Regions with CabcdCabcd > 0 are shaded, the boundaries being the roots to CabcdCabcd = 0. The shaded region extends to indefinitely to the right where CabcdCabcd approaches 0 as x goes to infinity.The diagram holds for all Kerr balck holes in Boyler-Lindquist coordinates (x=r/a, a is not zero). An alternate view in the Kerr-Schild plane.