A MIDI Controller message that, when received, instructs the receiver to release all notes that are currently being sounded.It is commonly used to get rid of stuck notes resulting from missed MIDI messages or software problems. Note that it does not mean that the receiver will go silent immediately! It is the equivalent of sending a note off message for all notes which are currently sustaining; if the current patch is programmed with a long envelope release time, the notes may continue to sound for some time. Many sequencer devices and software programs, and some MIDI interfaces, have a panic button that, when pressed, sends the all notes off message to all connected devices.