[Zope] dtml-var behavior

I got a quoted version of the object if I made <dtml-var this> It does not evaluate the tags and quoted all < with < and so they all showed on the browser. What rules determine when it will be quoted? Also, I got the same result if I have <dtml-var "folder.obj"> I can work around with <dtml-with folder> <dtml-var obj> </dtml-with> But how can I workaround "this"? Rgs, Kent Sin