I have updated the graphic tool. The ‘maximum angle between arms’- curve is definitely a circular arc. The tool now has a movable sled with belts, that shows the 4 angles.
From What is the max and min angles between the arms? - #47 by arjenschoneveld I found which angle is meant by the minimum 130 degrees, but I don’t see where or how this is a limitation for the area that already has been limited by the maximum angle curve. Is there data for a specific situation?