The description in the manual for the range Parameter for the Vol-Pedal is correct but not so easy to understand.
I made mistake after upgrade to Vers.4.0 because my setting was set to default and did not remember as it was before.
The signalisation of a bipolar function with a unipolar bar display in the Rig setting screen is confusing.
I would propose to modify the indication to a bipolar bar display according the function of the Vol-pedal which shows the relation (plus or minus) to the normal Rig-volume (Pos 0 at the bar) depending on the pedal position.
I made a short example to show what I mean (but I am not a computer graphic artist )