Loading external variables into Flash opens up a whole world of possibility.
In the past, _root was used to access variables passed via the FlashVars attribute. In ActionScript 3, the code you use is much more official; in fact, there is even a new class named LoaderInfo. You can use gthe LoaderInfo class to access these external variables within Flash. The first thing that needs to happen is the passing of the external variables via the FlashVars tag into Flash.