CRCPCU ( surf, uorv, param, curve, ifail )
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  Creates a constant parameter line curve on the surface.

Receives:
  KI_tag_surface           *surf           ---  Underlying surface.
  KI_cod_papr              *uorv           ---  Constant parameter.
  KI_dbl                   *param          ---  Constant parameter value.

Returns:
  KI_tag_curve             *curve          ---  Constant parameter line curve.
  KI_cod_error             *ifail          ---  failure indicator.

Specific errors:
  KI_wrong_entity           Unsupported surface type
  KI_not_on_surface         Parameter out of range
  KI_at_singularity         Curve not possible at parametric singularity
  KI_invalid_geometry       Curve not possible
  KI_bad_parametric_prop    inappropriate property

Description:

  This function creates a curve corresponding to a constant parameter line on
  the surface.

  The type of the curve returned is simplified wherever possible.  However,
  when the supplied surface is a foreign geometry surface (type TYSUFG)
  then the type of the resulting extracted curve will be TYCUCP and when it is
  an offset surface (type TYSUOF) then the resulting extracted curve may be of
  type TYCUSP.

  In some cases the returned constant parameter curve may extend beyond the
  confines of the surface. This case is most likely where the returned curve is
  simplified to a curve which contains the constant parameter curve as a subset.
  An example of this would be a line of constant u parameter on an lemon torus.
  This constant parameter curve would be returned as a complete circle.

  'surf'  is the existing surface from which the curve is extracted.

  'uorv'  defines whether the curve is :
                  Constant u ( uorv = PAPRUP ),
                  Constant v ( uorv = PAPRVP ).

  'param' supplies that constant parameter value. If ENSUPA indicates that
          'surf' is not periodic or infinite in the parameter 'uorv', the
          value of 'param' must lie within the range specified by ENSUPA for
          'surf'.

  'curve' is the returned tag of the curve, if the operation succeeds.

  It is not possible to extract constant v parameter curves (PAPRVP) from
  blend surfaces (type TYSUBL).

  If 'surf' is not an orphan, then the constant parameter curve will be created
  as construction geometry in the owning part of 'surf'.