ohhhh you mean this? I think it's for fine adjusting the lever feel, and maybe allowing the lever to pull cantis as well as Vs - closer to the pivot is canti (pull ratio changes as you pull), further from the pivot is vee (pull ratio is basically linear). same mechanical principle as the pauls levers with choice of two pivot points.
If it's like the Sora ones, there is a little screw on the reverse side; you unscrew it, take the stopper piece out, slide the pivot point up (or down), then replace the stopper piece.
ohhhh you mean this? I think it's for fine adjusting the lever feel, and maybe allowing the lever to pull cantis as well as Vs - closer to the pivot is canti (pull ratio changes as you pull), further from the pivot is vee (pull ratio is basically linear). same mechanical principle as the pauls levers with choice of two pivot points.