Hi Nick (please don't post HTML mail to the list). I *think* the "Include standard Zope persistent object base classes" check box gives your ZClass the "ZObject" interface which is similar to the SimpleItem interface (see the Zope API docs in the help system - I think it's under Help->Zope Help->API Documentation->ObjectManagerItem). As far as inheritance order, the first base class you add to the ZClass base class list will be ZObject if you use check the "standard base classes" checkbox. The next one will be the first base class you choose (the topmost), the next one will be the one under that, etc. -----Original Message----- From: Nick Trout [mailto:nick@videosystem.co.uk] Sent: Thursday, September 07, 2000 8:59 AM To: Zope Mail list Subject: [Zope] ZClass base classes I've looked all throught docs but I cant find anywhere an explanation of what properties the ZClass base classes give you. Also which order to inherit them, as the Developers Guide claims the order is important. Can anyone please enlighten me? Regards, Nick.