefinition typeDefinition,
         string propertyName,
         bool isMandatory,
         CardinalityType cardinality,
@@ -39,7 +39,7 @@ public VirtualRelationEndPointDefinition (
 
     public RelationDefinition RelationDefinition => null!;
 
-    public ClassDefinition ClassDefinition => null!;
+    public TypeDefinition TypeDefinition => null!;
 
     public bool IsMandatory => false;
 
diff --git a/Remotion/Data/DomainObjects/ObjectID.cs b/Remotion/Data/DomainObjects/ObjectID.cs
index 9a03e2341b..7d03b5ab08 100644
--- a/Remotion/Data/DomainObjects/ObjectID.cs
+++ b/Remotion/Data/DomainObjects/ObjectID.cs
@@ -167,7 +167,7 @@ public ObjectID (string classID, object value)
     /// </exception>
     /// <exception cref="Mapping.MappingException"/>The specified <paramref name="classType"/> could not be found in the mapping configuration.
     public ObjectID (Type classType, object value)
-      : this(MappingConfiguration.Current.GetTypeDefinition(ArgumentUtility.CheckNotNull("classType", classType)), value)
+      : this(MappingConfiguration.Current.GetClassDefinition(ArgumentUtility.CheckNotNull("classType", classType)), value)
     {
     }
 
@@ -200,7 +200,7 @@ public ObjectID (ClassDefinition classDefinition, object value)
         throw CreateArgumentException(
             "classDefinition",
             "An ObjectID cannot be constructed for abstract type '{0}' of class '{1}'.",
-            classDefinition.ClassType.GetAssemblyQualifiedNameSafe(),
+            classDefinition.Type.GetAssemblyQualifiedNameSafe(),
             classDefinition.ID);
       }
 
@@ -250,7 +250,7 @@ public ClassDefinition ClassDefinition
     /// <summary>
     /// Creates a typed handle to the <see cref="DomainObject"/> identified by this <see cref="ObjectID"/>.
     /// </summary>
-    /// <typeparam name="T">The handle's object type. This must either be the <see cref="Mapping.ClassDefinition.ClassType"/> of this 
+    /// <typeparam name="T">The handle's object type. This must either be the <see cref="TypeDefinition.Type"/> of this 
     /// <see cref="ObjectID"/>, or a base type of it.</typeparam>
     /// <returns>A typed handle to the <see cref="DomainObject"/> identified by this <see cref="ObjectID"/>.</returns>
     public IDomainObjectHandle<T> GetHandle<T> () where T : IDomainObject
diff --git a/Remotion/Data/DomainObjects/Persistence/Configuration/DeferredStorageSettings.cs b/Remotion/Data/DomainObjects/Persistence/Configuration/DeferredStorageSettings.cs
index 8310fe228c..0504305e94 100644
--- a/Remotion/Data/DomainObjects/Persistence/Configuration/DeferredStorageSettings.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Configuration/DeferredStorageSettings.cs
@@ -64,11 +64,11 @@ public DeferredStorageSettings (IStorageObjectFactoryFactory storageObjectFactor
           LazyThreadSafetyMode.ExecutionAndPublication);
     }
 
-    public StorageProviderDefinition GetStorageProviderDefinition (ClassDefinition classDefinition)
+    public StorageProviderDefinition GetStorageProviderDefinition (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return _storageSettings.Value.GetStorageProviderDefinition(classDefinition);
+      return _storageSettings.Value.GetStorageProviderDefinition(typeDefinition);
     }
 
     public StorageProviderDefinition GetStorageProviderDefinition (Type? storageGroupTypeOrNull)
diff --git a/Remotion/Data/DomainObjects/Persistence/Configuration/IStorageSettings.cs b/Remotion/Data/DomainObjects/Persistence/Configuration/IStorageSettings.cs
index 9117b7c9f4..214644be0b 100644
--- a/Remotion/Data/DomainObjects/Persistence/Configuration/IStorageSettings.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Configuration/IStorageSettings.cs
@@ -40,15 +40,15 @@ public interface IStorageSettings
     IReadOnlyCollection<StorageProviderDefinition> GetStorageProviderDefinitions ();
 
     /// <summary>
-    /// Gets the <see cref="StorageProviderDefinition"/> for the given <paramref name="classDefinition"/>.
+    /// Gets the <see cref="StorageProviderDefinition"/> for the given <paramref name="typeDefinition"/>.
     /// </summary>
-    /// <param name="classDefinition">A <see cref="ClassDefinition"/>. Must not be <see langword="null"/>.</param>
+    /// <param name="typeDefinition">A <see cref="TypeDefinition"/>. Must not be <see langword="null"/>.</param>
     /// <returns>
-    /// The <see cref="StorageProviderDefinition"/> associated via the <paramref name="classDefinition"/>'s storage group
-    /// or the default <see cref="StorageProviderDefinition"/> if the <see cref="ClassDefinition"/> is not assigned to a storage group.
+    /// The <see cref="StorageProviderDefinition"/> associated via the <paramref name="typeDefinition"/>'s storage group
+    /// or the default <see cref="StorageProviderDefinition"/> if the <see cref="TypeDefinition"/> is not assigned to a storage group.
     /// </returns>
-    /// <exception cref="ConfigurationException">Thrown if no <see cref="StorageProviderDefinition"/> could be resolved for the <paramref name="classDefinition"/>.</exception>
-    StorageProviderDefinition GetStorageProviderDefinition (ClassDefinition classDefinition);
+    /// <exception cref="ConfigurationException">Thrown if no <see cref="StorageProviderDefinition"/> could be resolved for the <paramref name="typeDefinition"/>.</exception>
+    StorageProviderDefinition GetStorageProviderDefinition (TypeDefinition typeDefinition);
 
     /// <summary>
     /// Gets the <see cref="StorageProviderDefinition"/> for the given <paramref name="storageGroupTypeOrNull"/>.
diff --git a/Remotion/Data/DomainObjects/Persistence/Configuration/StorageSettings.cs b/Remotion/Data/DomainObjects/Persistence/Configuration/StorageSettings.cs
index 962fb2a677..97f82a37d5 100644
--- a/Remotion/Data/DomainObjects/Persistence/Configuration/StorageSettings.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Configuration/StorageSettings.cs
@@ -59,11 +59,11 @@ public StorageSettings (
     public IReadOnlyCollection<StorageProviderDefinition> GetStorageProviderDefinitions () => _storageProviderDefinitions;
 
     /// <inheritdoc />
-    public StorageProviderDefinition GetStorageProviderDefinition (ClassDefinition classDefinition)
+    public StorageProviderDefinition GetStorageProviderDefinition (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      var storageGroupTypeOrNull = classDefinition.StorageGroupType;
+      var storageGroupTypeOrNull = typeDefinition.StorageGroupType;
 
       return GetStorageProviderDefinition(storageGroupTypeOrNull);
     }
diff --git a/Remotion/Data/DomainObjects/Persistence/IStorageProviderDefinitionFinder.cs b/Remotion/Data/DomainObjects/Persistence/IStorageProviderDefinitionFinder.cs
index a54d7302c9..2542c33c5f 100644
--- a/Remotion/Data/DomainObjects/Persistence/IStorageProviderDefinitionFinder.cs
+++ b/Remotion/Data/DomainObjects/Persistence/IStorageProviderDefinitionFinder.cs
@@ -25,6 +25,6 @@ namespace Remotion.Data.DomainObjects.Persistence
   /// </summary>
   public interface IStorageProviderDefinitionFinder
   {
-    StorageProviderDefinition GetStorageProviderDefinition (ClassDefinition classDefinition, string? errorMessageContext);
+    StorageProviderDefinition GetStorageProviderDefinition (TypeDefinition typeDefinition, string? errorMessageContext);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Persistence/Model/IPersistenceModelLoader.cs b/Remotion/Data/DomainObjects/Persistence/Model/IPersistenceModelLoader.cs
index 525df6040b..ae70a82c17 100644
--- a/Remotion/Data/DomainObjects/Persistence/Model/IPersistenceModelLoader.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Model/IPersistenceModelLoader.cs
@@ -25,6 +25,6 @@ namespace Remotion.Data.DomainObjects.Persistence.Model
   /// <threadsafety static="true" instance="true"/>
   public interface IPersistenceModelLoader : IPersistenceModelValidatorFactory
   {
-    void ApplyPersistenceModelToHierarchy (ClassDefinition classDefinition);
+    void ApplyPersistenceModelToHierarchy (TypeDefinition typeDefinition);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Persistence/Model/IPersistenceModelValidatorFactory.cs b/Remotion/Data/DomainObjects/Persistence/Model/IPersistenceModelValidatorFactory.cs
index 7e7f7e22c2..20cdb92cc5 100644
--- a/Remotion/Data/DomainObjects/Persistence/Model/IPersistenceModelValidatorFactory.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Model/IPersistenceModelValidatorFactory.cs
@@ -25,6 +25,6 @@ namespace Remotion.Data.DomainObjects.Persistence.Model
   /// </summary>
   public interface IPersistenceModelValidatorFactory
   {
-    IPersistenceMappingValidator CreatePersistenceMappingValidator (ClassDefinition classDefinition);
+    IPersistenceMappingValidator CreatePersistenceMappingValidator (TypeDefinition typeDefinition);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Persistence/NonPersistent/NonPersistentPersistenceModelLoader.cs b/Remotion/Data/DomainObjects/Persistence/NonPersistent/NonPersistentPersistenceModelLoader.cs
index c4053043d4..a42c3a1805 100644
--- a/Remotion/Data/DomainObjects/Persistence/NonPersistent/NonPersistentPersistenceModelLoader.cs
+++ b/Remotion/Data/DomainObjects/Persistence/NonPersistent/NonPersistentPersistenceModelLoader.cs
@@ -23,6 +23,7 @@
 using Remotion.Data.DomainObjects.Persistence.Model;
 using Remotion.Data.DomainObjects.Persistence.NonPersistent.Model;
 using Remotion.Data.DomainObjects.Persistence.NonPersistent.Validation;
+using Remotion.Reflection;
 using Remotion.Utilities;
 
 namespace Remotion.Data.DomainObjects.Persistence.NonPersistent
@@ -41,64 +42,53 @@ public NonPersistentPersistenceModelLoader (StorageProviderDefinition storagePro
       StorageProviderDefinition = storageProviderDefinition;
     }
 
