diff --git a/object/service.proto b/object/service.proto
index 762d12f..810793b 100644
--- a/object/service.proto
+++ b/object/service.proto
@@ -615,7 +615,9 @@ message SearchV2Response {
   neo.fs.v2.session.ResponseVerificationHeader verify_header = 3;
 }
 
-// Object payload range. Ranges of zero length SHOULD be considered as invalid.
+// Object payload range. Ranges of zero length SHOULD be considered as invalid
+// except for the special 0:0 request which is interpreted as "get whole
+// payload" and allows to receive payload only when its size is not known.
 message Range {
   // Offset of the range from the object payload start
   uint64 offset = 1;
diff --git a/proto-docs/object.md b/proto-docs/object.md
index 948e923..080b546 100644
--- a/proto-docs/object.md
+++ b/proto-docs/object.md
@@ -723,7 +723,9 @@ PUT Object response body
 <a name="neo.fs.v2.object.Range"></a>
 
 ### Message Range
-Object payload range. Ranges of zero length SHOULD be considered as invalid.
+Object payload range. Ranges of zero length SHOULD be considered as invalid
+except for the special 0:0 request which is interpreted as "get whole
+payload" and allows to receive payload only when its size is not known.
 
 
 | Field | Type | Label | Description |