Index: _source/core/htmlparser/element.js
===================================================================
--- _source/core/htmlparser/element.js	(revision 6241)
+++ _source/core/htmlparser/element.js	(revision )
@@ -36,9 +36,18 @@
 
 	var tagName = attributes[ 'data-cke-real-element-type' ] || name;
 
+	// Reveal the real semantic of our internal custom tag name (#6639).
+	var internalTag = tagName.match( /^cke:(.*)/ );
+  	internalTag && ( tagName = internalTag[ 1 ] );
+
 	var dtd			= CKEDITOR.dtd,
-		isBlockLike	= !!( dtd.$nonBodyContent[ tagName ] || dtd.$block[ tagName ] || dtd.$listItem[ tagName ] || dtd.$tableContent[ tagName ] || dtd.$nonEditable[ tagName ] || tagName == 'br' ),
+		isBlockLike	= !!( dtd.$nonBodyContent[ tagName ]
+				|| dtd.$block[ tagName ]
+				|| dtd.$listItem[ tagName ]
+				|| dtd.$tableContent[ tagName ]
+				|| dtd.$nonEditable[ tagName ]
+				|| tagName == 'br' ),
-		isEmpty		= !!dtd.$empty[ name ];
+		isEmpty = !!dtd.$empty[ name ];
 
 	this.isEmpty	= isEmpty;
 	this.isUnknown	= !dtd[ name ];