-    public IPersistenceMappingValidator CreatePersistenceMappingValidator (ClassDefinition classDefinition)
+    public IPersistenceMappingValidator CreatePersistenceMappingValidator (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
       return new PersistenceMappingValidator(
           new PropertyStorageClassIsSupportedByStorageProviderValidationRule(),
-          new RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRule());
+          new RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRule());
     }
 
-    public void ApplyPersistenceModelToHierarchy (ClassDefinition classDefinition)
+    public void ApplyPersistenceModelToHierarchy (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
+      InlineTypeDefinitionWalker.WalkDescendants(
+          typeDefinition,
+          EnsureStoragePropertiesCreated,
+          interfaceDefinition => throw new NotImplementedException("Interfaces are not supported.")); // TODO R2I Linq: Add support for interfaces
 
-      ClassDefinition[] derivedClasses = classDefinition.GetAllDerivedClasses();
-      var allClassDefinitions = new[] { classDefinition }.Concat(derivedClasses);
-
-      // ReSharper disable PossibleMultipleEnumeration - multiple enumeration is okay here.
-      EnsureAllStoragePropertiesCreated(allClassDefinitions);
-      EnsureAllStorageEntitiesCreated(allClassDefinitions);
-      // ReSharper restore PossibleMultipleEnumeration
-    }
-
-    private void EnsureAllStorageEntitiesCreated (IEnumerable<ClassDefinition> classDefinitions)
-    {
-      foreach (var classDefinition in classDefinitions)
-        EnsureStorageEntitiesCreated(classDefinition);
+      InlineTypeDefinitionWalker.WalkDescendants(
+          typeDefinition,
+          EnsureStorageEntitiesCreated,
+          interfaceDefinition => throw new NotImplementedException("Interfaces are not supported.")); // TODO R2I Linq: Add support for interfaces
     }
 
-    private void EnsureStorageEntitiesCreated (ClassDefinition classDefinition)
+    private void EnsureStorageEntitiesCreated (TypeDefinition typeDefinition)
     {
-      if (!classDefinition.HasStorageEntityDefinitionBeenSet)
+      if (!typeDefinition.HasStorageEntityDefinitionBeenSet)
       {
-        var storageEntity = CreateEntityDefinition(classDefinition);
-        classDefinition.SetStorageEntity(storageEntity);
+        var storageEntity = CreateEntityDefinition(typeDefinition);
+        typeDefinition.SetStorageEntity(storageEntity);
       }
-      else if (!classDefinition.IsNonPersistent())
+      else if (!typeDefinition.IsNonPersistent())
       {
         throw new InvalidOperationException(
             string.Format(
-                "The storage entity definition of class '{0}' is not of type '{1}'.",
-                classDefinition.ID,
+                "The storage entity definition of type '{0}' is not of type '{1}'.",
+                typeDefinition.Type.GetFullNameSafe(),
                 typeof(NonPersistentStorageEntity).Name));
       }
 
-      Assertion.DebugIsNotNull(classDefinition.StorageEntityDefinition, "classDefinition.StorageEntityDefinition != null");
-      Assertion.DebugAssert(classDefinition.StorageEntityDefinition is NonPersistentStorageEntity, "classDefinition.StorageEntityDefinition is NonPersistentStorageEntity");
-    }
-
-    private void EnsureAllStoragePropertiesCreated (IEnumerable<ClassDefinition> classDefinitions)
-    {
-      foreach (var classDefinition in classDefinitions)
-        EnsureStoragePropertiesCreated(classDefinition);
+      Assertion.DebugIsNotNull(typeDefinition.StorageEntityDefinition, "typeDefinition.StorageEntityDefinition != null");
+      Assertion.DebugAssert(typeDefinition.StorageEntityDefinition is NonPersistentStorageEntity, "classDefinition.StorageEntityDefinition is NonPersistentStorageEntity");
     }
 
-    private void EnsureStoragePropertiesCreated (ClassDefinition classDefinition)
+    private void EnsureStoragePropertiesCreated (TypeDefinition typeDefinition)
     {
-      foreach (var propertyDefinition in classDefinition.MyPropertyDefinitions.Where(pd => pd.StorageClass == StorageClass.Persistent))
+      foreach (var propertyDefinition in typeDefinition.MyPropertyDefinitions.Where(pd => pd.StorageClass == StorageClass.Persistent))
       {
         if (!propertyDefinition.HasStoragePropertyDefinitionBeenSet)
         {
@@ -108,9 +98,9 @@ private void EnsureStoragePropertiesCreated (ClassDefinition classDefinition)
         {
           throw new InvalidOperationException(
               string.Format(
-                  "The property definition '{0}' of class '{1}' has a storage property type of '{2}' when only '{3}' is supported.",
+                  "The property definition '{0}' of type '{1}' has a storage property type of '{2}' when only '{3}' is supported.",
                   propertyDefinition.PropertyName,
-                  classDefinition.ID,
+                  typeDefinition.Type.GetFullNameSafe(),
                   propertyDefinition.StoragePropertyDefinition.GetType(),
                   typeof(NonPersistentStorageProperty).Name));
         }
@@ -119,7 +109,7 @@ private void EnsureStoragePropertiesCreated (ClassDefinition classDefinition)
       }
     }
 
-    private IStorageEntityDefinition CreateEntityDefinition (ClassDefinition classDefinition)
+    private IStorageEntityDefinition CreateEntityDefinition (TypeDefinition typeDefinition)
     {
       return new NonPersistentStorageEntity(StorageProviderDefinition);
     }
diff --git a/Remotion/Data/DomainObjects/Persistence/NonPersistent/NonPersistentProvider.cs b/Remotion/Data/DomainObjects/Persistence/NonPersistent/NonPersistentProvider.cs
index 1001fdd79d..3855bbd2c2 100644
--- a/Remotion/Data/DomainObjects/Persistence/NonPersistent/NonPersistentProvider.cs
+++ b/Remotion/Data/DomainObjects/Persistence/NonPersistent/NonPersistentProvider.cs
@@ -44,7 +44,7 @@ public override IEnumerable<DataContainer> LoadDataContainersByRelatedID (
       CheckDisposed();
       ArgumentUtility.CheckNotNull("relationEndPointDefinition", relationEndPointDefinition);
       ArgumentUtility.CheckNotNull("relatedID", relatedID);
-      CheckClassDefinition(relationEndPointDefinition.ClassDefinition, "classDefinition");
+      CheckTypeDefinition(relationEndPointDefinition.TypeDefinition, "typeDefinition");
 
       return new DataContainerCollection();
     }
@@ -85,7 +85,7 @@ public override ObjectID CreateNewObjectID (ClassDefinition classDefinition)
     {
       CheckDisposed();
       ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
-      CheckClassDefinition(classDefinition, "classDefinition");
+      CheckTypeDefinition(classDefinition, "classDefinition");
 
       return new ObjectID(classDefinition, Guid.NewGuid());
     }
@@ -128,14 +128,14 @@ private ObjectID CheckStorageProvider (ObjectID id, string argumentName)
       return id;
     }
 
-    private void CheckClassDefinition (ClassDefinition classDefinition, string argumentName)
+    private void CheckTypeDefinition (TypeDefinition typeDefinition, string argumentName)
     {
-      if (classDefinition.StorageEntityDefinition.StorageProviderDefinition != StorageProviderDefinition)
+      if (typeDefinition.StorageEntityDefinition.StorageProviderDefinition != StorageProviderDefinition)
       {
         throw CreateArgumentException(
             argumentName,
-            "The StorageProviderID '{0}' of the provided ClassDefinition does not match with this StorageProvider's ID '{1}'.",
-            classDefinition.StorageEntityDefinition.StorageProviderDefinition.Name,
+            "The StorageProviderID '{0}' of the provided TypeDefinition does not match with this StorageProvider's ID '{1}'.",
+            typeDefinition.StorageEntityDefinition.StorageProviderDefinition.Name,
             StorageProviderDefinition.Name);
       }
     }
diff --git a/Remotion/Data/DomainObjects/Persistence/NonPersistent/Validation/PropertyStorageClassIsSupportedByStorageProviderValidationRule.cs b/Remotion/Data/DomainObjects/Persistence/NonPersistent/Validation/PropertyStorageClassIsSupportedByStorageProviderValidationRule.cs
index 1a5c5237b2..13771a4a2d 100644
--- a/Remotion/Data/DomainObjects/Persistence/NonPersistent/Validation/PropertyStorageClassIsSupportedByStorageProviderValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Persistence/NonPersistent/Validation/PropertyStorageClassIsSupportedByStorageProviderValidationRule.cs
@@ -27,11 +27,11 @@ namespace Remotion.Data.DomainObjects.Persistence.NonPersistent.Validation
   /// </summary>
   public class PropertyStorageClassIsSupportedByStorageProviderValidationRule : IPersistenceMappingValidationRule
   {
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return from PropertyDefinition propertyDefinition in classDefinition.MyPropertyDefinitions
+      return from PropertyDefinition propertyDefinition in typeDefinition.MyPropertyDefinitions
           select Validate(propertyDefinition);
     }
 
@@ -39,9 +39,9 @@ private MappingValidationResult Validate (PropertyDefinition propertyDefinition)
     {
       ArgumentUtility.CheckNotNull("propertyDefinition", propertyDefinition);
 
