XML Schema for RDF

$Id: rdf.xsd,v 1.17 2000/08/04 14:37:44 swick Exp $

originally derived from Rick J's work: 

			    From:      Rick JELLIFFE <ricko@allette.com.au>
			    To:        xml-dev@xml.org
			    Subject:   Re: new public working draft of XML Schema
			    Date:      Sat, 26 Feb 2000 23:05:20 +0800

then modified to match the RDF formal grammar

created 2000-12-25,
Rick Jelliffe,
Academia Sinica Computing Centre.
Thanks to Henry Thompson for help.

RDF Specification at W3C.

Later, taken from http://www.w3.org/2001/XMLSchema and updated

 this is a "union type"; use xsi:type in the instance to discriminate between concrete subtypes this is a "union type"; use xsi:type in the instance to discriminate between concrete subtypes. @@hmm... can I mark this as "abstract" somehow?