[Zope] Returning sequences of values with External Methods

Currently, I am making a lot of external methods, and I would like to use one like this: <dtml-in methodname>   <dtml-var foo> <dtml-var bar> </dtml-in> So basicly, I want to return a list of named values (a dist of dictionaries)? Are there any pittfalls you guys can see in doing this? suggestions? Should I make it a Product?