[Zope] Concepts

Is there a way to define a group in Zope? For instance, could I have user1, user2 and user3 as part of a group, say "testers", and the group "testers" can access to certain folders (or something of that sort) in Zope. I want users within a group to be able do updates on folders that group they belong to has been assigned to. Mixo Shiburi I have had a look at "roles", and what they seem to do is define permissions and not groups of people.