This standard specifies the functional requirements for the SCSI Block Commands - 3 (SBC-3) command set. SBC-3 permits SCSI block logical units such as rigid disks to attach to computers and provides the definition for their use. This standard maintains a high degree of compatibility with the SCSI Block Commands (SBC-2) command set, INCITS 405-2005, and while providing additional functions, is not intended to require changes to presently installed devices or existing software.