[Zope] special feature in DTML-TREE

[dsergent@imexpert.com]

Hi all,

I want to add a new feature in my dtml-tree tag.
In a few word I want to give parameter values in the url tree.
--> like this : http://blah?<my parameter>tree-e=....
but, in my parameter, in want to give dtml value like "REQUEST.Get('a')"


my problem is : how can I do this ? and In python how could I translate 
"REQUEST.get('a') in an explicit word ?"

thanks in advance !!!!