[EdZ]

Setting aside the "feels", I'm just trying to understand the definitions. I believe the confusion is that I'm using the terms "square" and "opening" in relation to the inclined plane. But it seems that the alignment of the clubface for angled and vertical hinging is termed relative to the target line or baseline. Yes?
So angled hinging sees the clubface close to the plane line, but stay sqaure to the inclined plane, Yes?

And shouldn't "closing only" demonstrate with no swing of the shaft? As soon as the clubhead passes low point, it IS "laying back", no?

Part of the reason you are confused is that you are focused on hinge being on the plane, and not the left shoulder.

This is a central point of confusion for many when learning about hinge motion.

the hinge is in the left shoulder

If you have the book, look at 1-L

Now picture that as your left shoulder and arm

so while you are correct that with an angled hinge, the clubface does stay perpendicular, or vertical, to the angled plane, or in your words 'square', that isn't the whole picture and is why you are confused about the horizontal example


forget plane/target lines for a moment, and just imagine the 3 basic planes - horizontal (a door), angled (a roof) and vertical (a dog door)


imagine there is a door with the hinge at your left shoulder

the clubface stays 'in' the door - which is easy to see if you lift the club up to shoulder high, but as soon as you lower it down, the confusion sets it

you are still keeping the clubface 'in' the door, but on the tilted plane, and to do that, you have to let the left wrist turn going back, and roll going through

by staying 'in' the door, the clubface is appearing to open and close to the target, but it is staying 'square' - 'in' the door that is mounted at the left shoulder

next, you'll see how the right arm is what 'slams' the door, by straightening - and that motion is either an active straight line push (hitter), or the throw out (swinger) of the club caused by the pivot