Regarding issue CORE-44, "id" attribute specification, it seems
that current best practice is to reference the xml: namespace
(http://www.w3.org/XML/1998/namespace), which now defines an xml:id
attribute. Its specification is found in
http://www.w3.org/TR/xml-id/, "xml:id Version 1.0", W3C Recommendation
9 September 2005.
Prior to this, schema authors were required to define such
an attribute within their own namespaces (e.g. eb:id in ebMS 2.0,
wsu:Id in WS-Security).
--Pete
Pete Wenzel