== Improve symmetry of transformation equations == 

 I would like to see the diagram modified slightly in order to make the equations simpler and more elegant in my view. A non-exhaustive perusal of talk entries indicagtes that this topic is not covered. I would have liked to demonstrate the changes, but I could not figure out how to edit mathematical Wikipedia expressions. 

 I refer to the left hand (delta) portion of the article's main diagram. Using my representation for subscripted symbols, I would replace Rc, Ra, and Rb by Ra, Rb, and Rc respectively. Doing so will associate the first three letters of the alphabet, abc, with the first three natural numbers, 123 in order. This will correspond to node order numbers. That will remove one source of confusion when trying to follow the details. There will be more symmetry to the transformation equations.