RE: Who needs and uses XML Schema key/keyref?

["Arnold, Curt" <Curt.Arnold@hyprotech.com>]

If you were trying to simplify the implementation of schema processors by eliminating XPath, you would have to throw out <xsd:unique> also.

If you have to have XPath in schema, I would suggest that it be made useful by adding an <xsd:prohibit> or <xsd:check> constraint (see
http://lists.w3.org/Archives/Public/www-xml-schema-comments/2000JulSep/0010.html).  It appears that you are able to write kludgy <xsd:unique> constraints that effectively prohibit a specific pattern,
such as attribute cocurrence.  Since that was an oft requested feature, if it can be kludged it with uniques, we could give rise to our own equivalent of 1-pixel GIF's.