Homer assumed Separation to be at Low Point but what if it isnt?

[nevercrosses]

So whats the difference between an inside out impact for a straight line plane line and an inside out stroke?

Is it just a matter of degree?

Does Trackman or D plane measure what we'd call Hinge Action? A rate of clubface closing or whatever?

You can call it whatever you like. If the clubhead direction while the ball is in contact with the face is pointing right of(whether it is down and to the right or to the right or up and to the right) the direction the face is pointing at separation (assuming a centered strike) the ball draws or hooks or whatever words best desrcibe it. It will have a spin axis tilted to the left (assuming a right hander) and direction of lift perpendicular to that axis.

Trackman and D Plane do not measure hinge action as it is irrelevant. The balls comes off the face at some time no matter which hinge action is employed.