hierarchy

Hi!

I'm sort of new to the XML world, and I wonder whether it is possible to
implement hierarchy between XML entities.
I'm working in the web services context, and I would like to create a
service B (described by B.xml and B.xmls) deriving from a service A
(A.xml, A.xmls) and inheriting its characterisitcs (in the object
manner). Is it possible and how?

Thanks in advance!

Fabien.