struct PK_BODY_loft_planar_clamp_s
    {
    PK_VECTOR1_t    normal;
    double          magnitude;
    };

typedef struct PK_BODY_loft_planar_clamp_s PK_BODY_loft_planar_clamp_t;



This structure holds the normal vector of plane and magnitude of derivatives
relative to a default value.


The planar clamp structure has the following fields :

normal         The normal vector of the plane for clamping the loft. All
                 cross-boundary tangents of the loft at the clamped profile or
                 guide are hence perpendicular to this normal vector.
                 Negating the normal will have the effect of reversing all
                 cross-boundary tangents.

magnitude      A scalar representing the magnitude of the loft derivative
                 at the clamped profile or guide relative to a default value.
                 If magnitude is set to zero, the default value will be used
                 automatically.

                 When clamping profiles, and there is a guide wire specified
                 for the loft, the loft derivative along that guide wire is
                 completely determined. The magnitude field must then be set
                 to either unity or zero to ensure the use of the default value
                 there.

                 When clamping guide wires, the magnitude field must always
                 be set to either unity or zero, since there will always be
                 profiles where the loft derivative is completely determined.