-      if (propertyDefinition.StorageClass == StorageClass.Persistent && propertyDefinition.ClassDefinition.HasStorageEntityDefinitionBeenSet)
+      if (propertyDefinition.StorageClass == StorageClass.Persistent && propertyDefinition.TypeDefinition.HasStorageEntityDefinitionBeenSet)
       {
-        if (propertyDefinition.ClassDefinition.IsNonPersistent())
+        if (propertyDefinition.TypeDefinition.IsNonPersistent())
         {
           return MappingValidationResult.CreateInvalidResultForProperty(
               propertyDefinition.PropertyInfo,
diff --git a/Remotion/Data/DomainObjects/Persistence/NonPersistent/Validation/RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRule.cs b/Remotion/Data/DomainObjects/Persistence/NonPersistent/Validation/RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRule.cs
similarity index 76%
rename from Remotion/Data/DomainObjects/Persistence/NonPersistent/Validation/RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRule.cs
rename to Remotion/Data/DomainObjects/Persistence/NonPersistent/Validation/RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRule.cs
index 10d90b9718..45cea9efb6 100644
--- a/Remotion/Data/DomainObjects/Persistence/NonPersistent/Validation/RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Persistence/NonPersistent/Validation/RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRule.cs
@@ -27,17 +27,17 @@ namespace Remotion.Data.DomainObjects.Persistence.NonPersistent.Validation
   /// <summary>
   /// Validates that a persistent relation property does not reference non-persistent classes.
   /// </summary>
-  public class RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRule : IPersistenceMappingValidationRule
+  public class RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRule : IPersistenceMappingValidationRule
   {
-    public RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRule ()
+    public RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRule ()
     {
     }
 
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return from IRelationEndPointDefinition endPointDefinition in classDefinition.MyRelationEndPointDefinitions
+      return from IRelationEndPointDefinition endPointDefinition in typeDefinition.MyRelationEndPointDefinitions
           select Validate(endPointDefinition);
     }
 
@@ -48,14 +48,14 @@ private MappingValidationResult Validate (IRelationEndPointDefinition endPointDe
         var oppositeEndPointDefinition = endPointDefinition.GetOppositeEndPointDefinition();
 
         if (relationEndPointDefinition.PropertyDefinition.StorageClass == StorageClass.Persistent
-            && oppositeEndPointDefinition.ClassDefinition.HasStorageEntityDefinitionBeenSet
-            && oppositeEndPointDefinition.ClassDefinition.IsNonPersistent())
+            && oppositeEndPointDefinition.TypeDefinition.HasStorageEntityDefinitionBeenSet
+            && oppositeEndPointDefinition.TypeDefinition.IsNonPersistent())
         {
           return MappingValidationResult.CreateInvalidResultForProperty(
               relationEndPointDefinition.PropertyInfo,
               "The relation property is defined as persistent but the referenced type '{0}' is non-persistent. "
               + "Persistent relation properties may only reference persistent types.",
-              oppositeEndPointDefinition.ClassDefinition.ClassType.GetFullNameSafe());
+              oppositeEndPointDefinition.TypeDefinition.Type.GetFullNameSafe());
         }
       }
 
diff --git a/Remotion/Data/DomainObjects/Persistence/PersistenceManager.cs b/Remotion/Data/DomainObjects/Persistence/PersistenceManager.cs
index c207ffe321..d2876967c2 100644
--- a/Remotion/Data/DomainObjects/Persistence/PersistenceManager.cs
+++ b/Remotion/Data/DomainObjects/Persistence/PersistenceManager.cs
@@ -322,7 +322,7 @@ private DataContainerCollection LoadOppositeDataContainers (RelationEndPointID r
 
       var oppositeEndPointDefinition = relationEndPointDefinition.GetOppositeEndPointDefinition();
       var oppositeProvider =
-          _storageProviderManager.GetMandatory(oppositeEndPointDefinition.ClassDefinition.StorageEntityDefinition.StorageProviderDefinition.Name);
+          _storageProviderManager.GetMandatory(oppositeEndPointDefinition.TypeDefinition.StorageEntityDefinition.StorageProviderDefinition.Name);
 
       SortExpressionDefinition? sortExpression;
       if (relationEndPointDefinition is DomainObjectCollectionRelationEndPointDefinition domainObjectCollectionRelationEndPointDefinition)
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/IRdbmsPersistenceModelProvider.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/IRdbmsPersistenceModelProvider.cs
index 87c4bfd6b0..76e6bc05b2 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/IRdbmsPersistenceModelProvider.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/IRdbmsPersistenceModelProvider.cs
@@ -26,7 +26,7 @@ namespace Remotion.Data.DomainObjects.Persistence.Rdbms
   /// </summary>
   public interface IRdbmsPersistenceModelProvider
   {
-    IRdbmsStorageEntityDefinition GetEntityDefinition (ClassDefinition classDefinition);
+    IRdbmsStorageEntityDefinition GetEntityDefinition (TypeDefinition typeDefinition);
     IRdbmsStoragePropertyDefinition GetStoragePropertyDefinition (PropertyDefinition propertyDefinition);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/IStorageProviderSerializer.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/IStorageProviderSerializer.cs
index 7268c804bf..e9a5a9bb9a 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/IStorageProviderSerializer.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/IStorageProviderSerializer.cs
@@ -26,6 +26,6 @@ namespace Remotion.Data.DomainObjects.Persistence.Rdbms.MappingExport
   /// </summary>
   public interface IStorageProviderSerializer
   {
-    XElement Serialize (IEnumerable<ClassDefinition> classDefinitions, RdbmsProviderDefinition providerDefinition);
+    XElement Serialize (IEnumerable<TypeDefinition> typeDefinitions, RdbmsProviderDefinition providerDefinition);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/ITableSerializer.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/ITableSerializer.cs
index 9418ac4f9b..38faa385d7 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/ITableSerializer.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/ITableSerializer.cs
@@ -22,10 +22,10 @@
 namespace Remotion.Data.DomainObjects.Persistence.Rdbms.MappingExport
 {
   /// <summary>
-  /// Defines an API for creating an xml fragment which describes how the <see cref="ClassDefinition"/> maps to database tables.
+  /// Defines an API for creating an xml fragment which describes how the <see cref="TypeDefinition"/> maps to database tables.
   /// </summary>
   public interface ITableSerializer
   {
-    IEnumerable<XElement> Serialize (ClassDefinition classDefinition);
+    IEnumerable<XElement> Serialize (TypeDefinition typeDefinition);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/IClassSerializer.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/ITypeSerializer.cs
similarity index 88%
rename from Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/IClassSerializer.cs
rename to Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/ITypeSerializer.cs
index 3961f8c7c6..d730c0b7be 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/IClassSerializer.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/ITypeSerializer.cs
@@ -21,10 +21,10 @@
 namespace Remotion.Data.DomainObjects.Persistence.Rdbms.MappingExport
 {
   /// <summary>
-  /// Defines an API for creating an xml fragment which contains the <see cref="ClassDefinition"/> metadata.
+  /// Defines an API for creating an xml fragment which contains the <see cref="TypeDefinition"/> metadata.
   /// </summary>
-  public interface IClassSerializer
+  public interface ITypeSerializer
   {
-    XElement Serialize (ClassDefinition classDefinition);
+    XElement Serialize (TypeDefinition typeDefinition);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/MappingSerializer.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/MappingSerializer.cs
index 400b3695d4..6ffc91e79e 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/MappingSerializer.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/MappingSerializer.cs
@@ -42,13 +42,13 @@ public MappingSerializer (
       _storageProviderSerializerFactory = storageProviderSerializerFactory;
     }
 
-    public XDocument Serialize (IEnumerable<ClassDefinition> classDefinitions)
+    public XDocument Serialize (IEnumerable<TypeDefinition> typeDefinitions)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
-      var classDefinitionsByStorageProvider = classDefinitions
-          .Where(cd => cd.StorageEntityDefinition.StorageProviderDefinition is RdbmsProviderDefinition)
-          .GroupBy(cd => (RdbmsProviderDefinition)cd.StorageEntityDefinition.StorageProviderDefinition);
+      var classDefinitionsByStorageProvider = typeDefinitions
+          .Where(td => td.StorageEntityDefinition.StorageProviderDefinition is RdbmsProviderDefinition)
+          .GroupBy(td => (RdbmsProviderDefinition)td.StorageEntityDefinition.StorageProviderDefinition);
 
       var mappingElement = new XElement(Constants.Namespace + "mapping");
       var enumElements = new List<XElement>();
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/StorageProviderSerializer.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/StorageProviderSerializer.cs
index 29098a1405..66a47d04ec 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/StorageProviderSerializer.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/StorageProviderSerializer.cs
@@ -28,28 +28,28 @@ namespace Remotion.Data.DomainObjects.Persistence.Rdbms.MappingExport
   /// </summary>
   public class StorageProviderSerializer : IStorageProviderSerializer
   {
-    private readonly IClassSerializer _classSerializer;
+    private readonly ITypeSerializer _typeSerializer;
 
-    public StorageProviderSerializer (IClassSerializer classSerializer)
+    public StorageProviderSerializer (ITypeSerializer typeSerializer)
     {
-      ArgumentUtility.CheckNotNull("classSerializer", classSerializer);
+      ArgumentUtility.CheckNotNull("typeSerializer", typeSerializer);
 
-      _classSerializer = classSerializer;
+      _typeSerializer = typeSerializer;
     }
 
-    public IClassSerializer ClassSerializer
+    public ITypeSerializer TypeSerializer
     {
-      get { return _classSerializer; }
+      get { return _typeSerializer; }
     }
 
-    public XElement Serialize (IEnumerable<ClassDefinition> classDefinitions, RdbmsProviderDefinition providerDefinition)
+    public XElement Serialize (IEnumerable<TypeDefinition> typeDefinitions, RdbmsProviderDefinition providerDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
       ArgumentUtility.CheckNotNull("providerDefinition", providerDefinition);
 
       return new XElement(Constants.Namespace + "storageProvider",
               new XAttribute("name", providerDefinition.Name),
-              classDefinitions.Select(c => _classSerializer.Serialize(c)));
+              typeDefinitions.Select(td => _typeSerializer.Serialize(td)));
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/TableSerializer.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/TableSerializer.cs
index 035595972a..9358aa36ec 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/TableSerializer.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/TableSerializer.cs
@@ -38,37 +38,37 @@ public TableSerializer (IPropertySerializer propertySerializer)
       _propertySerializer = propertySerializer;
     }
 
