DEC MicroVAX 3100 Owner's Manual page 150

F.1.1 Labeling a Tape Cartridge
Always label tape cartridges. A slot for the label is provided on the front
of the cartridge, as shown in Figure F -2. This label is visible when the
cartridge is in the drive. Labels or markings on any other part of the
cartridge can interfere with proper operation of the drive. Do not write
directly on the cartridge with pen, pencil, or other marking medium.
The labels provided with the COMPACTape or COMPACTape II tape
cartridge have spaces to check the cap'acity of the tape cartridge. If data
was written to the tape cartridge with a TK50 or a TZ30, the 95Mb block
on the label should be checked. If data was written to the tape cartridge
with a TK70, the 296Mb block on the label should be checked.
If you use both TK70 and TZ30 drives, remember that the TZ30 is unable to
read or write tapes that have originally been written by the TK70. However,
the TK70 can read tapes written by the TZ30 or the TK50.
Removable Storage Media
F-3