Cartridge File Protection
Each tape cartridge includes a file-protect selector 3(see Figure 16) that, when
set to the file-protect position, prevents writing on or erasing data from the tape.
Normally, cartridges used in the 3494 should not be manually file-protected. If
required, software can be used to file-protect the cartridges. This allows the host,
when appropriate, to identify a cartridge that no longer contains current data and
can be a scratch cartridge. Do not file-protect scratch cartridges because new data
cannot be written to file-protected cartridges. For additional information, refer to

Care and Handling of the IBM Magnetic TapeCartridge

Cartridge System Tape Labels
Each tape cartridge in the 3494 must have external labels that are operator- and
machine-readable. The labels identify the volume serial number (volser) and type of
cartridge. Currently supported labels are Tri-Code, available from Wright Line
Corporation, Tri-Optic, available from Engineered Data Products, and labels from
Information Data Storage.
Note: The only exception for the label requirement is when using the Unlabeled
TapeOperations function. See “Unlabeled Tape Facility” on page 22 for more
information.
The volser label contains up to six characters, and the separate media-type label
provides a seventh character for media-type identification. Avolser can contain one
to six characters, with blanks padded on the right for a volser with fewer than six
characters. Characters can be uppercase A–Z and numerics 0–9. Each tape
cartridge typically has a separate single-character media-type label that identifies
the cartridge type. The media-type label character for a Cartridge System Tapeis 1,
for an Enhanced Capacity Cartridge System Tapeis E, and for High Performance
Cartridge Tapeis J.
Note: See “Cartridge Tape”on page 18 for the process used to determine the
cartridge media type.
Figure 16. Cartridge System Tape
20 Magstar 3494 TapeLibrary Operator Guide