Quote:

This recalcitrant Jazquint style defeats a lot of velocity=0 commands, though ...



So I have looked at the exported MIDI file with a special editor to inspect the raw data. It turns out that on the guitar track on each beat the complete chord is generated *multiple* times with an offset of some ticks, and for each of these chords all but one Note On are immediately followed by a Note Off (velocity=0). Thus a strum effect is created but the method seems questionable. I'd suspect that sending Note On and Note Off with same pitch on the same tick may confuse some synths.