Well, it's true you can't embed a template inside a tag:
<foobar arg="blat">{{my template}}</foobar>
but you can work around it with the #tag parser function that converts tags into parser functions:
{{#tag:foobar | {{my template}} | arg=blat }}
which will do what you want....
DanB
-----Original Message----- Jim R. Wilson wrote:
Using templates within extension tags is next-to-impossible due to the order of operations during a page parse. If you want to be able to use template parameters, you should implement a Parser Function...