String manipulation with "this" object

I have a button within a movie clip that passes an identifier to a function like so:

on (release)

The function recieves “this” as “_level0.mc_main_menu.game0”

I want to treat the returned value as a string & get the value “game0” from it.

How do I do this?

Am I right in saying that “this” is an object, and I need to convert it to a string first?

p.s - in case your interested - the value “game0” matches an xml node & the function plays a movie clip which is populated by the node attributes.