-    public IEnumerable<XElement> Serialize (ClassDefinition classDefinition)
+    public IEnumerable<XElement> Serialize (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      var tableDefinition = GetTableDefinition(classDefinition);
+      var tableDefinition = GetTableDefinition(typeDefinition);
       if (tableDefinition == null)
         yield break;
 
-      var storageProviderDefinition = (RdbmsProviderDefinition)classDefinition.StorageEntityDefinition.StorageProviderDefinition;
+      var storageProviderDefinition = (RdbmsProviderDefinition)typeDefinition.StorageEntityDefinition.StorageProviderDefinition;
       var persistenceModelProvider = storageProviderDefinition.Factory.CreateRdbmsPersistenceModelProvider(storageProviderDefinition);
 
       yield return new XElement(
           Constants.Namespace + "table",
           new XAttribute("name", tableDefinition.TableName.EntityName),
-          GetPersistentPropertyDefinitions(classDefinition)
+          GetPersistentPropertyDefinitions(typeDefinition)
               .Select(p => _propertySerializer.Serialize(p, persistenceModelProvider))
           );
     }
 
-    private TableDefinition? GetTableDefinition (ClassDefinition classDefinition)
+    private TableDefinition? GetTableDefinition (TypeDefinition typeDefinition)
     {
-      if (classDefinition.StorageEntityDefinition is FilterViewDefinition)
-        return ((FilterViewDefinition)classDefinition.StorageEntityDefinition).GetBaseTable();
+      if (typeDefinition.StorageEntityDefinition is FilterViewDefinition)
+        return ((FilterViewDefinition)typeDefinition.StorageEntityDefinition).GetBaseTable();
 
-      if (classDefinition.StorageEntityDefinition is TableDefinition)
-        return (TableDefinition)classDefinition.StorageEntityDefinition;
+      if (typeDefinition.StorageEntityDefinition is TableDefinition)
+        return (TableDefinition)typeDefinition.StorageEntityDefinition;
 
       return null;
     }
 
-    private IEnumerable<PropertyDefinition> GetPersistentPropertyDefinitions (ClassDefinition classDefinition)
+    private IEnumerable<PropertyDefinition> GetPersistentPropertyDefinitions (TypeDefinition classDefinition)
     {
       return classDefinition.GetPropertyDefinitions().Where(p => p.StorageClass == StorageClass.Persistent);
     }
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/ClassSerializer.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/TypeSerializer.cs
similarity index 82%
rename from Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/ClassSerializer.cs
rename to Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/TypeSerializer.cs
index fca2ba805c..f09f94e0bb 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/ClassSerializer.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/MappingExport/TypeSerializer.cs
@@ -23,22 +23,25 @@
 namespace Remotion.Data.DomainObjects.Persistence.Rdbms.MappingExport
 {
   /// <summary>
-  /// Default implementation for <see cref="IClassSerializer"/>
+  /// Default implementation for <see cref="ITypeSerializer"/>
   /// </summary>
-  public class ClassSerializer : IClassSerializer
+  public class TypeSerializer : ITypeSerializer
   {
     private readonly ITableSerializer _tableSerializer;
 
-    public ClassSerializer (ITableSerializer tableSerializer)
+    public TypeSerializer (ITableSerializer tableSerializer)
     {
       ArgumentUtility.CheckNotNull("tableSerializer", tableSerializer);
 
       _tableSerializer = tableSerializer;
     }
 
-    public XElement Serialize (ClassDefinition classDefinition)
+    public XElement Serialize (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
+
+      if (typeDefinition is not ClassDefinition classDefinition)
+        throw new NotSupportedException("Only class definitions are supported"); // TODO R2I Mapping: Add support for interfaces
 
       return new XElement(
           Constants.Namespace + "class",
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/DataStoragePropertyDefinitionFactory.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/DataStoragePropertyDefinitionFactory.cs
index cb73fae6f6..7fe4f370ab 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/DataStoragePropertyDefinitionFactory.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/DataStoragePropertyDefinitionFactory.cs
@@ -56,7 +56,7 @@ public virtual IRdbmsStoragePropertyDefinition CreateStoragePropertyDefinition (
       ArgumentUtility.CheckNotNull("propertyDefinition", propertyDefinition);
 
       var relationEndPointDefinition =
-          (RelationEndPointDefinition?)propertyDefinition.ClassDefinition.GetRelationEndPointDefinition(propertyDefinition.PropertyName);
+          (RelationEndPointDefinition?)propertyDefinition.TypeDefinition.GetRelationEndPointDefinition(propertyDefinition.PropertyName);
       if (relationEndPointDefinition != null)
       {
         Assertion.IsTrue(propertyDefinition.PropertyType == typeof(ObjectID));
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ForeignKeyConstraintDefinitionFactory.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ForeignKeyConstraintDefinitionFactory.cs
index d9bb940594..d999599bf1 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ForeignKeyConstraintDefinitionFactory.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ForeignKeyConstraintDefinitionFactory.cs
@@ -69,29 +69,32 @@ public IEnumerable<ForeignKeyConstraintDefinition> CreateForeignKeyConstraints (
           .Concat(classDefinition.GetAllDerivedClasses());
 
       return (from classDefinitionInHierarchy in allClassDefinitionsInHierarchy
-          from endPointDefinition in classDefinitionInHierarchy.MyRelationEndPointDefinitions
-          where !endPointDefinition.IsVirtual
-          let referencedClassDefinition = endPointDefinition.ClassDefinition
-              .GetMandatoryRelationEndPointDefinition(
-                  Assertion.IsNotNull(endPointDefinition.PropertyName, "endPointDefinition.PropertyName != null when endPointDefinition.IsVirtual == false"))
-              .GetOppositeClassDefinition()
-          let propertyDefinition = ((RelationEndPointDefinition)endPointDefinition).PropertyDefinition
-          where propertyDefinition.StorageClass == StorageClass.Persistent
-          let referencingStorageProperty =
-              (IObjectIDStoragePropertyDefinition)_persistenceModelProvider.GetStoragePropertyDefinition(propertyDefinition)
-          where referencingStorageProperty.CanCreateForeignKeyConstraint
-          let referencedTableName = FindTableName(referencedClassDefinition)
-          where referencedTableName != null
-          let referencedStoragePropertyDefinition = _infrastructureStoragePropertyDefinitionProvider.GetObjectIDStoragePropertyDefinition()
-          select referencingStorageProperty.CreateForeignKeyConstraint(
-              referencingColumns => _storageNameProvider.GetForeignKeyConstraintName(classDefinition, referencingColumns),
-              referencedTableName,
-              referencedStoragePropertyDefinition)
-          ).ToList();
+              from endPointDefinition in classDefinitionInHierarchy.MyRelationEndPointDefinitions
+              where !endPointDefinition.IsVirtual
+              let referencedClassDefinition = endPointDefinition.TypeDefinition
+                  .GetMandatoryRelationEndPointDefinition(
+                      Assertion.IsNotNull(endPointDefinition.PropertyName, "endPointDefinition.PropertyName != null when endPointDefinition.IsVirtual == false"))
+                  .GetOppositeTypeDefinition()
+              let propertyDefinition = ((RelationEndPointDefinition)endPointDefinition).PropertyDefinition
+              where propertyDefinition.StorageClass == StorageClass.Persistent
+              let referencingStorageProperty =
+                  (IObjectIDStoragePropertyDefinition)_persistenceModelProvider.GetStoragePropertyDefinition(propertyDefinition)
+              where referencingStorageProperty.CanCreateForeignKeyConstraint
+              let referencedTableName = FindTableName(referencedClassDefinition)
+              where referencedTableName != null
+              let referencedStoragePropertyDefinition = _infrastructureStoragePropertyDefinitionProvider.GetObjectIDStoragePropertyDefinition()
+              select referencingStorageProperty.CreateForeignKeyConstraint(
+                  referencingColumns => _storageNameProvider.GetForeignKeyConstraintName(classDefinition, referencingColumns),
+                  referencedTableName,
+                  referencedStoragePropertyDefinition)
+             ).ToList();
     }
 
-    private EntityNameDefinition? FindTableName (ClassDefinition classDefinition)
+    private EntityNameDefinition? FindTableName (TypeDefinition typeDefinition)
     {
+      if (typeDefinition is not ClassDefinition classDefinition) // TODO R2I Persistence: check if this makes sense after refactoring GetTableName
+        return null;
+
       var tableName = classDefinition
           .CreateSequence(cd => cd.BaseClass)
           .Select(cd => _storageNameProvider.GetTableName(cd))
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/IStorageNameProvider.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/IStorageNameProvider.cs
index df70442a69..95032bbf92 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/IStorageNameProvider.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/IStorageNameProvider.cs
@@ -32,7 +32,7 @@ public interface IStorageNameProvider
     string GetClassIDColumnName ();
     string GetTimestampColumnName ();
 
-    EntityNameDefinition? GetTableName (ClassDefinition classDefinition);
+    EntityNameDefinition? GetTableName (ClassDefinition classDefinition); // TODO R2I Persistence: check usages for required changes
     EntityNameDefinition GetViewName (ClassDefinition classDefinition);
     string GetColumnName (PropertyDefinition propertyDefinition);
     string GetRelationColumnName (RelationEndPointDefinition relationEndPointDefinition);
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/RdbmsPersistenceModelLoader.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/RdbmsPersistenceModelLoader.cs
index 17772d975a..fef9e2c74c 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/RdbmsPersistenceModelLoader.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/RdbmsPersistenceModelLoader.cs
@@ -23,6 +23,7 @@
 using Remotion.Data.DomainObjects.Persistence.NonPersistent.Validation;
 using Remotion.Data.DomainObjects.Persistence.Rdbms.Model.Validation;
 using Remotion.FunctionalProgramming;
+using Remotion.Reflection;
 using Remotion.Utilities;
 
 namespace Remotion.Data.DomainObjects.Persistence.Rdbms.Model.Building
@@ -74,7 +75,7 @@ public IRdbmsPersistenceModelProvider RdbmsPersistenceModelProvider
       get { return _rdbmsPersistenceModelProvider; }
     }
 
