[Zope] dtml images and property sheets

[Thomas]

I have a text field in my property sheet where some text is inputted.  I want 
to be write in that text field something like this:

<dtml-var myimage> 

and thus call an image within that Zclass instance's namespace.  Seems like
dtml won't work here.  I am missing something?  Any tips or hints appreciated.

Thanks,
Thomas