SoVRMLVisibilitySensor(3) on Linux
The text 9853ba4c4f25, as Debian 6.0 (Squeeze) shipped it.
The SoVRMLVisibilitySensor class will generate events based on visibility. The detailed class documentation is taken verbatim from the VRML97 standard (ISO/IEC 14772-1:1997). It is copyright The Web3D Consortium, and is used by permission of the Consortium:.