[Zope-dev] ZClass and ZCatalog

Hello Guys, I've a problem with a ZClass (JCEvent) I've created and ZCatalog. Base classes for JCEvent are: ZObject, JCObject, CatalogAwareBase. JCObject is another ZClass whose base class is ZObject. Instances of JCEvent are added to a ZCatalog but they are not automatically indexed by the catalog. The catalog is named 'events'. How can I automaticallly index them ? Thanks, - mn