ISO 9660 is an International Standards Organization (ISO) standard for a universal file system for CDs and DVDs that can be read by various operating systems. ISO 9660 is based on the High Sierra format and is platform-independent, so that the CD file systems can be read by personalcomputers, MAC computers and Unix computers.
The ISO 9660/XA extension added multisession capability to the standard. DVDs usually have ISO 9660 in addition to Universal Disk Format( UDF) to allow older operating system versions to access the data. Three different levels have been defined by the International Standards Organization (ISO)
Level 1 has the format XXXXXXXX.XXX;N, where x can take the digits from 0 to 9 and all letters of the alphabet; N the digits between 1 and 32,767. Level 1 is based on file naming conventions such as the file allocation table( FAT)
Level 2 is more universal in file names and their length. It allows special characters and a file name length of up to 31 characters.
Level 3 allows file names up to 128 characters in length.
The extension for file names of ISO 9660 is done by the Joliet format.