A related question is the total frames of a layer? For example, I'd like to find out the total frames (or the beginning and ending frame numbers) in layer audio 1, audio 2, etc without manually calculating each one. It would be a lot of work calculating each and then recalulating again when frames are changed.
Thanks again for the help,
I actually had the same question. I've worked out a way of doing it in AS3.
So first you can get all the frame labels on the MovieClip in question by using the currentLabels property (http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/flash/display/MovieClip.html). Then going through the array you can find your label as a FrameLabel object which has a frame property that will tell you the frame number (http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/flash/display/FrameLabel.html).
Hope that helps