SoDataSensor(3) on Linux
The text 39f954092542, as Debian 7 (Wheezy) shipped it.
The SoDataSensor class is the abstract base class for sensors monitoring changes in a scene graph. If you need to know when a particular entity (as a field or a node) changes, subclasses of SoDataSensor can be used to monitor the entity and notify you when it changes.