[ZPT] Newbie: Calling REQUEST.set from zpt ?

[Gitte Wange]

Hello,

I'm new into zpt but it looks like a very nice way in designing skins
for Zope.
I have understood the basics and have already created a new skin for
CMF.
Now I have run into a small problem I can't seem to read about in any of
the howto's I have been reading:
How do I call REQUEST.set() ?
The problem is this:
I have a pt which needs to display some data from the object in context.
But this object can be of 2 metatypes; either it's a Clip or a
Masterfile.
In dtml I would do somthing like:
<dtml-if "this().meta_type == 'Media Manager Master File'">
 <dtml-call "REQUEST.set('fileobj', this()">
<dtml-else>
 <dtml-call "REQUEST.set('fileobj', this().getMasterfile())">
</dtml-if>
<table>
 <tr>
  <td><dtml-var "fileobj.title"></td>
 </tr>
</table>

But how to do this in ZPT ???

TIA,
Gitte Wange