XML Schema and XPointer

Hello,

I have an XML Schema that represents some sort of a lexicon.
In this lexicon there are items which can be referred using an ID.

I am now defining another XML Schema and need to express a method of pointing
to an item in a lexicon (that is written in an instance of this lexicon
schema).

What would be a good way to point there and still get some sort of validation
and enforcement from an XML Parser?

For example, would XPointer be a good solution?
If so, how to represent it in the XSD? And how to represent it in the XML
instance?


Thanks.

-- 
Shlomo Yona

http://cs.haifa.ac.il/~shlomo/