01 : CRASH
02 ~ 09 : DRUMS SECTION
10 : TRAP 808 HAT
11 ~ 17 : PIANO SECTION
18 ~ 20 : SUB / WOBBLE / BASS etc.
21 ~ 24 : Important(Useful) BGMs
27 ~ 32 : Unnecessary(Useless) BGMs

mu-on obj : #WAV02 'put_this_sound_for_fun.wav'

Not Always like this.