SoSwitch(3) on Linux
The text e20dd60c038d, as Debian 7 (Wheezy) shipped it.
The SoSwitch class is a group node which selects one child subgraph for traversal. Which child to traverse is controlled by the application programmer by using the SoSwitch::whichChild field. In addition to picking out a single child for traversal, it is also possible to flip all children on or off for traversal.