[Zope-dev] define restricted list of meta types for subobjects

hi i made a folderish product which inherits from objectmanager to define which meta_types the user should be able to put into it i have overriden "all_meta_types" from objectmanager now only those returned from this function are displayed in the product add list in the ZMI but i can still add other subobjects when i play with the url and call the addform directly. my q: is there a method to define this subobjects via permissions without setting permissions each time a product class is instanciated i read about some "permission key" for a specific meta type. but i want to set the permissions only for a specific product, independend of the instances location thx in advance, bernd