RE: [xml-dev] Substitution Groups - Use 'em or lose 'em?

I'm glad I looked through my xml-dev folder before resuming work on my XML
2005 paper... can anyone point me to a well-known, shared (e.g. "industry
standard" for some industry or another) XSD schema that uses substitution
groups to make local customization of the schema easier? 

thanks,

Bob DuCharme   www.snee.com/bob       <bob@  
snee.com> weblog on linking-related topics: 
http://www.oreillynet.com/pub/au/1191