I was thinking of it as the Heaven and Earth powers, which I think are the same as fire and water?
Or am I more confused than I had anticipated?
I think we're all confused when we try to put these things in specific terms.
So I was hoping you knew what in-yo was well enough that you could tell me.
Far as I have so far puzzled out in reverse, rather noticing something in my own training and then trying to connect it back to what I've seen, it seems to refer, grossly, one side supports the other, and vice versa, for sufficiently vague definition of side. The 6-directions seem to be a form of that in a artificially linear sense along 3 different axes, while it seems to operate far more profoundly in the rotational sense with linear directions building off of it, like one side of the pelvis going one way driving the other side the other way. In writing it seems sorta quaint, but when each part of the body is doing it to each other, it imparts a really odd feeling to movement, and it seems like it fits the bill for in-yo.