A TrackerInput represents a link to a particular part of a device, and can read data from it and feed it to a Meta_TrackerPRSLink.
These nodes are automatically created, either by the current Desktop Immersion mode, or by a tracker xml configuration loaded at startup (Immersive license feature required for tracker xml support).
string - Name of driver providing this value, for information only.
string - Name of the instance; which part of the device is this data from. Examples may include joy-pos for a joystick axis, or eye-pos for an eye position.