SoIndexedNurbsCurve(3) on Linux
The text 8e1d6aee3f9a, as Debian 8 (Jessie) shipped it.
The SoIndexedNurbsCurve class is a node for representing smooth curves. Explaining NURBS is beyond the scope of this documentation. If you are unfamiliar with the principles of representing smooth curves and surfaces when doing 3D visualization, we recommend finding a good book on the subject.