...Incra has positive settings at common angles...
Instead of notches, JessEm uses a pin. I've tweaked the contrast on the closeup photo to make this easier to see.
A = spring loaded angle pin, pull to unlock then rotate 90° to lock in the extracted position for free-rotation of main assembly
B = holes for the angle pin to seat
C = scale diamonds indicate lock angles @ 0,15,30,45°
It's too graphically crowded for a diamond at 22.5° but as you can see there is an index point.
