Regarding the upcoming Zope Book: There are some examples for UniqueValuesFor method and "_usage" syntax (it looks that only values "range:min", "range:max" and "range:min:max" are possible), but these are not mentioned in the DTML reference or API reference. Maybe Zope Book needs a ZCatalog reference, if there are methods like UniqueValuesFor... I would recommend that since the current Zope Book is a giant leap forward, these and any other language tricks that are scattered in the Zope Book chapters should be briefly mentioned in the ZopeBook DTML and API references. IMHO there are many people like me who: - are trying to start using Zope BECAUSE OF the final availability of Zope Book - for various reasons are not very comfortable with hunting information around zope.org and in Zope sources (no permanent internet connection is a strong reason) - consequently expect to find all basic information in coherent form in Zope Book Obviously, Zope Book can't contain everything. I like the sentence "this is an advanced topic and it's outside the scope of this book". Authors have put limits to what they want to achieve. I wish that the ZB is coherent in the "explanation - example - reference" trio. -- Milos Prudek