 Since "h" is a non-degenerate two-form it follows that "Z = 0".Notice that since "M" has a non-degenerate second fundamental form it follows that "h" is a non-degenerate two-form.Since "Z = 0" the set of ambient points "x" for which the restricted function formula_27 has a singularity at some "p" is the affine normal line to "M" at "p".