Poly pressure events
Poly(phonic) pressure events are generated by mechanical pressure sensors beneath each individual key on some MIDI keyboards. The resulting sound modulation only affects the particular note that is pressed harder (after the initial keystrike). Only a few keyboards offer this capability.
Ch(annel): MIDI channel of an event from 1 to 16.
Num(ber): Displays the MIDI note name (C3, G4, and so on).
Val(ue): Displays the amount of pressure on the key (0 to 127).