XInclude and DOM

After a document has been processed via xinclude, how should xinclude nodes be handled in dom?
the origional xinclude elements remain in the document as XML_XINCLUDE_START and XML_XINCLUDE_END nodes, but are ignored when serializing. Should these be treated as standard ELEMENT nodes in regards to the object, methods and properties while navigating the processed tree?

Have not found any references to these node types and they arent part of the dom specs so really not sure how these should be handled.

Rob