plane and pivot

[dlam]

Can someone explain the basic difference between the various shoulder planes. The turned shoulder plane, turning shoulder plane, square shoulder plane and rotated shoulder plane.
I find the application can be confusing.

For me this plane would be the basis for pivot controlled hands.

Where as a hand planer,or elbow planer would more likely have a hands or (elbow?) controlled pivot. I tend to naturally use the hands or elbow to initiate the takeaway but been shifting to a shoulder type plane during the backswing. Been experimenting using a shoulder plane when addressing the ball but not as consistent with this method.

Even looking at 10-6-B turned shoulder plane. Which I guess is the most common shoulder plane. Seems to point a line to the right shoulder. But this application would work only if the shoulder start off square to begin with and
the depends on relative position of the left shoulder.
The shoulder is a complex joint. Homer seems vague in the exact postion of the line to the right shoulder. Is it the right armpit? Is it the top of the shoulder?
For clubshaft controlled I would have thought this shoulder line could be more precise.