ISO 9660 Support for CD-ROM

Microsoft Windows NT supports ISO 9660 CD-ROM format, but it does not support any of the RockRidge CD-ROM format extensions. ISO 9660 is an international standard that defines a file system for compact discs. Almost all systems support ISO 9660.

ISO 9660 Level 1 is similar to the MS-DOS file system. Filenames are limited to eight single-case characters, a period, and a three-character extension. Filenames cannot contain special or extended characters, (no hyphens, tildes, equal signs, or plus signs). Filenames can contain only single-case letters, numbers, and underscores. Directory names cannot contain three-digit extensions; they can contain only eight single-case characters.

All alphabetic characters are in uppercase letters; some software maps these to lowercase letters. Either the filename or the extension may be empty, but not both ("F." and ".E" are both legal filenames).

There is a "file version number" that can range from 1 to 32,767 and is separated from the extension by a semicolon. The file version number is ignored on many systems.

Subdirectories are allowed to nest up to eight levels deep.

ISO 9660 Level 2 allows longer filenames, up to 32 characters; however, most of the other restrictions still apply. Level 2 discs cannot be used on some systems, such as MS-DOS.

Windows NT 4.0 and Windows 2000 support Level 3 and allow for fragmented files, which is needed to support finalized packet-written disks. CD-ROM File System (CDFS) also supports Joliet extensions, which allows for longer file names and Unicode names.

Rock Ridge is not supported in Windows NT or Windows 2000.