SoTransform(3) on Linux
The text 1d828263c4fb, as Debian 7 (Wheezy) shipped it.
The SoTransform class is the 'all-purpose' transformation node type. Like SoMatrixTransform, nodes of this type gives the application programmer maximum flexibility when specifying geometry transformations in a scene graph. If you want to set and keep the various components of the transformation matrix in separate entities, this node type is preferable, though.