[Zope] inserting or modifying REQUEST.form objects ???

Can objects be added to or modified in the REQUEST.form? I can add/modify objects in REQUEST as in: expr="REQUEST.set('myVar',3)" but I can't seem to do this for the REQUEST.form dictionary... expr="REQUEST.form.set('myVar',3)" <- error expr="REQUEST.form['myVar']=3" <- error Neither the DTML-like or Python-like syntax seems to work. ..is there some syntax which can modify (in place) or add things to REQUEST.form? Is REQUEST.form READ-ONLY for some reason? ------------ Brian Withun