Nit Picky Atemi
Some time ago, I classified the different kinds of atemi used in our dojo.
One of them I described as a middle-knuckle punch done with the elbow down and the fist inverted.
I'll have to correct myself.
That kind of atemi is done with some degree of angle _between_ inverted (call it 180 degrees) and vertical (90 degrees).
If you'll try it, you notice that having it 180 degrees puts something of a strain on the forearm and elbow when punching with power. So, don't do that.