[Zope] Unclear about factory 'Add list name'

Can someone tell me what's the relation between 'Add list name" in the factory of the zclass and the MetaType-field in the "basic" tab of the zclass? Pointer to documentation would be okay, I couldn't find one. All I know is the if the two are different that cut&paste won't work anymore. The documentation in zope's online help didn't mention this fact "Add list name: The name that will appear on the in the product add list. In the case of ZClasses this is normally the ZClass's meta-type." and "Meta type: The name of the ZClass as it appears in the product add list." Is there a use in the possibility to use another "Add list name" in the factory? cheers, oliver