ActionScript for Flash MX: The Definitive Guide, 2nd Edition By Colin Moock
Chapter 18. ActionScript Language Reference
prevFrame( ) Global Function
Flash 2
send a movie's playhead back one frame and stop it there
prevFrame()
Description
The prevFrame( ) function moves the playhead of the current timeline back one frame and stops it there. The current timeline is the timeline of the main movie or movie clip from which the prevFrame( ) function was invoked. The prevFrame( ) function is synonymous with gotoAndStop(_currentFrame - 1). If it is invoked on the first frame of a timeline, prevFrame( ) simply stops the playhead on that frame, unless another scene precedes the current scene, in which case prevFrame( ) moves the playhead to the last frame of the previous scene.