[Zope-dev] Allowing only specific meta_types to be addable to my product

I have created a Product made up of hundreds of classes. Each class has restrictions that should only allow a certain few meta_types to be added. I have tried every method I can find to do this, without luck. I know you can restrict this in a ZClass by defining the addable subobjects. However, I cannot determine how to do this in the python class. Only those meta_types allowed should appear in the Add Drop down list. Thanks in advance, Stacy