[Zope-dev] Reference to a user

Hopefully this will be a little simpler ;-) If I want to store a reference to a User in Zope, what's the best way to do it? I'm currently storing just the user's name, which doesn't seem very robust. Perhaps there's a more conrete reference to the user object? How about a path or something? Is there an interface for this anywhere? I guess something would have been needed for the ownership stuff? Any ideas gratefully recieved :-) cheers, Chris