Elbow and Waist can only close, cannot open
- The elbow and waist (from one side of the waist to the other side) must have a connection through the waist (side wall of the waist and shoulder on the same side). In this case the functional modifier is the kua.
The elbow and waist must stay on a curved or straight line, causing this connection.- Closing means to move inward, causing the distance between the elbow and waist to shorten.
- The elbow and waist can never move away from each other (please note that the meaning of this requires further clarification later on).
Source: https://practicalmethod.com/?p=14020