The SweepOneRail type exposes the following members.
If the input rail is closed, ClosedSweep determines if the swept breps will also be closed.
If true, the sweep is linearly blended from one end to the other, creating sweeps that taper from one cross-section curve to the other. If false, the sweep stays constant at the ends and changes more rapidly in the middle.
0: don't miter, 1: intersect surfaces and trim sweeps, 2: rotate shapes at kinks and don't trim.