For a velocity mode servo:
P = Proportional term
I = Integral term
D = Derivative term
FF0 = Command feed forward
FF1 = Velocity feed forward
FF2 = Acceleration feed forward
In a control loop for velocity mode servos, typically
only P,FF1, and perhaps FF2 are used
gnipsel.com/linuxcnc/tuning/servo.html
Is a basic velocity mode drive tuning tutorial