[Zope] getRoot() how?

In a product class I want to add a method that returns the root of the instance. Suppose I have this URL: http://localhost:8080/myProductInstance/subfolder/foldersub/useRoot() Method useRoot() will get the 'myProductInstance' object and add some properties to it. To do this you would do: root_instance = self.myProductInstance But I can't know the name of the instance of course. This would be another method: root_instance = self.superValues('Product Meta Type')[0] Neither method is very neat. Is there a OO command to immediatly get the root of the instance? Peter