by the way, I really don't understand this 'being as specific as possible' philosophy....if you type A means A major, i.e. A,C sharp and E, nothing more and nothing less. A7 means the above triad plus a minor seventh from the root. Nothing more should be specified.

But if I am in the key of A major, and I type E7, and BB plays back E7b9, and I don't want that because at the same time a passing note F sharp is playing in the melody that I recorded, then it's certainly not my fault that F and F sharp are clashing.

E7b9 in that key would be a so-called 'borrowed chord'. BB should even have menus for that, or else just play back E7. If the user wants a b9 top, he can play it in the melody notes, if not, it's ok too.

I think is really all much simpler. All that is needed is to program the styles and RT with the least amount possible of passing tones, alterations and extensions. Keep it simple, don't overcrowd the passages. If I want a Lydian fourth on a maj7 chord, I'll play it in the melody, or not. Why complicating things ? The computer already takes a valuable amount of time from our lives. Simpler is better!