= 0 : Plant regardless of terrain curvature. > 0 : Plant where terrain curvature is less than or equal to value. < 0 : Plant where terrain curvature is greater than or equal to -value.
= 0 : Plant regardless of terrain slope. > 0 : Plant where terrain slope is less than or equal to value. < 0 : Plant where terrain slope is greater than or equal to -value.