*/
  public void map_grid2d (int un, double u1, double u2, int vn, double v1,
                          double v2) {

    RequestOutputStream o = display.out;
    synchronized (o) {
      begin_render_request (o, 149, 44);
      o.write_double (u1);
      o.write_double (u2);
      o.write_double (v1);
      o.write_double (v2);
      o.write_int32 (un);
      o.write_int32 (vn);
    }
  }