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CD-ROM Volume and File Structure

Besides defining their physical structure and the raw recording structure of the bits, computer storage media require some specification of File Layout and Volume Structure. Essentially, they need a directory structure so that files can be laid out on the disc and organized by name. This structure for CD-ROM is commonly known as "ISO-9660", and sometimes still called the "High Sierra" standard.

The following quote is from the ECMA-130 CD-ROM specification.

In October 1985 a number of industrial and software companies in the USA invited experts to participate in the elaboration of a working paper describing a proposal for the volume and file structure of such disks. The result of this work ... was a report dated May 1986 and known as the “High Sierra Group” proposal. This proposal was submitted to ECMA for their consideration [which] led to the issue in December 1986 of Standard ECMA-119 [Volume and File Structure of CDROM for Information Interchange] which has been adopted by ISO as ECMA Standard ISO 9660.

So ECMA-119 is the same as ISO-9660. The term "High Sierra", by the way, comes from Del Webb's High Sierra Hotel and Casino in Reno, Nevada, the place where the meeting was held. There is also an extended standard called ECMA-168 which "can be used for both CD-ROM and CD-WO media for interchanging files. [ECMA-168] is seen as a revision and extension of ECMA-119 for CD-ROM applications because it has eliminated several restrictions and performance problems of ECMA-119." [ECMA-168, Brief History]. Copies of all ECMA standards are available at no charge from

To be continued... More info on ISO-9660 and ECMA-168.

Last Updated Monday October 15, 2001 17:58:38 PDT