Test whether a shape is above or below a plane.

Input parameters:

1. Sh → Shape for plane relation test.
2. Pl → Reference plane.

Output parameters:

1. Rb → Boolean relation between shape and plane: true = above or coincident false = below
2. Ri → Integer relation between shape and plane: 1 = above 0 = coincident -1 = below
   • -1 → Below
   •  0 → Coincident
   •  1 → Above