diff --git a/src/bold/boldediting.js b/src/bold/boldediting.js
index 50f61e1..40602c4 100644
--- a/src/bold/boldediting.js
+++ b/src/bold/boldediting.js
@@ -28,7 +28,10 @@ export default class BoldEditing extends Plugin {
 		const editor = this.editor;
 		// Allow bold attribute on text nodes.
 		editor.model.schema.extend( '$text', { allowAttributes: BOLD } );
-		editor.model.schema.setAttributeProperties( BOLD, { isFormatting: true } );
+		editor.model.schema.setAttributeProperties( BOLD, {
+			isFormatting: true,
+			copyOnEnter: true
+		} );
 
 		// Build converter from model to view for data and editing pipelines.
 
diff --git a/src/code/codeediting.js b/src/code/codeediting.js
index ecda4ed..334b5df 100644
--- a/src/code/codeediting.js
+++ b/src/code/codeediting.js
@@ -29,7 +29,10 @@ export default class CodeEditing extends Plugin {
 
 		// Allow code attribute on text nodes.
 		editor.model.schema.extend( '$text', { allowAttributes: CODE } );
-		editor.model.schema.setAttributeProperties( CODE, { isFormatting: true } );
+		editor.model.schema.setAttributeProperties( CODE, {
+			isFormatting: true,
+			copyOnEnter: true
+		} );
 
 		editor.conversion.attributeToElement( {
 			model: CODE,
diff --git a/src/italic/italicediting.js b/src/italic/italicediting.js
index 8161720..607499e 100644
--- a/src/italic/italicediting.js
+++ b/src/italic/italicediting.js
@@ -29,7 +29,10 @@ export default class ItalicEditing extends Plugin {
 
 		// Allow italic attribute on text nodes.
 		editor.model.schema.extend( '$text', { allowAttributes: ITALIC } );
-		editor.model.schema.setAttributeProperties( ITALIC, { isFormatting: true } );
+		editor.model.schema.setAttributeProperties( ITALIC, {
+			isFormatting: true,
+			copyOnEnter: true
+		} );
 
 		editor.conversion.attributeToElement( {
 			model: ITALIC,
diff --git a/src/strikethrough/strikethroughediting.js b/src/strikethrough/strikethroughediting.js
index d398d48..7514a53 100644
--- a/src/strikethrough/strikethroughediting.js
+++ b/src/strikethrough/strikethroughediting.js
@@ -30,7 +30,10 @@ export default class StrikethroughEditing extends Plugin {
 
 		// Allow strikethrough attribute on text nodes.
 		editor.model.schema.extend( '$text', { allowAttributes: STRIKETHROUGH } );
-		editor.model.schema.setAttributeProperties( STRIKETHROUGH, { isFormatting: true } );
+		editor.model.schema.setAttributeProperties( STRIKETHROUGH, {
+			isFormatting: true,
+			copyOnEnter: true
+		} );
 
 		editor.conversion.attributeToElement( {
 			model: STRIKETHROUGH,
diff --git a/src/subscript/subscriptediting.js b/src/subscript/subscriptediting.js
index 21ffab8..a23ea68 100644
--- a/src/subscript/subscriptediting.js
+++ b/src/subscript/subscriptediting.js
@@ -28,7 +28,10 @@ export default class SubscriptEditing extends Plugin {
 		const editor = this.editor;
 		// Allow sub attribute on text nodes.
 		editor.model.schema.extend( '$text', { allowAttributes: SUBSCRIPT } );
-		editor.model.schema.setAttributeProperties( SUBSCRIPT, { isFormatting: true } );
+		editor.model.schema.setAttributeProperties( SUBSCRIPT, {
+			isFormatting: true,
+			copyOnEnter: true
+		} );
 
 		// Build converter from model to view for data and editing pipelines.
 
