CC#2 is officially Breath Control, but for those with a joystick controller, as opposed to separate pitchbend and modulation wheels, it’s typical to see +y moves (pushing the joystick up) generate CC#1 and -y moves (pushing the joystick down) generate CC#2. It’s kinda like having a 2nd mod wheel.
I’ve forgotten the last time I used a breath controller… I suspect it was around 1992 using a Yamaha KX-5 and BC1 on stage. They were the days…