This code list is used to indicate which sort of curve may be approximated by a particular B-spline. The potential values are:<br/> -- polylineform: a connected sequence of line segments represented by a 1 degree B-spline (a line string).<br/> -- circularArc: an arc of a circle or a complete circle.<br/> -- ellipticArc: an arc of an ellipse or a complete ellipse.<br/> -- parabolicArc: an arc of a finite length of a parabola.<br/> -- hyperbolicArc: an arc of a finite length of one branch of a hyperbola.<br/>