If that's true, John, then effectively you are saying that the only legal User Tracks (that could be shared with others) would only be recordings of acoustic instruments, but nothing at all from from the digital realm, because you would be using sounds created by someone else. That would mean, for example, that I could record myself playing on an acoustic piano and capture it for a User Track, but not on my Kurzweil Digital Piano, and then especially not from my Casio keyboard controller using a softsynth, even though what I am playing is all mine (and would be the same thing on all three scenarios, with variations in the resulting sound). I could then not share my creation with others to be able to create music "in the style of me" (not that anyone would really ever want to do that).
