As I was training this morning, it occurred to me that someone figured this stuff out and then the forms came later. The structure was applied to whatever the internal arts are after they were completely understood.
So, for example, you realize that the vascular system was mastered before the interstitial fluid. You design a form (the Fire Palm Change) that specifically emphasizes the vascular system and then you design a form that deals specifically with the interstitial fluid (the Water Palm Change). The trick is you know that the Fire Palm Change will begin developing the next step providing it, the Fire Palm, is performed and mastered correctly.
The process would have been fully understood first. Then the forms followed.