SoGroup(3) on Linux
The text 9401a47c4b4b, as Debian 7 (Wheezy) shipped it.
The SoGroup class is a node which managed other node instances. The internal scene data structures in Coin are managed as directed graphs. The graphs are built by setting up a hierarchy through the use of group nodes (either of this type, or from subclasses like SoSeparator) which is then traversed when applying actions (like SoGLRenderAction) to it.