SoOffscreenRenderer(3) on Linux
The text a777d87362b9, as Debian 7 (Wheezy) shipped it.
The SoOffscreenRenderer class is used for rendering scenes in offscreen buffers. If you want to render to a memory buffer instead of an on-screen OpenGL context, use this class. Rendering to a memory buffer can be used to generate texture maps on-the-fly, or for saving snapshots of the scene to disk files (as pixel bitmaps or as Postscript files for sending to a Postscript-capable printer).