The ?-spline provides bias and tension control facilities for creating geometrically continuous curves and surfaces. Although geometric continuity is a more appropriate geometric measurement of smoothness than parametric continuity, parametric continuity is still necessary in some applications. This paper proposes a new C2 continuous spline scheme called the a-spline which provides weights and tension control. The new scheme is based on blending a sequence of singular reparametrized line segments with a piecewise NURBS curve. The idea is extended to produce a-spline surfaces.