[Zope] Advanced search with ZCatalog

Hi! I have a ZClass with several properties defined and indexed. Now I want to perform a search where the search term is matched against any of the properties. (So if I have say a title, summary and body property and my query term is "Test" any ZClass with Test in either title, summary ord body should be returned.) I've found some hints on this in the advanced search howto, that suggests performing multiple searches (one on each property) and concatenating the results. This seems rather clumsy and I wonder if there is any other possibility? Is there any documentation of the Catalog object? Can Catalog.searchResults() be of any use in this, and if so what's the meaning of its parameters? Regards, Markus