If VMD is compiled with the VRPN option, it will look for files that specify how to access the external spatial tracking devices. These files are read whenever VMD is told to initialize a specific external device. The Tracker library will load the first file it finds in the following search order:
This last file (INSTALLLIBDIR/.vmdsensors) contains extensive comments on how to configure the sensor description files properly. If the VRPN option is omitted when compiling VMD, this file is not used.