Re: conditional expression

Requests for this or similar function are made regularly.  As I have 
mentioned on this list before, the XML Schema WG is working hard on 
proposals for features that would provide for expressing such constraints 
in the upcoming version of the XML Schema Language, i.e. XML Schema 1.1. 
If you're interested, look for features in upcoming working drafts that 
allow you to express "co-occurrence constraints". 

Noah

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Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
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