-    public IPersistenceMappingValidator CreatePersistenceMappingValidator (ClassDefinition classDefinition)
+    public IPersistenceMappingValidator CreatePersistenceMappingValidator (TypeDefinition typeDefinition)
     {
       return new PersistenceMappingValidator(
           new OnlyOneTablePerHierarchyValidationRule(),
@@ -82,56 +83,46 @@ public IPersistenceMappingValidator CreatePersistenceMappingValidator (ClassDefi
           new ClassAboveTableIsAbstractValidationRule(),
           new ColumnNamesAreUniqueWithinInheritanceTreeValidationRule(_rdbmsPersistenceModelProvider),
           new PropertyTypeIsSupportedByStorageProviderValidationRule(),
-          new RelationPropertyStorageClassMatchesReferencedClassDefinitionStorageClassValidationRule());
+          new RelationPropertyStorageClassMatchesReferencedTypeDefinitionStorageClassValidationRule());
     }
 
-    public void ApplyPersistenceModelToHierarchy (ClassDefinition classDefinition)
+    public void ApplyPersistenceModelToHierarchy (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      ClassDefinition[] derivedClasses = classDefinition.GetAllDerivedClasses();
-      var allClassDefinitions = new[] { classDefinition }.Concat(derivedClasses);
+      InlineTypeDefinitionWalker.WalkDescendants(
+          typeDefinition,
+          EnsureStoragePropertiesCreated,
+          interfaceDefinition => throw new NotImplementedException("Interfaces are not supported.")); // TODO R2I Linq: Add support for interfaces
 
-      // ReSharper disable PossibleMultipleEnumeration - multiple enumeration is okay here.
-      EnsureAllStoragePropertiesCreated(allClassDefinitions);
-      EnsureAllStorageEntitiesCreated(allClassDefinitions);
-      // ReSharper restore PossibleMultipleEnumeration
+      InlineTypeDefinitionWalker.WalkDescendants(
+          typeDefinition,
+          EnsureStorageEntitiesCreated,
+          interfaceDefinition => throw new NotImplementedException("Interfaces are not supported.")); // TODO R2I Linq: Add support for interfaces
     }
 
-    private void EnsureAllStorageEntitiesCreated (IEnumerable<ClassDefinition> classDefinitions)
+    private void EnsureStorageEntitiesCreated (TypeDefinition typeDefinition)
     {
-      foreach (var classDefinition in classDefinitions)
-        EnsureStorageEntitiesCreated(classDefinition);
-    }
-
-    private void EnsureStorageEntitiesCreated (ClassDefinition classDefinition)
-    {
-      if (!classDefinition.HasStorageEntityDefinitionBeenSet)
+      if (!typeDefinition.HasStorageEntityDefinitionBeenSet)
       {
-        var storageEntity = CreateEntityDefinition(classDefinition);
-        classDefinition.SetStorageEntity(storageEntity);
+        var storageEntity = CreateEntityDefinition(typeDefinition);
+        typeDefinition.SetStorageEntity(storageEntity);
       }
-      else if (!(classDefinition.StorageEntityDefinition is IRdbmsStorageEntityDefinition))
+      else if (!(typeDefinition.StorageEntityDefinition is IRdbmsStorageEntityDefinition))
       {
         throw new InvalidOperationException(
             string.Format(
-                "The storage entity definition of class '{0}' does not implement interface '{1}'.",
-                classDefinition.ID,
+                "The storage entity definition of type '{0}' does not implement interface '{1}'.",
+                typeDefinition.Type.GetFullNameSafe(),
                 typeof(IRdbmsStorageEntityDefinition).Name));
       }
 
-      Assertion.DebugIsNotNull(classDefinition.StorageEntityDefinition, "classDefinition.StorageEntityDefinition != null");
+      Assertion.DebugIsNotNull(typeDefinition.StorageEntityDefinition, "typeDefinition.StorageEntityDefinition != null");
     }
 
-    private void EnsureAllStoragePropertiesCreated (IEnumerable<ClassDefinition> classDefinitions)
+    private void EnsureStoragePropertiesCreated (TypeDefinition typeDefinition)
     {
-      foreach (var classDefinition in classDefinitions)
-        EnsureStoragePropertiesCreated(classDefinition);
-    }
-
-    private void EnsureStoragePropertiesCreated (ClassDefinition classDefinition)
-    {
-      foreach (var propertyDefinition in classDefinition.MyPropertyDefinitions.Where(pd => pd.StorageClass == StorageClass.Persistent))
+      foreach (var propertyDefinition in typeDefinition.MyPropertyDefinitions.Where(pd => pd.StorageClass == StorageClass.Persistent))
       {
         if (!propertyDefinition.HasStoragePropertyDefinitionBeenSet)
         {
@@ -142,9 +133,9 @@ private void EnsureStoragePropertiesCreated (ClassDefinition classDefinition)
         {
           throw new InvalidOperationException(
             string.Format(
-                "The property definition '{0}' of class '{1}' does not implement interface '{2}'.",
+                "The property definition '{0}' of type '{1}' does not implement interface '{2}'.",
                 propertyDefinition.PropertyName,
-                classDefinition.ID,
+                typeDefinition.Type.GetFullNameSafe(),
                 typeof(IRdbmsStoragePropertyDefinition).Name));
         }
 
@@ -152,8 +143,11 @@ private void EnsureStoragePropertiesCreated (ClassDefinition classDefinition)
       }
     }
 
-    private IStorageEntityDefinition CreateEntityDefinition (ClassDefinition classDefinition)
+    private IStorageEntityDefinition CreateEntityDefinition (TypeDefinition typeDefinition)
     {
+      if (typeDefinition is not ClassDefinition classDefinition)
+        throw new NotSupportedException("Only class definitions are supported."); // TODO R2I Mapping: property finder support for interfaces
+
       if (_storageNameProvider.GetTableName(classDefinition) != null)
         return _entityDefinitionFactory.CreateTableDefinition(classDefinition);
 
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ReflectionBasedStorageNameProvider.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ReflectionBasedStorageNameProvider.cs
index 278a9c6c3a..eb1b7f2c88 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ReflectionBasedStorageNameProvider.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ReflectionBasedStorageNameProvider.cs
@@ -49,7 +49,7 @@ public string GetTimestampColumnName ()
     {
       ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
 
-      var tableAttribute = AttributeUtility.GetCustomAttribute<DBTableAttribute>(classDefinition.ClassType, false);
+      var tableAttribute = AttributeUtility.GetCustomAttribute<DBTableAttribute>(classDefinition.Type, false);
       if (tableAttribute == null)
         return null;
 
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/RelationStoragePropertyDefinitionFactory.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/RelationStoragePropertyDefinitionFactory.cs
index ac39684036..5516ca9fa6 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/RelationStoragePropertyDefinitionFactory.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/RelationStoragePropertyDefinitionFactory.cs
@@ -83,7 +83,10 @@ public IRdbmsStoragePropertyDefinition CreateStoragePropertyDefinition (Relation
       var oppositeEndPointDefinition = relationEndPointDefinition.GetOppositeEndPointDefinition();
       var relationColumnName = _storageNameProvider.GetRelationColumnName(relationEndPointDefinition);
       var relationClassIDColumnName = _storageNameProvider.GetRelationClassIDColumnName(relationEndPointDefinition);
-      return CreateStoragePropertyDefinition(oppositeEndPointDefinition.ClassDefinition, relationColumnName, relationClassIDColumnName);
+      if (oppositeEndPointDefinition.TypeDefinition is not ClassDefinition oppositeEndPointClassDefinition)
+        throw new InvalidOperationException("Only class definitions are supported"); // TODO R2I Persistence: Support TypeDefinition
+
+      return CreateStoragePropertyDefinition(oppositeEndPointClassDefinition, relationColumnName, relationClassIDColumnName);
     }
 
     public virtual IRdbmsStoragePropertyDefinition CreateStoragePropertyDefinition (
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ValueStoragePropertyDefinitionFactory.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ValueStoragePropertyDefinitionFactory.cs
index db283d9aa9..a778b97ba9 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ValueStoragePropertyDefinitionFactory.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Building/ValueStoragePropertyDefinitionFactory.cs
@@ -18,6 +18,7 @@
 using System.Linq;
 using Remotion.Data.DomainObjects.Mapping;
 using Remotion.FunctionalProgramming;
+using Remotion.Reflection;
 using Remotion.Utilities;
 
 namespace Remotion.Data.DomainObjects.Persistence.Rdbms.Model.Building
@@ -62,9 +63,9 @@ public IRdbmsStoragePropertyDefinition CreateStoragePropertyDefinition (Property
       catch (NotSupportedException ex)
       {
         var message = string.Format(
-            "There was an error when retrieving storage type for property '{0}' (declaring class: '{1}'): {2}",
+            "There was an error when retrieving storage type for property '{0}' (declaring type: '{1}'): {2}",
             propertyDefinition.PropertyName,
-            propertyDefinition.ClassDefinition.ID,
+            propertyDefinition.TypeDefinition.Type.GetFullNameSafe(),
             ex.Message);
         return new UnsupportedStoragePropertyDefinition(propertyDefinition.PropertyType, message, ex);
       }
@@ -98,8 +99,11 @@ protected virtual bool MustBeNullable (PropertyDefinition propertyDefinition)
     {
       ArgumentUtility.CheckNotNull("propertyDefinition", propertyDefinition);
 
