[Yoda]

Of the plane and plane line, I believe compliance with the plane line to be more important.

The Sweetspot is always swinging on a Plane. It may not be the Plane the golfer wants it on -- unintentional Twists and Loops abound -- or, even the Plane he thinks it's on ("I feel no shifts at all." -- Jim Furyk). Nevertheless, it's always on some Plane or other. In fact, its motion defines the Plane being employed.

With the Turning Shoulder Plane (10-6-D), for example, the Loading Action is in a Vertical Plane (and not an Inclined Plane). For the most part, though, the ideal is to play 'Inclined Plane Golf'. In which case, the Club usually shifts almost vertically during the Backstroke from an Elbow Plane at Address to one of the Shoulder Planes (Turned or Squared) at the Top. This is defined as the Single Shift (10-7-B). A Double Shift (10-7-C) occurs when the Club returns to its original Plane Angle during the Downstroke.

At all times, however, with or without a Plane Shift, the ideal is to maintain "a straight line relationship to a straight line" (2-N-0). In other words, the Clubshaft -- one end or the other per 1-L-#6 -- continues to point at the Baseline of the Plane. [Note: Though the Inclined Plane concept always references the Sweetspot Plane unless otherwise noted, the Clubshaft Plane (the visible) is used as the Visual Equivalent (2-F) of the Sweetspot Plane (the invisible). In fact, they are indeed one and the same as the Clubshaft rotates about the Sweetspot during the Backstroke, Downstroke and Follow-Through, thus causing the Clubshaft and Clubface to lay on the same Plane.]

So, no matter what Plane or Planes are employed, always remember:

"Changing the Plane Angle has no effect on the Plane Line" (1-L-#18 ).