[drewitgolf]

Thanks for explanation. Now I understand the "out" part. But it leads me to one more question: why is the on-plane swing not "cross-line" at the impact point?

Thanks,
DK

The Thrust or Action can be cross-line, but the motion is on-line.

As long as the ball is hit before low point, it is considered an In-Side Out Impact, but not an Inside Out Stroke unless the Plane Line and Line of Flight are not one in the same.