+      if (propertyDefinition.TypeDefinition is not ClassDefinition classDefinition) // TODO R2I Persistence: Support TypeDefinition
+        throw new NotSupportedException("Only class definitions are supported");
+
       // CreateSequence can deal with null source objects
-      var baseClasses = propertyDefinition.ClassDefinition.BaseClass.CreateSequence(cd => cd.BaseClass);
+      var baseClasses = classDefinition.BaseClass.CreateSequence(cd => cd.BaseClass);
       return baseClasses.Any(cd => _storageNameProvider.GetTableName(cd) != null);
     }
 
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/ClassAboveTableIsAbstractValidationRule.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/ClassAboveTableIsAbstractValidationRule.cs
index 20369237aa..59f58cb93a 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/ClassAboveTableIsAbstractValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/ClassAboveTableIsAbstractValidationRule.cs
@@ -32,11 +32,15 @@ public ClassAboveTableIsAbstractValidationRule ()
 
     }
 
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      if (!classDefinition.IsClassTypeResolved)
+      if (typeDefinition is not ClassDefinition classDefinition)
+      {
+        yield return MappingValidationResult.CreateValidResult();
+      }
+      else if (!classDefinition.IsTypeResolved)
       {
         yield return MappingValidationResult.CreateValidResult();
       }
@@ -55,10 +59,10 @@ public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefin
       else
       {
         yield return MappingValidationResult.CreateInvalidResultForType(
-            classDefinition.ClassType,
+            classDefinition.Type,
             "Neither class '{0}' nor its base classes are mapped to a table. "
             + "Make class '{0}' abstract or define a table for it or one of its base classes.",
-            classDefinition.ClassType.Name);
+            classDefinition.Type.Name);
       }
     }
 
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/ColumnNamesAreUniqueWithinInheritanceTreeValidationRule.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/ColumnNamesAreUniqueWithinInheritanceTreeValidationRule.cs
index 34a07da711..ca1c9997d5 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/ColumnNamesAreUniqueWithinInheritanceTreeValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/ColumnNamesAreUniqueWithinInheritanceTreeValidationRule.cs
@@ -38,11 +38,14 @@ public ColumnNamesAreUniqueWithinInheritanceTreeValidationRule (IRdbmsPersistenc
       _rdbmsPersistenceModelProvider = rdbmsPersistenceModelProvider;
     }
 
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
       var validationResults = new List<MappingValidationResult>();
+      if (typeDefinition is not ClassDefinition classDefinition) // TODO R2I Persistence: Support TypeDefinition
+        return validationResults;
+
       if (classDefinition.BaseClass == null) //if class definition is inheritance root class
       {
         var derivedPropertyDefinitions = classDefinition.GetAllDerivedClasses()
@@ -77,9 +80,9 @@ private IEnumerable<MappingValidationResult> ValidatePropertyGroup (string colum
                 "Property '{0}' of class '{1}' must not define storage specific name '{2}',"
                 + " because class '{3}' in same inheritance hierarchy already defines property '{4}' with the same storage specific name.",
                 differentProperty.PropertyInfo.Name,
-                differentProperty.ClassDefinition.ClassType.Name,
+                differentProperty.TypeDefinition.Type.Name,
                 columnName,
-                referenceProperty.ClassDefinition.ClassType.Name,
+                referenceProperty.TypeDefinition.Type.Name,
                 referenceProperty.PropertyInfo.Name);
           }
         }
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/OnlyOneTablePerHierarchyValidationRule.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/OnlyOneTablePerHierarchyValidationRule.cs
index 93df655d22..8cbbf1dd03 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/OnlyOneTablePerHierarchyValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/OnlyOneTablePerHierarchyValidationRule.cs
@@ -32,11 +32,15 @@ public OnlyOneTablePerHierarchyValidationRule ()
     {
     }
 
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      if (classDefinition.BaseClass != null && classDefinition.HasStorageEntityDefinitionBeenSet && classDefinition.StorageEntityDefinition is TableDefinition)
+      if (typeDefinition is not ClassDefinition classDefinition)
+      {
+        yield return MappingValidationResult.CreateValidResult();
+      }
+      else if (classDefinition.BaseClass != null && classDefinition.HasStorageEntityDefinitionBeenSet && classDefinition.StorageEntityDefinition is TableDefinition)
       {
         var baseClasses = classDefinition.BaseClass.CreateSequence(cd => cd.BaseClass);
         foreach (ClassDefinition baseClass in baseClasses)
@@ -45,10 +49,10 @@ public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefin
           if (baseClass.StorageEntityDefinition is TableDefinition)
           {
             yield return MappingValidationResult.CreateInvalidResultForType(
-                classDefinition.ClassType,
+                classDefinition.Type,
                 "Class '{0}' must not define a table when its base class '{1}' also defines one.",
-                classDefinition.ClassType.Name,
-                baseClass.ClassType.Name);
+                classDefinition.Type.Name,
+                baseClass.Type.Name);
           }
         }
       }
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/PropertyTypeIsSupportedByStorageProviderValidationRule.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/PropertyTypeIsSupportedByStorageProviderValidationRule.cs
index 41be36e7af..e21119e014 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/PropertyTypeIsSupportedByStorageProviderValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/PropertyTypeIsSupportedByStorageProviderValidationRule.cs
@@ -28,11 +28,11 @@ namespace Remotion.Data.DomainObjects.Persistence.Rdbms.Model.Validation
   /// </summary>
   public class PropertyTypeIsSupportedByStorageProviderValidationRule : IPersistenceMappingValidationRule
   {
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      return from PropertyDefinition propertyDefinition in classDefinition.MyPropertyDefinitions
+      return from PropertyDefinition propertyDefinition in typeDefinition.MyPropertyDefinitions
              select Validate(propertyDefinition);
     }
 
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/TableNamesAreDistinctWithinConcreteTableInheritanceHierarchyValidationRule.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/TableNamesAreDistinctWithinConcreteTableInheritanceHierarchyValidationRule.cs
index e75c1d2019..0b120e41be 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/TableNamesAreDistinctWithinConcreteTableInheritanceHierarchyValidationRule.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/Model/Validation/TableNamesAreDistinctWithinConcreteTableInheritanceHierarchyValidationRule.cs
@@ -33,9 +33,12 @@ public TableNamesAreDistinctWithinConcreteTableInheritanceHierarchyValidationRul
 
     }
 
-    public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefinition)
+    public IEnumerable<MappingValidationResult> Validate (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
+
+      if (typeDefinition is not ClassDefinition classDefinition)
+        yield break;
 
       if (classDefinition.BaseClass == null) //if class definition is inheritance root class
       {
@@ -45,10 +48,10 @@ public IEnumerable<MappingValidationResult> Validate (ClassDefinition classDefin
           if (allDistinctTableNames.Contains(tableName))
           {
             yield return MappingValidationResult.CreateInvalidResultForType(
-                classDefinition.ClassType,
+                classDefinition.Type,
                 "At least two classes in different inheritance branches derived from abstract class '{0}'"
                 + " specify the same entity name '{1}', which is not allowed.",
-                classDefinition.ClassType.Name,
+                classDefinition.Type.Name,
                 tableName);
           }
           else
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/RdbmsPersistenceModelProvider.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/RdbmsPersistenceModelProvider.cs
index 251d9e73d8..5567ea8b97 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/RdbmsPersistenceModelProvider.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/RdbmsPersistenceModelProvider.cs
@@ -17,6 +17,7 @@
 using System;
 using Remotion.Data.DomainObjects.Mapping;
 using Remotion.Data.DomainObjects.Persistence.Rdbms.Model;
+using Remotion.Reflection;
 using Remotion.Utilities;
 
 namespace Remotion.Data.DomainObjects.Persistence.Rdbms
@@ -26,30 +27,30 @@ namespace Remotion.Data.DomainObjects.Persistence.Rdbms
   /// </summary>
   public class RdbmsPersistenceModelProvider : IRdbmsPersistenceModelProvider
   {
-    public IRdbmsStorageEntityDefinition GetEntityDefinition (ClassDefinition classDefinition)
+    public IRdbmsStorageEntityDefinition GetEntityDefinition (TypeDefinition typeDefinition)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      if (!classDefinition.HasStorageEntityDefinitionBeenSet)
+      if (!typeDefinition.HasStorageEntityDefinitionBeenSet)
       {
         throw new RdbmsProviderException(
             string.Format(
-                "The Rdbms provider classes require a storage definition object of type '{0}' for class-definition '{1}', "
-                + "but that class has no storage definition object.",
+                "The Rdbms provider classes require a storage definition object of type '{0}' for type definition '{1}', "
+                + "but that type definition has no storage definition object.",
                 typeof(IRdbmsStorageEntityDefinition).Name,
-                classDefinition.ID));
+                typeDefinition.Type.GetFullNameSafe()));
       }
 
-      var storageEntityDefinitionAsIEntityDefinition = classDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition;
+      var storageEntityDefinitionAsIEntityDefinition = typeDefinition.StorageEntityDefinition as IRdbmsStorageEntityDefinition;
       if (storageEntityDefinitionAsIEntityDefinition == null)
       {
         throw new RdbmsProviderException(
             string.Format(
-                "The Rdbms provider classes require a storage definition object of type '{0}' for class-definition '{1}', "
-                + "but that class has a storage definition object of type '{2}'.",
+                "The Rdbms provider classes require a storage definition object of type '{0}' for type definition '{1}', "
+                + "but that type definition has a storage definition object of type '{2}'.",
                 typeof(IRdbmsStorageEntityDefinition).Name,
-                classDefinition.ID,
-                classDefinition.StorageEntityDefinition.GetType().Name));
+                typeDefinition.Type.GetFullNameSafe(),
+                typeDefinition.StorageEntityDefinition.GetType().Name));
       }
 
       return storageEntityDefinitionAsIEntityDefinition;
@@ -67,7 +68,7 @@ public IRdbmsStoragePropertyDefinition GetStoragePropertyDefinition (PropertyDef
                 + "but that property has no storage definition object.",
                 typeof(IRdbmsStoragePropertyDefinition).Name,
                 propertyDefinition.PropertyName,
-                propertyDefinition.ClassDefinition.ID));
+                propertyDefinition.TypeDefinition.Type.GetFullNameSafe()));
       }
 
       var storagePropertyDefinitionAsIColumnDefinition = propertyDefinition.StoragePropertyDefinition as IRdbmsStoragePropertyDefinition;
@@ -79,7 +80,7 @@ public IRdbmsStoragePropertyDefinition GetStoragePropertyDefinition (PropertyDef
                 + "but that property has a storage definition object of type '{3}'.",
                 typeof(IRdbmsStoragePropertyDefinition).Name,
                 propertyDefinition.PropertyName,
-                propertyDefinition.ClassDefinition.ID,
+                propertyDefinition.TypeDefinition.Type.GetFullNameSafe(),
                 propertyDefinition.StoragePropertyDefinition.GetType().Name));
       }
 
