Hi Steve B.,
"An in the footwork looks very similar to Ji."
I think much of this is going to have to do with how the terms are defined. For example, "An" can be translated as "press down" and "Ji" can be translated as "Squeeze." Translating them these ways might change the applications you describe. Anyway, imho, for this particular argument, it might be possible to think of "peng, an, lu, ji, etc" as directions. I'm not saying that this "is" what they "are" in any definitive sense, only that they can also be related to directions. Well, even easier is to think of "4 sides" and "4 corners." To these we can attach directional markers like N,NE,E,SE,S, etc. OK, this is actually an insufficient description because we are working in 3 dimensions. As in the description of "peng" as "ward off slantingly upward." Though I've never heard it described as such, "lu" in most cases is done in the opposite direction: i.e., "diagonally downward." Again, I'm not arguing anything more than that the names can correspond to directions. I'm not saying that this is traditional theory either, only that this is a way to look at it. Well, if you can accept that, then it might be possible to accept that each leg has "sides" and "corners." And that "pressing down" --while advancing-- with the knee (i.e., using the front-side) aginst the opponent's knee could be considered an "An." Of course, this is a question of position, since using the front of the knee directly against the other's front knee could be considered a violation of the principle of opposing force with force. So, front of knee against side of knee is a lot safer --and probably more effective (ymmv). Hmm, it's also probably true that these things are more clearly demonstrable in steppting push-hands or in active-step styles. Anyway, just a thought.