A MIDI messages which tells the synth to come out of a "poly" mode, as defined in the MIDI channel modes concept. The synth will, depending on whether Omni mode is on or off, go into mode 2 (in which it will receive messages on any channel and play monophonically), or Mode 4, in which the synth may allocate individual voices to different channels. In practice, this is seldom implemented as written above; there is almost no use for mode 2 today, and few synths implement mode 4 as written in the specification. When going into mode 4, the message has a parameter that can in theory tell the polyphonic synth how many voices it should allocate across channes, but on the few synths that implement mode 4 at all, this parameter i usually fixed by the number of voices in the synth, or the maximum nu