Quantum Instruments DLT 7000 - Manual (Page 247)

SCSI Commands
Quantum DLT 7000 Tape System 5-143
RELEASE UNIT Command (17h) (continued)
Media Changer Considerations
The optional Element reservation feature defined for Medium Changer devices in
the SCSI-2 ANSI specification is not supported. The RELEASE command is
defined the same as for the tape drive. The whole loader unit can be released.
RESERVE / RELEASE of the Loader and Drive LUNs are handled
independently.