I try to illustrate by drawings what have been covered in some previous posts, namely, How to Focus? Converging for Control Zone – Amoeba Membrane Analogy, What is Elbow Power? – Solid and Immense to Opponent, Light to You, and Multi-directional Forces in the Arm – Pinning Elbow Tip in Space. Two movements in the second part of Siu Nim Tau were chosen for this purpose. They are: Cutting Downward and Cutting to Both Sides. To perform any of the movements, the mind sets up the power base by linking up as many joints as possible inside the body up to the elbow tips, which is then reflected as the solid and immense elbow power.
At the same time the elbow tip, being pinned in space, separates the power base and the forearm (plus palm structure) as two distinct entities that can operate independently.
The elbow pins (both sides) are projected to the front (even beyond the opponent’s location) in order to converge towards your centreline out at the Projected There, not staying at the Physical Here. As such, the cutting movement, whether downward or to the sides, is done by navigating the two elbow pins accordingly at the Projected There, while the converging intent is still fully present. Note that multi-directional forces are then in play.
For detailed explanation, please refer to the three posts.
A postscript: Projecting out there (the “virtual” control zone) is not something ultimate, but a pathway. When you are able to directly operate points from inside, there will only have the physical control zone; no need to go “virtual”.