What is ECMA 168?

ECMA 168 is a volume and file format standard for write-once CD and CD-ROM. It was approved as a European standard by the ECMA General Assembly in June of 1992. It provides for full Orange Book functionality, including multisession recording, track-at-once recording, and packet recording. When used with an Orange Book writer, this will allow write-once CD to be used more like a general-purpose storage peripheral than is possible using ISO 9660. ECMA 168 also incorporates the functionality of Rock Ridge: the ability to use Unix-style filenames, Unix permissions, and deep directory hierarchies. Much thought was put into character set issues, and ECMA 168 accommodates multiple-byte character sets such as ISO 10646. Although ECMA 168 is not upward-compatible with ISO 9660, it is possible to write a "conformant disc" containing both sets of volume and file structures. If such a disc is Yellow Book compatible (a CD-ROM or a CD-WO written disc-at-once), it could be read on either an ISO 9660 system or an ECMA 168 system. There are many common elements between ECMA 168 and ECMA 167, which is a new standard intended primarily for WORM and erasable optical disks. Hopefully this will encourage developers to support both standards.

The title of the standard is "Volume and File Structure of Read-Only and Write-Once Compact Disc Media for Information Interchange". This standard expands upon the ISO-9660 CD-ROM standard.

At the current time, I do not know of any companies which support ECMA 168 in their products.

A new draft international standard on CD-ROM/CD-WO format:

ISO/IEC DIS 13490 Volume and File Structure of Read-only and Write-once Compact Disc Media for Information Interchange is currently undergoing letter ballot process and voting may end at end of August, 1993.

DIS 13490 is also the ECMA Standard 168, which is derived from the Frankfurt Group proposal. Copies of this draft standard should be available at the ANSI or ECMA office.

DIS 13490 is designed to support both the CD-ROM (yellow book) and CD-WO (orange book) conforming media. In addition, DIS 13490 removed many unnecessary restrictions of ISO 9660, and is compatible with ISO 9660 at the directory and file structures level. DIS 13490 conforming discs can also be made to be read by both ISO 9660 and DIS 13490 conforming receiving systems.

The ECMA 168 specification is available by anonymous ftp from ftp.cdrom.com in the directory pub/cdrom/ecma168.



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