[Matt]

10-10-B shows vertical (only) hinge action. So you need to imagine a pure pendulum motion (like a grandfather clock), with the clubshaft vertical (perpendicular) to the ground. You'll see that this is a difficult position to get into during a real stroke.

Stand in a golf posture, with your left arm (and fingers) hanging straight down toward the ground. Now imagine a clubshaft in-line with your arm and also hanging straight down. As you swing that back and through, watch what your palm is doing -- it's facing "up" as you swing back, and "down" after low point (outside your left shoulder).

Vertical (only) hinge action is relegated to shorter shots. As you use longer clubs and take longer strokes, you start to swing on an inclined plane instead of a vertical plane. This is where dual vertical hinging (10-10-E) comes into play. That's a subject for another post.

Does that make it any clearer?