[tongzilla]

To of the three Single Wrist Action Variations -- Horizontal (10-18-C-#1) and Angled (10-18-C-#2) -- arrive at the Top On Plane.

In contrast, Single Vertical (10-18-C-#3), arrives at the Top -- typically on the Turning Shoulder Plane (10-6-D) -- with the Hands "under the Club." Here, the Left Wrist simply remains perpendicular (to the Horizontal Plane) throughout the Backstroke. In other words...

"Straight back, Straight through. Keep the clubface square (no turn or roll)."

Thus, for Pivot Strokes, Standard Action, Single/Horizontal Action and Single/Angled Action all arrive On Plane at the Top with the Clubface aligned parallel to the Inclined Plane, i.e., at approximately 50 degrees to the ground. With Single/Vertical Action, the Left Wrist remains perpendicular (90 degrees) to the ground - an Off Plane Loading motion -- and the Clubface is aligned likewise, i.e., 'Toe down'. During the Stroke, the player simply lifts and lowers his Arms as the Body Turn supplies the On Plane motion to the Arms and Hands.

As always, Vertical Hinge Action -- either through the Ball or away from it -- is a deliberate, mechanical manipulation of the Clubface. That is, a Counter-clockwise Motion on the Backstroke and a Clockwise Motion on the Downstroke. As such, it is the natural byproduct of neither Swinging (Horizontal Hinge Action) or Hitting (Angled Hinge Action). Unless deliberately employed for a specific purpose, it is, at bottom...

Steering.

The First Snare (3-F-7-A).

So...

we have established that both 10-18-C #1 and 10-18-C #2 arrive at the Top On Plane.

The difference between 10-18-A and 10-18-C#1 at the Top is more a matter of how it got there rather than the actual alignments at the Top.

But since the motion of the wrists is different between 10-18-C #1 and 10-18-C #2, and yet they both arrive On Plane, then there must be something different in the rest of the body to make sure it's On Plane.