typedef int PK_FACE_trim_surf_t;


This data type is used to select what surface is to be used by
PK_FACE_output_surf_trimmed.  It has two values:

    PK_FACE_trim_surf_own_c            use copy of face's own surface
    PK_FACE_trim_surf_bsurf_c          use B-spline approximation of face's
                                       surf