It's used to change around the default MIDI scale, so that you can play with early scales or even scales from other cultures. It's really cool if you get it working with your keyboard. Unfortunately, there's not a lot of software that supports it, although I think Logic Pro did at some point.
Hey err, well I may have stumbled upon this before I knew of its importance, but I could also be full of myself :P Regardless, thank you for bringing it!!
It's used to change around the default MIDI scale, so that you can play with early scales or even scales from other cultures. It's really cool if you get it working with your keyboard. Unfortunately, there's not a lot of software that supports it, although I think Logic Pro did at some point.