HI Gemini,
The best thing to do is to understand have work with XML. There is also the online tutorials, check these sites out:
http://www.programmingtutorials.com/tutorial.asp?id=XML http://www.w3schools.com/default.asp http://www.zvon.org/ Some questions would be in the context of:
What is XML? Why XML? What is the difference between XML and HTML? How is XML parsed? Can you name a few parsers? How do they work?
Questions about tag rules.
Questions about StyleSheets XSLT.
How do you display XML?
What is DTD?
What are namespaces and how to resolve conflicts.
Good luck!