Optical media

ISO9660

An outgrowth of the High Sierra and ECMA-119 (2nd Edition) specifications (the first edition wasn't widely implemented, and is useful only for historical value).

Joliet

A 1995 specification by Microsoft designed to address ISO9660:1988's shortcomings and restrictions regarding:

• Character set
• File name length (raised to 128 bytes from 30)
• Directory tree depth (eliminated 8-level hierarchy restriction, retains 240 total byte limit)
• Directory name format (raised to 128 bytes from 9660L2's 30, and adds file name extensions)
• Character sets ((almost) complete UCS-2 character set, using big-endian encoding)

Joliet implies use of ISO/IEC 10646 (UCS-2) in file naming, and can be detected by examining an ISO9660 SVD (Supplementary Volume Descriptor, ISO9660 section 8.5.6)'s "Escape Sequences" field for the UCS-2 escape sequences

• 25 2f 40,
• 25 2f 43, or
• 25 2f 45.

The following UCS-2 sequences are not allowed in a Joliet file name:

• All code points between 00 00 and 00 1f (control sequences)
• 00 2a (asterisk)
• 00 2f (forward slash)
• 00 3a (colon)
• 00 3b (semicolon)
• 00 3f (question mark)
• 00 5c (backslash)

El Torito

A 1995 specification by IBM and Phoenix for creating bootable ISO9660 CDROM's.

See Also

• The Linux CD-ROM HOWTO
• El Torito specification supplement, 2006-09-22