diff --git a/src/superscript/superscriptediting.js b/src/superscript/superscriptediting.js
index 7e6c02e..1ce5768 100644
--- a/src/superscript/superscriptediting.js
+++ b/src/superscript/superscriptediting.js
@@ -28,7 +28,10 @@ export default class SuperscriptEditing extends Plugin {
 		const editor = this.editor;
 		// Allow super attribute on text nodes.
 		editor.model.schema.extend( '$text', { allowAttributes: SUPERSCRIPT } );
-		editor.model.schema.setAttributeProperties( SUPERSCRIPT, { isFormatting: true } );
+		editor.model.schema.setAttributeProperties( SUPERSCRIPT, {
+			isFormatting: true,
+			copyOnEnter: true
+		} );
 
 		// Build converter from model to view for data and editing pipelines.
 
diff --git a/src/underline/underlineediting.js b/src/underline/underlineediting.js
index c8e8aef..f00fc51 100644
--- a/src/underline/underlineediting.js
+++ b/src/underline/underlineediting.js
@@ -29,7 +29,10 @@ export default class UnderlineEditing extends Plugin {
 
 		// Allow strikethrough attribute on text nodes.
 		editor.model.schema.extend( '$text', { allowAttributes: UNDERLINE } );
-		editor.model.schema.setAttributeProperties( UNDERLINE, { isFormatting: true } );
+		editor.model.schema.setAttributeProperties( UNDERLINE, {
+			isFormatting: true,
+			copyOnEnter: true
+		} );
 
 		editor.conversion.attributeToElement( {
 			model: UNDERLINE,
diff --git a/tests/bold/boldediting.js b/tests/bold/boldediting.js
index 5e5bb5a..91d3f5c 100644
--- a/tests/bold/boldediting.js
+++ b/tests/bold/boldediting.js
@@ -41,11 +41,17 @@ describe( 'BoldEditing', () => {
 	} );
 
 	it( 'should be marked with a formatting property', () => {
-		expect( model.schema.getAttributeProperties( 'bold' ) ).to.deep.equal( {
+		expect( model.schema.getAttributeProperties( 'bold' ) ).to.include( {
 			isFormatting: true
 		} );
 	} );
 
+	it( 'its attribute is marked with a copOnEnter property', () => {
+		expect( model.schema.getAttributeProperties( 'bold' ) ).to.include( {
+			copyOnEnter: true
+		} );
+	} );
+
 	it( 'should set editor keystroke', () => {
 		const spy = sinon.spy( editor, 'execute' );
 		const keyEventData = {
diff --git a/tests/code/codeediting.js b/tests/code/codeediting.js
index 33b968d..6723357 100644
--- a/tests/code/codeediting.js
+++ b/tests/code/codeediting.js
@@ -40,11 +40,17 @@ describe( 'CodeEditing', () => {
 	} );
 
 	it( 'should be marked with a formatting property', () => {
-		expect( model.schema.getAttributeProperties( 'code' ) ).to.deep.equal( {
+		expect( model.schema.getAttributeProperties( 'code' ) ).to.include( {
 			isFormatting: true
 		} );
 	} );
 
+	it( 'its attribute is marked with a copOnEnter property', () => {
+		expect( model.schema.getAttributeProperties( 'code' ) ).to.include( {
+			copyOnEnter: true
+		} );
+	} );
+
 	describe( 'command', () => {
 		it( 'should register code command', () => {
 			const command = editor.commands.get( 'code' );
diff --git a/tests/italic/italicediting.js b/tests/italic/italicediting.js
index 5b9f1a5..3ed018a 100644
--- a/tests/italic/italicediting.js
+++ b/tests/italic/italicediting.js
@@ -40,11 +40,17 @@ describe( 'ItalicEditing', () => {
 	} );
 
 	it( 'should be marked with a formatting property', () => {
-		expect( model.schema.getAttributeProperties( 'italic' ) ).to.deep.equal( {
+		expect( model.schema.getAttributeProperties( 'italic' ) ).to.include( {
 			isFormatting: true
 		} );
 	} );
 