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/RdbmsProvider.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/RdbmsProvider.cs
index 2dcb2ac9cd..84334c7603 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/RdbmsProvider.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/RdbmsProvider.cs
@@ -275,7 +275,8 @@ public override IEnumerable<DataContainer> LoadDataContainersByRelatedID (
       CheckDisposed();
       ArgumentUtility.CheckNotNull("relationEndPointDefinition", relationEndPointDefinition);
       ArgumentUtility.CheckNotNull("relatedID", relatedID);
-      CheckClassDefinition(relationEndPointDefinition.ClassDefinition, "classDefinition");
+
+      CheckTypeDefinition(relationEndPointDefinition.TypeDefinition, "relationEndPointDefinition.TypeDefinition");
 
       Connect();
 
@@ -329,7 +330,7 @@ public override ObjectID CreateNewObjectID (ClassDefinition classDefinition)
     {
       CheckDisposed();
       ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
-      CheckClassDefinition(classDefinition, "classDefinition");
+      CheckTypeDefinition(classDefinition, "typeDefinition");
 
       return new ObjectID(classDefinition.ID, Guid.NewGuid());
     }
@@ -449,14 +450,14 @@ private ObjectID CheckStorageProvider (ObjectID id, string argumentName)
       return id;
     }
 
-    private void CheckClassDefinition (ClassDefinition classDefinition, string argumentName)
+    private void CheckTypeDefinition (TypeDefinition typeDefinition, string argumentName)
     {
-      if (classDefinition.StorageEntityDefinition.StorageProviderDefinition != StorageProviderDefinition)
+      if (typeDefinition.StorageEntityDefinition.StorageProviderDefinition != StorageProviderDefinition)
       {
         throw CreateArgumentException(
             argumentName,
-            "The StorageProvider '{0}' of the provided ClassDefinition does not match with this StorageProvider '{1}'.",
-            classDefinition.StorageEntityDefinition.StorageProviderDefinition.Name,
+            "The StorageProvider '{0}' of the provided TypeDefinition does not match with this StorageProvider '{1}'.",
+            typeDefinition.StorageEntityDefinition.StorageProviderDefinition.Name,
             StorageProviderDefinition.Name);
       }
     }
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/IRdbmsStorageEntityDefinitionProvider.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/IRdbmsStorageEntityDefinitionProvider.cs
index 0535a3bb7c..3494fc607b 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/IRdbmsStorageEntityDefinitionProvider.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/IRdbmsStorageEntityDefinitionProvider.cs
@@ -23,10 +23,10 @@ namespace Remotion.Data.DomainObjects.Persistence.Rdbms.SchemaGeneration
 {
   /// <summary>
   /// <see cref="IRdbmsStorageEntityDefinitionProvider"/> provides a strategy to get all <see cref="IRdbmsStorageEntityDefinition"/> objects for a collection of 
-  /// <see cref="ClassDefinition"/> instances. Reimplement this interface to influence which entities are processed by <see cref="ScriptGenerator"/>.
+  /// <see cref="TypeDefinition"/> instances. Reimplement this interface to influence which entities are processed by <see cref="ScriptGenerator"/>.
   /// </summary>
   public interface IRdbmsStorageEntityDefinitionProvider
   {
-    IEnumerable<IRdbmsStorageEntityDefinition> GetEntityDefinitions (IEnumerable<ClassDefinition> classDefinitions);
+    IEnumerable<IRdbmsStorageEntityDefinition> GetEntityDefinitions (IEnumerable<TypeDefinition> typeDefinitions);
   }
 }
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/RdbmsStorageEntityDefinitionProvider.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/RdbmsStorageEntityDefinitionProvider.cs
index df71f3309d..89236f21d7 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/RdbmsStorageEntityDefinitionProvider.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/RdbmsStorageEntityDefinitionProvider.cs
@@ -24,17 +24,17 @@
 namespace Remotion.Data.DomainObjects.Persistence.Rdbms.SchemaGeneration
 {
   /// <summary>
-  /// <see cref="RdbmsStorageEntityDefinitionProvider"/> returns a sequence of <see cref="IRdbmsStorageEntityDefinition"/> for the given <see cref="ClassDefinition"/> 
+  /// <see cref="RdbmsStorageEntityDefinitionProvider"/> returns a sequence of <see cref="IRdbmsStorageEntityDefinition"/> for the given <see cref="TypeDefinition"/> 
   /// instances.
   /// </summary>
   public class RdbmsStorageEntityDefinitionProvider : IRdbmsStorageEntityDefinitionProvider
   {
-    public IEnumerable<IRdbmsStorageEntityDefinition> GetEntityDefinitions (IEnumerable<ClassDefinition> classDefinitions)
+    public IEnumerable<IRdbmsStorageEntityDefinition> GetEntityDefinitions (IEnumerable<TypeDefinition> typeDefinitions)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
-      return classDefinitions
-          .Select(cd => cd.StorageEntityDefinition)
+      return typeDefinitions
+          .Select(td => td.StorageEntityDefinition)
           .OfType<IRdbmsStorageEntityDefinition>();
     }
   }
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/ScriptGenerator.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/ScriptGenerator.cs
index 05d4095cdc..9674106b4e 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/ScriptGenerator.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/SchemaGeneration/ScriptGenerator.cs
@@ -47,14 +47,14 @@ public ScriptGenerator (
       _scriptToStringConverter = scriptToStringConverter;
     }
 
-    public IEnumerable<Script> GetScripts (IEnumerable<ClassDefinition> classDefinitions)
+    public IEnumerable<Script> GetScripts (IEnumerable<TypeDefinition> typeDefinitions)
     {
-      ArgumentUtility.CheckNotNull("classDefinitions", classDefinitions);
+      ArgumentUtility.CheckNotNull("typeDefinitions", typeDefinitions);
 
       var classDefinitionsByStorageProvider =
-          from cd in classDefinitions
-          where cd.StorageEntityDefinition.StorageProviderDefinition is RdbmsProviderDefinition
-          group cd by cd.StorageEntityDefinition.StorageProviderDefinition
+          from td in typeDefinitions
+          where td.StorageEntityDefinition.StorageProviderDefinition is RdbmsProviderDefinition
+          group td by td.StorageEntityDefinition.StorageProviderDefinition
           into g
             select new { StorageProviderDefinition = (RdbmsProviderDefinition)g.Key, ClassDefinitions = g };
 
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/SqlServer/Sql2016/SqlStorageObjectFactory.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/SqlServer/Sql2016/SqlStorageObjectFactory.cs
index 5b1471f92e..1be66ef830 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/SqlServer/Sql2016/SqlStorageObjectFactory.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/SqlServer/Sql2016/SqlStorageObjectFactory.cs
@@ -307,13 +307,13 @@ public virtual IEnumSerializer CreateEnumSerializer ()
     public virtual IStorageProviderSerializer CreateStorageProviderSerializer (IEnumSerializer enumSerializer)
     {
       ArgumentUtility.CheckNotNull("enumSerializer", enumSerializer);
-      return new StorageProviderSerializer(CreateClassSerializer(enumSerializer));
+      return new StorageProviderSerializer(CreateTypeSerializer(enumSerializer));
     }
 
-    public virtual IClassSerializer CreateClassSerializer (IEnumSerializer enumSerializer)
+    public virtual ITypeSerializer CreateTypeSerializer (IEnumSerializer enumSerializer)
     {
       ArgumentUtility.CheckNotNull("enumSerializer", enumSerializer);
-      return new ClassSerializer(CreateTableSerializer(enumSerializer));
+      return new TypeSerializer(CreateTableSerializer(enumSerializer));
     }
 
     public virtual ITableSerializer CreateTableSerializer (IEnumSerializer enumSerializer)
diff --git a/Remotion/Data/DomainObjects/Persistence/Rdbms/StorageProviderCommands/Factories/RelationLookupCommandFactory.cs b/Remotion/Data/DomainObjects/Persistence/Rdbms/StorageProviderCommands/Factories/RelationLookupCommandFactory.cs
index 785dfdd159..561be651fe 100644
--- a/Remotion/Data/DomainObjects/Persistence/Rdbms/StorageProviderCommands/Factories/RelationLookupCommandFactory.cs
+++ b/Remotion/Data/DomainObjects/Persistence/Rdbms/StorageProviderCommands/Factories/RelationLookupCommandFactory.cs
@@ -82,7 +82,7 @@ public virtual IStorageProviderCommand<IEnumerable<DataContainer>, IRdbmsProvide
       ArgumentUtility.CheckNotNull("foreignKeyValue", foreignKeyValue);
 
