The documentation/support for MT4/MTOS is somewhat lacking at the moment... this seems like a fairly simple problem to find an answer to, and yet with all my Google digging I haven't located anything. Here's what I'm trying to do...
<mt:SetVarBlock name="foo"><mt:EntryBasename></mt:SetVarBlock>
<h2><mt:Var name="foo" /></h2>
<mt:Assets tag="<mt:Var name="foo" />"> <mt:AssetURL><br/> </mt:Assets>
I'm basically trying to use an entry basename as a tag, then retrieve all the images that have that tag. The first mt:var call works fine... the proper name is printed correctly.
After that it goes awry... I never get a list of assets with the right tag name. I'm sure this is because I am not retrieving the variable properly and I'm not sure what is the right way since I haven't found any examples.
Is what I'm trying to do even possible with MTOS or are we stuck with static data for attribute values?
Thanks in advance.

This should be written like this:
I tried that, actually... but I get rebuild errors as a result.
An error occurred publishing entry 'September 24-28: DiGRA': Publish error in template 'Entry': Error in tag: You have an error in your 'tag' attribute: september2428digra
Not sure what this means... best guess is that I don't have any tags named "september2428digra"... but I had assumed that if there were no assets matching that particular tag, it would just return an empty list, rather than completely fall apart...