This standard defines the command set extensions to facilitate operation of the sequential-access device type. This standard, implemented in conjunction with the requirements of the SCSI Architecture Model - 4 standard and the applicable clauses of the SCSI Primary Commands - 4 standard, fully specify the standard command set for the sequential-access device type.

The objectives of this standard are to provide the following:

a) permit an application client to communicate over a SCSI service delivery subsystem, with a logical unit that declares itself to be a sequential-access device in the PERIPHERAL DEVICE TYPE field of the standard INQUIRY data (see SPC-4);

b) define commands unique to the sequential-access device type; and

c) define commands to manage the operation of the sequential-access device type.

The roadmap in figure 1 is intended to show the general applicability of the documents to one another. The figure is not intended to imply a relationship such as a hierarchy, protocol stack, or system architecture. It specifies the applicability of a standard to the implementation of a given SCSI protocol.

This standard makes obsolete the following concepts from previous versions of this standard:

a) the GAP SIZE field;

b) RSMK and setmarks; and

c) Attached Media Changer model.

The term SCSI is used to refer to the family of standards described in this clause.