G95 is "Feedrate in Inches per Revolution".
In g95 mode the tooling plate will not move if the spindle is not turning.
The "f" value is how far the tooling plate will move per revolution of the spindle (ipr). The limit is determined by spindle speed: speed (rpm) times distance (ipr) must be less than 300. For example, at 100rpm, you can cut a thread with a three inch lead (g95f3). At 4000rpm the maximum value for "f" is 0.075 (g95f0.075)
G95 is used for almost all cutting and threading. The movement of the tooling plate is synchronized to the spindle rotation.