(= (Orientation (Reference-Frame Planar-Mace)
(Reference-Frame Ground))
(Simple-Rotation 3 (Alpha Planar-Mace)))
(<- (X ?X)
(Dot (Position (Reference-Point ?X) (Reference-Point Ground))
(Basis.Vec (Reference-Frame Ground) 1)))
(<- (Y ?X)
(Dot (Position (Reference-Point ?X) (Reference-Point Ground))
(Basis.Vec (Reference-Frame Ground) 2)))