+	it( 'its attribute is marked with a copOnEnter property', () => {
+		expect( model.schema.getAttributeProperties( 'italic' ) ).to.include( {
+			copyOnEnter: true
+		} );
+	} );
+
 	describe( 'command', () => {
 		it( 'should register italic command', () => {
 			const command = editor.commands.get( 'italic' );
diff --git a/tests/strikethrough/strikethroughediting.js b/tests/strikethrough/strikethroughediting.js
index c2d39a9..3b89366 100644
--- a/tests/strikethrough/strikethroughediting.js
+++ b/tests/strikethrough/strikethroughediting.js
@@ -40,11 +40,17 @@ describe( 'StrikethroughEditing', () => {
 	} );
 
 	it( 'should be marked with a formatting property', () => {
-		expect( model.schema.getAttributeProperties( 'strikethrough' ) ).to.deep.equal( {
+		expect( model.schema.getAttributeProperties( 'strikethrough' ) ).to.include( {
 			isFormatting: true
 		} );
 	} );
 
+	it( 'its attribute is marked with a copOnEnter property', () => {
+		expect( model.schema.getAttributeProperties( 'strikethrough' ) ).to.include( {
+			copyOnEnter: true
+		} );
+	} );
+
 	describe( 'command', () => {
 		it( 'should register strikethrough command', () => {
 			const command = editor.commands.get( 'strikethrough' );
diff --git a/tests/subscript/subscriptediting.js b/tests/subscript/subscriptediting.js
index 86a58f7..29c90a9 100644
--- a/tests/subscript/subscriptediting.js
+++ b/tests/subscript/subscriptediting.js
@@ -40,11 +40,17 @@ describe( 'SubEditing', () => {
 	} );
 
 	it( 'should be marked with a formatting property', () => {
-		expect( model.schema.getAttributeProperties( 'subscript' ) ).to.deep.equal( {
+		expect( model.schema.getAttributeProperties( 'subscript' ) ).to.include( {
 			isFormatting: true
 		} );
 	} );
 
+	it( 'its attribute is marked with a copOnEnter property', () => {
+		expect( model.schema.getAttributeProperties( 'subscript' ) ).to.include( {
+			copyOnEnter: true
+		} );
+	} );
+
 	describe( 'command', () => {
 		it( 'should register subscript command', () => {
 			const command = editor.commands.get( 'subscript' );
diff --git a/tests/superscript/superscriptediting.js b/tests/superscript/superscriptediting.js
index e0da6ba..132b491 100644
--- a/tests/superscript/superscriptediting.js
+++ b/tests/superscript/superscriptediting.js
@@ -40,11 +40,17 @@ describe( 'SuperEditing', () => {
 	} );
 
 	it( 'should be marked with a formatting property', () => {
-		expect( model.schema.getAttributeProperties( 'superscript' ) ).to.deep.equal( {
+		expect( model.schema.getAttributeProperties( 'superscript' ) ).to.include( {
 			isFormatting: true
 		} );
 	} );
 
+	it( 'its attribute is marked with a copOnEnter property', () => {
+		expect( model.schema.getAttributeProperties( 'superscript' ) ).to.include( {
+			copyOnEnter: true
+		} );
+	} );
+
 	describe( 'command', () => {
 		it( 'should register superscript command', () => {
 			const command = editor.commands.get( 'superscript' );
diff --git a/tests/underline/underlineediting.js b/tests/underline/underlineediting.js
index 548c5ce..61f3c1f 100644
--- a/tests/underline/underlineediting.js
+++ b/tests/underline/underlineediting.js
@@ -40,11 +40,17 @@ describe( 'UnderlineEditing', () => {
 	} );
 
 	it( 'should be marked with a formatting property', () => {
-		expect( model.schema.getAttributeProperties( 'underline' ) ).to.deep.equal( {
+		expect( model.schema.getAttributeProperties( 'underline' ) ).to.include( {
 			isFormatting: true
 		} );
 	} );
 
+	it( 'its attribute is marked with a copOnEnter property', () => {
+		expect( model.schema.getAttributeProperties( 'underline' ) ).to.include( {
+			copyOnEnter: true
+		} );
+	} );
+
 	describe( 'command', () => {
 		it( 'should register underline command', () => {
 			const command = editor.commands.get( 'underline' );