In case this is useful to anyone, I have traced these extra uses for some of the buttons that the ProBox does not annotate as being used. They may be useful in some DAWs, though sadly not my Studio One which only accepts midi ocntroller data.
These buttons listed send midi Note data to MidiIn4 (MCUport)1.
MACKIE D8B MIDI TRANSMIT INFORMATION
RECEIVED FROM MIDIIN4 (MCUPORT)1
SETUP SECTION
SAVE - NOTE ON A#3
SAVE AS - NOTE ON B3
NEW - NOTE ON C4
LOAD - NOTE ON C#4
AUTOMATION SECTION
BYPASS - NOTE ON E4
FADER MOTORS OFF - NOTE ON G4
CLIPBOARD SECTION
PASTE - NOTE ON C5
UNDO - NOTE ON C#5
TRANSPORT SECTION
SET TIME - NOTE ON E2
JOG & SHUTTLE - NOTE ON F6
DYNAMICS SECTION
SELECT #1 - NOTE ON G#0
SELECT #2 - NOTE ON A0
SELECT #3 - NOTE ON A#0
SELECT #4 - NOTE ON B0
HELP - NOTE ON D#2