An "nth degree" polynomial spline shall be defined piecewise as an n-degree polynomial, with up to Cn-1 continuity at the control points where the defining polynomial changes. This level of continuity is controlled by the attribute numDerivativesInterior. Parameters shall include directions for as many as degree - 2 derivatives of the polynomial at the start and end point of the segment. GM_Linestring is equivalent to a 1st degree polynomial spline. It has simple continuity at the controlPoints (C0), but does not require derivative information (degree - 2 = -1). <br/>NOTE The major difference between the polynomial splines and the b-splines (basis splines) is that polynomial splines pass through their control points, making the control point and sample point array identical.<br/>