[Zope] CMFTopic problem, passing args in DTML, or just brain damage?

If I create a CMFTopic in the root called 'list', why does this work: http://servername.com/list?Subject=something ...giving me whatever my criterion is, narrowed by matching Subject='something' ...when calling the thing in DTML: list(_.None,_,Subject='something') doesn't seem to recognize the parameter? (and, I've tried many variations, wrapping with a dtml-with, passing 'list' instead of _ or _.None, passing a dict {'Subject':'something'}, all the same result) what am I missing?