It's a file in addition to OS3 that enables the keyboard to better handle sophisticated chords with the audio guitars.
I loaded the file right before my job tonight but didn't get a chance to pay much attention to what it did. I had a guitar player with me and I would have had trouble determining what he was playing and what the styles were doing.
I'll test it tomorrow night.
BTW, the guitar player was blown away with the sound of the Audya, as is everyone who has heard it.
I'll try to post some recordings soon.
DonM