       return InlineRdbmsStorageEntityDefinitionVisitor.Visit<IStorageProviderCommand<IEnumerable<DataContainer>, IRdbmsProviderCommandExecutionContext>>(
-          _rdbmsPersistenceModelProvider.GetEntityDefinition(foreignKeyEndPoint.ClassDefinition),
+          _rdbmsPersistenceModelProvider.GetEntityDefinition(foreignKeyEndPoint.TypeDefinition),
           (table, continuation) => CreateForDirectRelationLookup(table, foreignKeyEndPoint, foreignKeyValue, sortExpressionDefinition),
           (filterView, continuation) => continuation(filterView.BaseEntity),
           (unionView, continuation) => CreateForIndirectRelationLookup(unionView, foreignKeyEndPoint, foreignKeyValue, sortExpressionDefinition),
diff --git a/Remotion/Data/DomainObjects/Persistence/StorageEntityBasedStorageProviderDefinitionFinder.cs b/Remotion/Data/DomainObjects/Persistence/StorageEntityBasedStorageProviderDefinitionFinder.cs
index a5b94aa58d..af1b23721f 100644
--- a/Remotion/Data/DomainObjects/Persistence/StorageEntityBasedStorageProviderDefinitionFinder.cs
+++ b/Remotion/Data/DomainObjects/Persistence/StorageEntityBasedStorageProviderDefinitionFinder.cs
@@ -22,19 +22,19 @@
 namespace Remotion.Data.DomainObjects.Persistence
 {
   /// <summary>
-  /// Returns the <see cref="StorageProviderDefinition"/> of a <see cref="ClassDefinition"/> based on its 
-  /// <see cref="ClassDefinition.StorageEntityDefinition"/>.
+  /// Returns the <see cref="StorageProviderDefinition"/> of a <see cref="TypeDefinition"/> based on its 
+  /// <see cref="TypeDefinition.StorageEntityDefinition"/>.
   /// </summary>
   public class StorageEntityBasedStorageProviderDefinitionFinder : IStorageProviderDefinitionFinder
   {
-    public StorageProviderDefinition GetStorageProviderDefinition (ClassDefinition classDefinition, string? errorMessageContext)
+    public StorageProviderDefinition GetStorageProviderDefinition (TypeDefinition typeDefinition, string? errorMessageContext)
     {
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
 
-      if (!classDefinition.HasStorageEntityDefinitionBeenSet)
-        throw new InvalidOperationException("Cannot obtain storage provider for ClassDefinitions without storage entities. " + errorMessageContext);
+      if (!typeDefinition.HasStorageEntityDefinitionBeenSet)
+        throw new InvalidOperationException("Cannot obtain storage provider for TypeDefinitions without storage entities. " + errorMessageContext);
 
-      return classDefinition.StorageEntityDefinition.StorageProviderDefinition;
+      return typeDefinition.StorageEntityDefinition.StorageProviderDefinition;
     }
   }
 }
diff --git a/Remotion/Data/DomainObjects/Queries/EagerFetching/FetchedRelationDataRegistrationAgentBase.cs b/Remotion/Data/DomainObjects/Queries/EagerFetching/FetchedRelationDataRegistrationAgentBase.cs
index 01d4d1b83b..803856e227 100644
--- a/Remotion/Data/DomainObjects/Queries/EagerFetching/FetchedRelationDataRegistrationAgentBase.cs
+++ b/Remotion/Data/DomainObjects/Queries/EagerFetching/FetchedRelationDataRegistrationAgentBase.cs
@@ -20,6 +20,7 @@
 using Remotion.Data.DomainObjects.DataManagement;
 using Remotion.Data.DomainObjects.Infrastructure.ObjectPersistence;
 using Remotion.Data.DomainObjects.Mapping;
+using Remotion.Reflection;
 using Remotion.Utilities;
 
 namespace Remotion.Data.DomainObjects.Queries.EagerFetching
@@ -72,19 +73,16 @@ private void CheckClassDefinitionOfOriginatingObject (IRelationEndPointDefinitio
       Assertion.DebugAssert(originatingObject.IsNull == false, "originatingObject.IsNull == false");
       Assertion.DebugIsNotNull(originatingObject.ObjectID, "originatingObject.ObjectID != null");
 
-      var relationEndPointDefinitionInheritanceRoot = relationEndPointDefinition.ClassDefinition.GetInheritanceRootClass();
-      var originatingObjectInheritanceRoot = originatingObject.ObjectID.ClassDefinition.GetInheritanceRootClass();
-
-      if (ReferenceEquals(relationEndPointDefinitionInheritanceRoot, originatingObjectInheritanceRoot))
+      if (TypeDefinitionHierarchy.ArePartOfSameHierarchy(relationEndPointDefinition.TypeDefinition, originatingObject.ObjectID.ClassDefinition))
         return;
 
       var message = string.Format(
           "Cannot register relation end-point '{0}' for domain object '{1}'. The end-point belongs to an object of "
-          + "class '{2}' but the domain object has class '{3}'.",
+          + "type '{2}' but the domain object has type '{3}'.",
           relationEndPointDefinition.PropertyName,
           originatingObject.ObjectID,
-          relationEndPointDefinition.ClassDefinition.ID,
-          originatingObject.ObjectID.ClassDefinition.ID);
+          relationEndPointDefinition.TypeDefinition.Type.GetFullNameSafe(),
+          originatingObject.ObjectID.ClassDefinition.Type.GetFullNameSafe());
 
       throw new InvalidOperationException(message);
     }
@@ -98,14 +96,13 @@ private void CheckClassDefinitionOfRelatedObject (
       ArgumentUtility.CheckNotNull("oppositeEndPointDefinition", oppositeEndPointDefinition);
       ArgumentUtility.CheckNotNull("relatedObjectID", relatedObjectID);
 
-
-      if (!oppositeEndPointDefinition.ClassDefinition.IsSameOrBaseClassOf(relatedObjectID.ClassDefinition))
+      if (!oppositeEndPointDefinition.TypeDefinition.IsAssignableFrom(relatedObjectID.ClassDefinition))
       {
         var message = string.Format(
             "Cannot associate object '{0}' with the relation end-point '{1}'. An object of type '{2}' was expected.",
             relatedObjectID,
             relationEndPointDefinition.PropertyName,
-            oppositeEndPointDefinition.ClassDefinition.ClassType);
+            oppositeEndPointDefinition.TypeDefinition.Type);
 
         throw new InvalidOperationException(message);
       }
diff --git a/Remotion/Data/DomainObjects/Queries/QueryFactory.cs b/Remotion/Data/DomainObjects/Queries/QueryFactory.cs
index ba9239262d..766d7cd9b5 100644
--- a/Remotion/Data/DomainObjects/Queries/QueryFactory.cs
+++ b/Remotion/Data/DomainObjects/Queries/QueryFactory.cs
@@ -63,8 +63,8 @@ public static class QueryFactory
     public static IQueryable<T> CreateLinqQuery<T> ()
         where T: DomainObject
     {
-      var startingClassDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(T));
-      var providerDefinition = startingClassDefinition.StorageEntityDefinition.StorageProviderDefinition;
+      var startingTypeDefinition = MappingConfiguration.Current.GetTypeDefinition(typeof(T));
+      var providerDefinition = startingTypeDefinition.StorageEntityDefinition.StorageProviderDefinition;
 
       var executor = s_linqProviderComponentFactory.Value.CreateQueryExecutor(providerDefinition);
       return CreateLinqQuery<T>(s_queryParser.Value, executor);
diff --git a/Remotion/Data/DomainObjects/ReflectionUtility.cs b/Remotion/Data/DomainObjects/ReflectionUtility.cs
index 1951fce6e4..cb0889ac21 100644
--- a/Remotion/Data/DomainObjects/ReflectionUtility.cs
+++ b/Remotion/Data/DomainObjects/ReflectionUtility.cs
@@ -374,12 +374,15 @@ internal static bool IsTypePropertyValueType (Type propertyType)
     /// Gets the declaring domain object type for the given property.
     /// </summary>
     /// <param name="propertyInfo">The <see cref="IPropertyInformation"/> to analyze.</param>
-    /// <param name="classDefinition">The <see cref="ClassDefinition"/> of the given <see cref="IPropertyInformation"/></param>
+    /// <param name="typeDefinition"></param>
     /// <returns>the declaring domain object type for the given property.</returns>
-    public static Type GetDeclaringDomainObjectTypeForProperty (IPropertyInformation propertyInfo, ClassDefinition classDefinition)
+    public static Type GetDeclaringDomainObjectTypeForProperty (IPropertyInformation propertyInfo, TypeDefinition typeDefinition)
     {
       ArgumentUtility.CheckNotNull("propertyInfo", propertyInfo);
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
+
+      if (typeDefinition is not ClassDefinition classDefinition)
+        return propertyInfo.DeclaringType!.ConvertToRuntimeType();
 
       var persistentMixin = GetPersistentMixinTypeForProperty(propertyInfo, classDefinition);
       if (persistentMixin != null)
@@ -396,15 +399,18 @@ public static Type GetDeclaringDomainObjectTypeForProperty (IPropertyInformation
     }
 
     /// <summary>
-    /// Checks if the given <see cref="PropertyInfo"/> on the given <see cref="ClassDefinition"/> is a mixed property.
+    /// Checks if the given <see cref="PropertyInfo"/> on the given <see cref="TypeDefinition"/> is a mixed property.
     /// </summary>
     /// <param name="propertyInfo">The <see cref="IPropertyInformation"/> to analyze.</param>
-    /// <param name="classDefinition">The <see cref="ClassDefinition"/> of the given <see cref="IPropertyInformation"/></param>
+    /// <param name="typeDefinition">The <see cref="TypeDefinition"/> of the given <see cref="IPropertyInformation"/></param>
     /// <returns><see langword="true" /> if the given <see cref="PropertyInfo"/> is a mixed property.</returns>
-    public static bool IsMixedProperty (IPropertyInformation propertyInfo, ClassDefinition classDefinition)
+    public static bool IsMixedProperty (IPropertyInformation propertyInfo, TypeDefinition typeDefinition)
     {
       ArgumentUtility.CheckNotNull("propertyInfo", propertyInfo);
-      ArgumentUtility.CheckNotNull("classDefinition", classDefinition);
+      ArgumentUtility.CheckNotNull("typeDefinition", typeDefinition);
+
+      if (typeDefinition is not ClassDefinition classDefinition)
+        return false;
 
       return GetPersistentMixinTypeForProperty(propertyInfo, classDefinition) != null;
     }
diff --git a/test.diff b/test.diff
new file mode 100644
index 0000000000..8a67ab0e5a
Binary files /dev/null and b/test.diff differ