ΤΖ250Τ '87, YPVS Curve

I repaired a TZ250 YPVS controller today that belongs to Dale(UK). It's from a 1987 TZ250T model and I came across another one unknown YPVS setting that I'm sharing below. This setting doesn't seem to do a lot and it's more like an "on-off" switch for the exhaust valves, as it starts opening the valves at 7.500rpm and it completes movement at about 8.000rpm.

And here are a few photos from Dale's bike.

Cheers.