Schema Versioning - A stylesheet to implement backward

Suppose  an XML Schema issued to our business partners is updated with
new elements but we want to continue to accept XML that conforms to
old schema.

Provided that the elements from the old schema are a subset of the
elements in the new schema this can be done with a transformation.

I have written a stylesheet that takes an XML Schema call it
old-schema as a parameter and given xml conformant to the new schema
derives an xml instance that is conformant to old schema .

I believe this to be a generically useful solution and would like some
suggestions as to where to publish the code - I was thinking EXSLT but
have never done anything like this before and am not sure it is the
right forum.