Vertical Axis Measurement
Vertical Axis Measurement: The perpendicular measurement form the midline to the bowler’s PAP.
Mo Pinel wrote
"The vertical coordinate has nothing to do with ball motion. It's an anomaly. The longer the thumb stays in the ball, the more the vertical coordinate is up. In full rollers, in which the thumb stays in the ball the longest, the vertical coordinate is usually 2+" up"