An ISO 9660 file system is a standard CD-ROM file system that allows you to read the same CD-ROM whether you're on a PC, Mac, or other major computer platform. The standard, issued in 1988, was written by an industry group named High Sierra. Almost all computers with CD-ROM drives can read files from an ISO 9660 file system.
There are several specification levels. In Level 1, file names must be in the 8.3 format (no more than eight characters in the name, no more than three characters in the suffix) and in capital letters. Directory names can be no longer than eight characters. There can be no more than eight nested directory levels. Level 2 and 3 specifications allow file names up to 32 characters long.