[Yoda]

One last question: Does "between the shoulders" mean only the upper (cervical) spine or does it refer to the entire spine running longitudinally between the shoulders.

Per The Glossary, the alternative Pivot Center is the "Point-Between-the-Shoulders."

Interesting, isn't it, that this is the kind of question that invariably arises when a shortcut -- my deliberate elimination of the word "point" in my post -- has been taken. This speaks volumes for the necessity of a unified terminology with which to discuss the complex mechanism of the Golf Stroke.

And with no shortcuts...

No matter how much a particular issue has been discussed.