NZ help required re XCIL (message picked from xml.org)

[colin.wallis@ssc.govt.nz]

Hi,

I'm working on an application where I need to use subsets of publicly available schemas.

For instance, to model contacts information I'm using xCIL however xCIL has a very large range of formats, for instance one of the immediate children the CustomerDetails element can be either OrganisationInfo or 
PersonInfo. My system, however, only wants to process PersonInfo elements and never OrganisationInfo so, do I -

a) create a more specific schema using the xCIL namespace (!) (if so, should I then validate it twice - once against xCIL and then against my more specific schema)

b) XML.com has this article - Designing a New Schema with XML Design Patterns - http://www.xml.com/pub/a/2003/06/04/patterns.html - which would seem to suggest selectively reusing types and global elements from other namespaces, are there any problems with this approach?

c) is the schema just a contract and I should use something else again for validation?

Is this a dumb question or has anybody else come across this issue and if so how have they approached it?

Cheers,

Fraser