[xml] Potential allowed elements at an element tree node

["Li Ning" <lining mail bitmate com>]

Dear freind,

I am going to develop a DTD guided XML file composer using libxml.
What I need is to let libxml tell me what kind of potential elements 
are allowed to insert at a particular XML element tree node according 
to DTD. I would be grateful to you if you can provide me a complete 
piece of code. Many thanks.

Ning Li