RNS:: Clié Jog MP3 Playback Hack (CJMP Hack) overrides default Jog Dial navigator's functionality with its own: Push the Jog to toggle the playback. Push-and-hold the Jog for the next track. Rotate the Jog to adjust the volume level. ...any time, anywhere! You can however toggle between the default and the CJMP Hack functionality at any time by the press-and-hold of the Back button.