B-spline Curves
A B-spline curve is more complex mathematically than a point curve. A B-spline curve's shape is determined by the number and location of its poles, which are represented as vertices of the curve's control polygon and its order.

B-spline curves are drawn with the tool in the Create Curves toolbox as well as several special-purpose 2D B-spline tools.

You can place a B-spline curve by entering data points or construct it by identifying a line string or shape.