Being 'firmware' rather than computer software, there weren't ever any officially published release notes for ML software version V1.40.
The main functional difference is the extra MIDI functionality from the input PAFL switches, but there was also a bug fix for glitching VCA levels.
Something like this, adapted from the manual is appropriate:
MIDI AFL Messages SysEx message strings are transmitted each time an output channel AFL or input PAFL switch is selected or released.
These are for use with BSS and dbx speaker management systems to automatically select the remote control surface associated with the input or output being P/AFL monitored.
F0 00 20 18 7F 20 cc F7
dbx Drive Rack
F0 00 01 1E 7F 7F 20 cc F7
Where cc = the same hex value as the associated channel mute in the MIDI implementation chart.
These messages are subject to further development and addition.