Date: 9 February 1996

From: Howard Kaikow <kaikow@standards.com>

Subject: Birth Announcement: ISO/IEC 13346 and ISO/IEC 13490

The following 7 standards were published by ISO on 15 December 1995.

• ISO/IEC 13346-1:1995, Information technology - Volume and file structure of write-once and rewritable media using nonsequential recording for information interchange - Part 1: General.
• ISO/IEC 13346-2:1995, Information technology - Volume and file structure of write-once and rewritable media using nonsequential recording for information interchange - Part 2: Volume and boot block recognition.
• ISO/IEC 13346-3:1995, Information technology - Volume and file structure of write-once and rewritable media using nonsequential recording for information interchange - Part 3: Volume structure.
• ISO/IEC 13346-4:1995, Information technology - Volume and file structure of write-once and rewritable media using nonsequential recording for information interchange - Part 4: File structure.
• ISO/IEC 13346-5:1995, Information technology - Volume and file structure of write-once and rewritable media using nonsequential recording for information interchange - Part 5: Record structure.
• ISO/IEC 13490-1:1995, Information technology - Volume and file structure of read-only and write-once compact disk media for information interchange - Part 1: General.
• ISO/IEC 13490-2:1995, Information technology - Volume and file structure of read-only and write-once compact disk media for information interchange - Part 2: Volume and file structure.

In effect, ISO/IEC 13490 may be viewed as the successor to ISO 9660:1988, Information processing Volume and file structure of CD-ROM for information interchange. In particular, ISO/IEC 13490 corrects all of the known shortcomings of ISO 9660, including: allowing long filenames, removing the restrictions on the depth of a directory hierarchy, providing for multibyte character sets, providing for Posix attributes, allowing for incremental recording and specifying how multisession is to be used.

ISO/IEC 13346 and ISO/IEC 13490 are very much interrelated in that they use common specifications for nearly everything that they have in common (of course, there are a few exceptions to make life (more) interesting).

Most importantly, it must be noted that these standards underwent significant editorial changes from the last draft to correct errors and ambiguities. These documents should be more consistent than ISO 9660 ever was.

The following is from the Scope of ISO/IEC 13490-1:

ISO/IEC 13490 specifies a format and associated system requirements for volume and boot block recognition, volume structure, file structure and record structure for the interchange of information between users of information processing systems using CD-WO (a write-once compact disk medium), hybrid CD-WO (a write-once compact disk with a read-only area) and CD-ROM disks.

NOTE 1 - CD-WO is an evolution of CD-ROM technology which allows the recording of information on a write-once compact disk medium.

The volume and boot block recognition is specified in ISO/IEC 13346-2. The record structure is specified in ISO/IEC 13346-5.

NOTE 2 - A volume set may be recorded that is in conformance with both ISO 9660 and ISO/IEC 13490. ISO/IEC 13490 is an enhancement of ISO 9660. ISO/IEC 13490 allows greater information interchange using CD-ROM. In addition, it supports incremental recording and updating of information stored on a CD-WO disk. Under certain restrictions (see 2/B.2.1), all of the files may be read by both a receiving system conforming to ISO 9660 and by a receiving system conforming to ISO/IEC 13490.

The following is from the Scope of ISO/IEC 13346-1:

ISO/IEC 13346 specifies a format and associated system requirements for volume and boot block recognition, volume structure, file structure and record structure for the interchange of information on media between users of information processing systems.

The media shall be recorded as if the recording of sectors may be done in any order.

NOTE 1 - The medium is not restricted to being of only one type; the type of medium may be either write once, or read only, or rewritable, or a combination of these types.

As I was incestuously involved in the design and writing of these standards, and I am self-employed, I am in a unique position to assist vendors and users in achieving consistent implementations of these standards, avoiding the mess that arose when the High Sierra format and ISO 9660 were first implemented, indeed some of those problems still exist. If your organization is interested in my assistance, you may contact me via email at kaikow@standards.com.