Constraining a Schema

I am working with a schema that is purposely lax (i.e. it may allow too many occurrences, may contain irrelevant elements, etc.) so that it can handle a broad range of customer scenarios. I now have a customer that wants to constrain the schema such that only a subset of the functionality is available. This subset is expected to validate against its larger parent. I’ve come up with a number of different approaches to handle this:

1. Subset schema using available XML tooling. A standalone derivative will be produced.
2. Create a new schema, referencing the old one, but derive all the types by restriction.
3. Use XML Assertions
4. Use Schematron
5. Use CAMV

My preference is to use a XML Schema native approach (1-3), using XSD 1.0 only constructs if possible (1-2), as the actual used XML processor that gets used is outside my control.

Does anyone have ideas on a good approach?

John Dziurlaj

Elections Consultant

Hilton Roscoe LLC
Cell 330-714-8935 Work/Fax 234-706-6434