Dynamic or volume of notes (also known as MIDI velocity) is represented as in the MIDI specification using integers from 0 (silent) to 127 (loudest). That’s a total of 128 volume settings. The music library defines the following dynamic constants:

FFF = 120
FORTISSIMO, FF = 100
FORTE, F = 85
MEZZO_FORTE, MF = 70
MEZZO_PIANO, MP = 60
P = 50
PIANISSIMO, PP = 25
PPP = 10
SILENT = 0