Junk writes:

... searching on subobjects ... Implement a parameterless Python script that does the subobject magic.

Place it high in the Zope hierarchy, such that it is available by acquisition where it is needed. Use it as an index in your ZCatalog. More info: the Zope book or URL:http://www.dieter.handshake.de/pyprojects/zope/book/chap3.html Dieter