If the robot supports bar codes and the volume has readable bar codes, a prefix is not required because NetBackup creates media IDs automatically.
You can either select from a list or enter a prefix.
The list contains the following selections:
To specify a prefix that is not in the list, enter the new prefix in the list box. NetBackup uses the prefix only for the current operation.
You can specify a prefix of one to five alphanumeric characters. NetBackup assigns the remaining numeric characters to create six characters. For example, if the prefix is NETB, the media IDs are: NETB00, NETB01, and so on.
Information about the vm.conf file is available.
See the NetBackup Administrator's Guide for Windows, Volume II..