[Daryl]

I found the Quotes:

This is from the 1st Edition

6-B-4-0. THE FOURTH POWER ACCUMULATOR The angle formed by the Left Arm and the Left Shoulder forms the Fourth Power Accumu¬lator. It is not only an independent Power Accumulator, but its Triggering function as the Checkrein of the Right Elbow Power is also vastly important and it thus can be the Accumulator of the Accumulators or Master Accumulator.
As Accumulator #4 its function is to actuate the Primary Lever Assembly when using the Pull Basic Stroke, which requires a non-participating Right Arm. It is "supported by" rather than "operated through" its Pressure Point-#4. Which is any point along the Left Side contacted by the straight Left Arm.
It qualifies as #4 Accumulator only when the Shoulders are Turning and the Left Arm seeks its "in-Line" position with the Shoulders. Otherwise it actually substitutes for the Pivot to introduce the circular motion required to produce Centrifugal Force.

This is from the 7th Edition

6-B-4-0. THE FOURTH POWER ACCUMULATOR The angle formed by the Left Arm and the Left Shoulder forms the Fourth Power Accumulator. The In-line condition it seeks is with the Shoulders. It is not only an independent Power Accumulator, but its Triggering function as the Checkrein of the Right Elbow is also vastly important; it thus, can be the Accumulator of the Accumulators - or Master Accumulator. (Also see 2-M-4.)
As Accumulator #4, it is Pivot (Body) Power supplying the initial acceleration of the Downstroke to throw the Lever Assemblies toward Impact by the Thrust of the Shoulder Turn. (See 7-13.) Another major contribution to Impact Power is geometric - it is the first link in the Swing Radius power train between the Club and the Feet.
"Left Arm Power" in any form or amount can still be considered #4 Accumulator Action. Otherwise, it actually substitutes for the Pivot to introduce the circular motion required to produce Centrifugal Force.

Red by Daryl