Basically just the midi notes but still useful 
Interestingly you can apparently activate the ext source from midi (I haven’t tried yet).
NAME:SP303
OUT:A
CHANNEL:5
N35:EXT
N36:A1
N37:A2
N38:A3
N39:A4
N40:A5
N41:A6
N42:A7
N43:A8
N44:B1
N45:B2
N46:B3
N47:B4
N48:B5
N49:B6
N50:B7
N51:B8
N52:C1
N53:C2
N54:C3
N55:C4
N56:C5
N57:C6
N58:C7
N59:C8
N60:D1
N61:D2
N62:D3
N63:D4
N64:D5
N65:D6
N66:D7
N67:D8