A Barcode is assigned to a Volume (tape, box, etc) to give it a unique identity and make it identifiable from all other Volumes.
At a minimum the Barcode must be unique to the Customers Media Type. TapeTrack does not allow duplicate Volume-ID's (Barcodes) within each Media Type but can also be set to disallow duplicate Volume-ID's within a Customer-ID or globally.
If you have multiple Clients that exist within your TapeTrack database, setting TapeTrack to disallow duplicate Volume-ID's globally may not be able to be enforced as each Client may use a standard labelling, eg 123456L5, and have many Volume-ID's that match other Clients.
If you only have inhouse Volumes, enforcing unique Volume-ID's over your entire tape stock is an easier concept to enforce.
TapeTrack does not enforce what type of Barcodes you can use on your tape stock. As long as you have a Barcode reader that can read the Barcodes and transmit that data to TapeTrack you can utilise any available Barcode format.