SoNode(3) on Linux
The text bd205a579302, as Debian 8 (Jessie) shipped it.
The SoNode class is the base class for nodes used in scene graphs. Coin is a retained mode 3D visualization library (built on top of the immediate mode OpenGL library). 'Retained mode' means that instead of passing commands to draw graphics primitives directly to the renderer, you build up data structures which are rendered by the library on demand.