I concur with Robert. Belt would make a noticeable noise over the teeth. I believe it works something like this:
Lever at grip; is where you let the lever out and the bike takes off... as soon as it leaves the grip. It says it has a thick set of frictions that are pushing the springs with a lot of tension so as not to slip.
Lever near perch; is where it takes a distance from the grip before it engages. The closer to the perch, the thinner the frictions, the weaker is the tension of the springs moving closer to static tension, rather than compressed. Slip occurs.
Lever at perch; is where the gap is not present. There is no inner cable freeplay so a clutch adjustment would be needed.
A visual at different style pressure plates:
Flat plate; is where you can see the pressure plate move into the big clutch outer' fork arms. The friction plate tangs slide into these slots. The deeper the entry, the more the springs grow and tension is lost to clutch slippage.
Wave plate; is where this plate is like a large coffee cup plate that is concave in shape when static. It acts as one big spring if it is pushed flat. The flatter the wave plate, the fatter the frictions. The wave plate starts to concave, it loses tension and then the clutch slips.