On May 18, 2008, at 11:09 AM, h.b.furuseth(a)usit.uio.no wrote: Yes, A is implicitly present (by implicit add). This can be argued to be incorrect. It is improper to attempt to delete a superclass of any listed class. If provided by the client, yes. Otherwise A is implicitly present due to B. When a client adds B then deletes B, its a net zero result. If A were actually added by the server, the delete of B would either leave A behind or be invalid (such as when A is abstract). The RFCs are someone vague here. Adding A when a subclass is present is just as invalid as deleting A when a subclass is present. Both should result in errors.