A cogged positioning system uses the concept of a detent - a pin, ball, pawl or bump that fits against a mating cavity. Usually there is some kind of spring to allow the detent to disengage when enough force is applied. This gives the familiar click as a knob is rotated.
So to answer the question the interface is called a detent. Google search detent ball for examples of how a detent works.
Wiki definition here https://en.wikipedia.org/wiki/Detent