[Zope] - difference between AUTHENTICATED_USER and REMOTE_USER

Hi there - I was wondering, what's the difference between the DTML variables AUTHENTICATED_USER (defined by Zope) and REMOTE_USER (listed in the DTML guide as a CGI-defined request variable. If AUTHENTICATED_USER is defined in a given page, it seems like REMOTE_USER should also be defined - however, when I do something like <!--#if AUTHENTICATED_USER--> <!--#var REQUEST--> <!--#/if--> REQUEST contains a lot of stuff but not REMOTE_USER. Am I misunderstanding the meaning of this variable? (the reason I want to do this is, I want to use the name of the remote user as a parameter for a database access; there must be a good way to do this) --Brian