[Zope] CookieUserFolder - how to force a logout

Hi, I'm trying to figure out how to logout a user with CookieUserFolder. Can someone provide an example of using a link to logout a user? I'd like to add this to standard_html_header. Looks like a great tool, but the docs are a bit sparse for my limited knowledge. (That's my problem, not the authors). An example would be helpful. This would be a great addition to the Zope core! I'll keep looking at the code and post an example if I figure it out ;-) Thanks, Mark