When trying to add an XML Document instance that has lower case id-attributes within tags (eg. something like <para id="p001">) Zope raises an exception (Error Value: Invalid or duplicate property id). But when the attribute is upper case, everything goes allright (<para ID="p001">). This time the XML-element instance has both a standard Zope id-property and an ID-property. Now maybe the XML parser that is used by Zope could be altered somewhat so that it translates to upper-case all occurences of an id-attribute. Hans van Mourik Electronic Text Centre Leiden <http://www.etcl.nl> ---example one:--- <?xml version="1.0"?> <article status="beta"> <section> <title>Sample document</title> <para ID="p001">foo</para> <para ID="p002">bar</para> </section> </article> ---example two (exception):--- <?xml version="1.0"?> <article status="beta"> <section> <title>Sample document</title> <para id="p001">foo</para> <para id="p002">bar</para> </section> </article>