Specifies how the axis's visual range should behave when the PolarChart data is updated.
The following modes are available:
The applied mode changes depending on the visual range's position on the axis:
- at the start or middle, then "keep";
- if set to view the whole range, then "reset" (the visual range remains equal to the whole range).
The visual range does not change.
The visual range becomes equal to the whole range.