[support] Matching a term if it belongs to another term (views)

[Luke]

Another views question:

It would be convenient, if I could have a view match on a term argument, 
if the referenced TID was a child of another term.

So if TIDs 80 through 200 were children of TID 3, rather than coding for 
the range (which might get out of range TIDs added to it later), is there 
some way I could have the view check whether the passed argument of TID 
120, is in fact a child term of TID 3?

Hopefully that's not stupidly basic.

Luke