XSD ontology

Hi,

  I found it useful to put together a sketch of an XSD ontology for the Clerezza project http://incubator.apache.org/clerezza/

  Clerezza uses this ontology to create a Class of Java URIReferences, which can then be used in Java Programs quite nicely.

  But I can see this being very useful to a number of other projects. It seems that it should ideally be available at the xsd name space, though perhaps really as an RDFa document.

  Perhaps this can be useful to others, and if you find improvements, or mistakes, please let me know.

	Henry