See the thread that I started at xmlschema-dev mailing list: http://lists.w3.org/Archives/Public/xmlschema-dev/2007Jul/0001.html
I also saw a bug report related to some of my concerns reported as [Bug 4838] Chameleon
I did not get a clear understanding of the issues that I raised.
I do understand that:
- circular dependencies is OK
I also still do not understand the semantics of referencing names beyond the bounds of the same schema document as far as schema composition is involved. Should xsd:any and ref consider only names defined in the same schema document and in schema documents that are imported and included in it? Or perhaps should xsd:any and ref consider only names in the same schema document and in schema documents that import or include the schema document that they appear in? Or perhaps both? What exactly are the rules? I cannot make them out from the standard.
Not that it helps me, but it is still interesting to see the list of reported bugs to XML Schema when you look for "schema composition" in the bug tracking system: http://www.w3.org/Bugs/Public/buglist.cgi?query_format=specific&order=relevance+desc&bug_status=__open__&product=XML+Schema&content=schema+composition