LoopOnSound theChannel, theMarker
This function loops back to a specified frame until the sound is finished.  This is useful for animated menus and interfaces, where you want to keep things moving on the stage eventhough you are waiting for a sound to finish.
Example:  theMarker can be: any negative number, 0, or any frame label ("myLoop").  theChannel can be 1 or 2
loopOnSound(1,-4) -- back four markers
loopOnSound(1,-1)   --previous marker
loopOnSound(1,0)   --current marker
loopOnSound(2,"myLoop") --sound in channel 2 and loop to the marker named "myLoop"