The desired point on the bowling ball which serves as the axis of rotation after release. The bowler's style determines this location. It is measured from the center of the grip over a distance along the midline and up a distance along the mid plane (vertical axis line).
The axis of the ball during the first few revolutions that is created totally by the bowler's release style.
Point on the surface of the ball that is the end of the bowlers axis of rotation, on the positive side of the ball.