Product manual

3.6 Group 2, 3 and 4 commands
Group 2, 3 and 4 commands are 10-byte commands. Group 2 commands
are are not implemented. Group 3 and 4 commands are reserved. If the
drive receives one of these commands, it returns a check condition
status.
Note. Do not use Group 3 and 4 commands. If you do, you may destroy
data on the disc.
3.7 Group 5 and 6 commands
Group 5 and 6 commands are 12-byte commands. Group 5 commands
are not implemented. If the drive receives a Group 5 command, it returns
a check condition status. Group 6 commands are reserved for Seagate
use.
Note. Do not use Group 6 commands. If you do, you may destroy data
on the disc.
3.8 Group 7 commands
Group 7 commands are 10-byte commands. These commands are not
implemented. If the drive receives one of these commands, it returns a
check condition status.
ST3655 Family SCSI Drives Product Manual, Rev. A 75