SoQtPlaneViewer(3) on Linux
The text a2c966d43be1, as Debian 6.0 (Squeeze) shipped it.
The SoQtPlaneViewer class is for examining 3D models by moving the camera in orthogonal planes. The SoQtPlaneViewer is a viewer that is useful for 'CAD-style' applications, where you want the end-user to examine your model with the viewpoint set from one of the three principal axes.