ISO-9660 file system

File systems on CD-ROMs use the ISO-9660 file system, published by the International Organization for Standardization (ISO). This file system standard evolved from the High Sierra Format file system. It has three different levels for files:

  • Level 1 – supports only 8.3 filenames (eight characters with a three-character extension).
  • Level 2 – supports longer 32-character filenames.
  • Level 3 – supports longer 32-character filenames.


The Joliet extension provides support for long filenames using Windows. The Rock Ridge extensions provide support for long filenames, permissions, symbolic links, etc on Linux.
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