[lagster]

Wrist Turn (to the right) and Wrist Roll (to the left) are true rotations. They are Swivel Actions (10-18-A).

In contrast, the Wrist can remain Vertical -- perpendicular -- to one of the Three Basic Planes (of Motion), i.e., Horizontal, Angled or Vertical. While this action may appear to Turn and Roll, there is no independent rotation. This is a Hinge Action (10-10-C/D/E).

With a Swivel Action, the Turned Wrist must later be Rolled (unless a Cut Shot is being played). With a Hinge Action, it remains Vertical to its Associated Plane.

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OK... it sounds to me like Mr. Yoda is saying that technically any actual RADIO-ULNAR activity(supination/pronation) of the left arm, whether conscious or automatic, is actually termed SWIVEL ACTION. So with Standard Wrist Action, which usually is used with SWINGING, there is a TAKEAWAY SWIVEL(pronation), a RELEASE SWIVEL into the IMPACT CONDITION( where there is a FLAT LEFT WRIST, and very slightly OPEN CLUBFACE). With the RELEASE SWIVEL, the RADIO-ULNAR ACTIVITITY is in the opposite direction as with the TAKEAWAY SWIVEL. Finally... there is the FINISH SWIVEL, where there is additional RADIO-ULNAR ACTIVITY, and probably some left SHOULDER JOINT ROTATION, as well as PRONATION of the RIGHT FOREARM, to keep the shaft on plane at this stage.

With SINGLE WRIST ACTION, which usually is used with HITTING, but can be used with SWINGING, this is a little different. In the TAKWAWAY there is a LEFT WRIST COCK, but not a TURN. So there is no TAKEAWAY SWIVEL here. On the Downswing, "Normally" there is no RELEASE SWIVEL with SINGLE WRIST ACTION. The "Clubhead Fix alignment remains undisturbed." Some Hitters use the Finish Swivel, and some do not.

Now... Hinge Action is a different thing.