ENFAPR ( face, rectan, urange, vrange, ifail )
==============================================

  Enquire whether a face is parametrically rectangular

Receives:
  KI_tag_face              *face           --- face

Returns:
  KI_cod_logical           *rectan         --- parametrically rectangular flag
  KI_dbl                    urange[2]      --- Parameter range in u
  KI_dbl                    vrange[2]      --- Parameter range in v
  KI_cod_error             *ifail          --- failure code

Specific errors:
  KI_no_geometry            entity does not have geometry attached
  KI_wrong_entity           entity is not a face

Description:

      Determines whether a face is parametrically rectangular.

      If 'rectan' is returned as KI_true then 'urange' and 'vrange' will
      contain the parameter limits of the rectangular area of the surface in
      which the face is defined.

      For each pair of parameter limits, the following rules apply:

        (i)   The first element will always be less than the second.

        (ii)  Both elements will lie inside the parameter range, as given by
              ENSUPA, unless the corresponding parameter is periodic.
              In that case the first will lie in the range, and the difference
              between the two will not exceed the period.

      If 'rectan' is returned as KI_false then all the elements of 'urange'
      and 'vrange' will be 0.0.

      ENFAPR does not guarantee to detect that a face is parametrically
      rectangular but it will never claim a face is parametrically rectangular
      when it is not.