I would like to restrict the types of objects (from a python-based product) that may be placed in Folders, or any other dumb container, based on certain conditions. For example: I'd like to restrict the number of a certain type of object that may appear in a folder. The end-user can add up to the limit, and afterwards the object type should NO LONGER APPEAR in the "Add List". I've thought about building a specialized folder, but I'd rather not. Zope already has a good folder with all the things I need. What Zope 2.4+ really needs to do is callback a provided function to determine if a particular class is allowed in a specified container instance (or class) Using the "implements" parameter of the registerClass method is not enough as it only permits static checking. Any help would be greatly appreciated. Regards -- Brian _________________________________________________________________ Send and receive Hotmail on your mobile device: http://mobile.msn.com