I played a Casavant with an Austin console (this organ was the original Heinz
57 instrument) when I lived in Connecticut. There was a stop tab on the far
right that allowed me to choose which manual pistons I altered the pedal
with. Hence I could set up a registration that had swell 2 & 3 change the
pedal but swell 1, 4,5,6 change only swell pistons. When the pedal & man
combinations tab was down (it was set as any other stop tab was) it activated
both the manual divisional as well as *any* pedal stops I chose. In essence,
then, it worked like a kind of general piston. Its function was not in any
way related to what was set on pedal pistons the way that the quite common
great and pedal combinations does. I found it a handy little device,
particularly when I was registering a recital program and didn't want to
waste generals to change a few choir or great or swell  stops and the pedal
without altering the other two manuals. It has a similar use to the coupler
pistons that frequently show up on large instruments.
 
Peter Nikiforuk