MEDIA_ID_PREFIX entry in vm.conf
If this entry is specified in vm.conf, it defines the media ID prefixes to use for media without bar codes. This entry is read and interpreted on the host where vmcheckxxx and vmupdate are running as part of the robot inventory operation.
MEDIA_ID_PREFIX = media_id_prefix
The best way to add media to a robot is to use the Robot Inventory Update Volume Configuration operation.