Standard_EXPORT virtual Standard_Boolean D2 (const Standard_Real Param, TColgp_Array1OfPnt& Poles, TColgp_Array1OfVec& DPoles, TColgp_Array1OfVec& D2Poles, TColStd_Array1OfReal& Weigths, TColStd_Array1OfReal& DWeigths, TColStd_Array1OfReal& D2Weigths) Standard_OVERRIDE;
//! give if possible an bspline Surface, like iso-v are the
Standard_EXPORT virtual Standard_Boolean D2 (const Standard_Real Param, TColgp_Array1OfPnt& Poles, TColgp_Array1OfVec& DPoles, TColgp_Array1OfVec& D2Poles, TColStd_Array1OfReal& Weigths, TColStd_Array1OfReal& DWeigths, TColStd_Array1OfReal& D2Weigths) Standard_OVERRIDE;
//! give if possible an bspline Surface, like iso-v are the