...the MIDI and MusicXML that BiaB generates from notation is not "accurate", in that what is generated does not reflect the notation.
Band in a Box does not generate any Music XML at this point in time.
To the best of my knowledge, Band in a Box does not create nor send Note Off data, either. Hence the commonly found stuck synth on strings and other pads when someone hits Stop before the Duration value has ended.
We send the file to the Sinsy site and that is where the Music XML generation actually comes from.
And I'm thinking that whoever coded the Sinsy site likely used the easily obtainable Standard MIDI File Reference, which still has that almost entirely unused Note Off designation listed from when it was first written.
I haven't seen a MIDI file with Note Off data in it that was written since sometime around the mid 80s...
--Mac