[Daryl]

...as the pressure of pp4 works against the onplane pressure of pp3, this tilts the spine and drops the right shoulder axis tilt until pp3 can trace down the plane line.

Also the pressure of pp3 towards the plane line is what keeps the level condition of the right wrist....

Mathew,
By "work against the onplane pressure of pp3", do you mean it exerts force against lag? Just trying to clear the fog. I understand and am clear on the rest. Good post.