XML valued datatypes

Hi,

when we're talking about datatypes, what about xml value'd properties? 

Example:

You have two resources, one you PROPPATCHed with:

<?xml version="1.0" encoding="utf-8"?>
<D:propertyupdate xmlns:D="DAV:">
  <D:set>
    <D:prop xmlns:Z="http://www.w3.com/standards/z39.50">
      <Z:authors>
        <Z:Author>Jim Whitehead</Z:Author>
        <Z:Author>Roy Fielding</Z:Author>
        <Z:Co-author>Lieschen Mueller</Z:Co-author>
      </Z:authors>
    </D:prop>
  </D:set>
</D:propertyupdate>

the second with

<?xml version="1.0" encoding="utf-8"?>
<D:propertyupdate xmlns:D="DAV:">
  <D:set>
    <D:prop xmlns:Z="http://www.w3.com/standards/z39.50">
      <Z:authors>
        <Z:Author>Lieschen Mueller</Z:Author>
      </Z:authors>
    </D:prop>
  </D:set>
</D:propertyupdate>

How to find all resources, where Lieschen Mueller was author, not Co-author?
Currently you have to define something like:

<like>
  <prop>
    <Z:authors/>
  </prop>
  <literal>%Lieschen Mueller%</literal>
</like>

but of course you will find both resources. Relying on formatting won't
work. So what about something like:

<xpath>
  <prop>
    <Z:authors/>
  </prop>
  <literal>[Z:author="Lieschen Mueller"]</literal>
</xpath>

or finding all resources, where a Co-author is defined:

<xpath-is-defined>
  <prop>
    <Z:authors/>
  </prop>
  <literal>./Z:Co-author</literal>
</xpath-is-defined>

where the literal is an xpath expression relative to the property (root
element).

Regards,
Martin

__________________________
Martin Wallmer
Research & Development
Software AG    ++49 6151 92 1831
Uhlandstr. 12
D 64297 Darmstadt