The Rock Ridge Interchange Protocol ( also Rockridge Rockridge CD or Extension) is an extension of ISO -9660 CD -ROM file system for Unix derivatives.
In Rock Ridge file system in addition to the ISO9660 filesystem Unix typical Unix file permissions, file owner / group file, inode number are managed ( for hard links ), link count, and symbolic links. In addition, file names are supported with up to 255 characters in length. All characters except ' /' and the NUL character ('\ 0' ) are possible, the directory structure can take any depth. The additional sophisticated metadata are stored in contrast to Joliet of Microsoft, within the normal ISO 9660 file structure.
There was also an extension by Amiga Rock Ridge. This has been used by some burning programs under AmigaOS, to save the amiga- typical file permissions on CD. Since the AmigaOS was not designed as a multiuser system, the users have been ignored.