The standard specifies a very limited filename format. At its strictest interchange level, it only allows DOS-style "8.3" names, uppercase only. At less strict levels, filenames can be up to 31 characters. Several extensions, mainly Rock Ridge and Joliet, were developed to mitigate these limitations.
The filenames also have a VMS-style version number, so sometimes they are shown with a ";1" suffix.
The size of a file is limited to 4GB (2GB in some implementations). This is irrelevant with respect to CD-ROMs, because of their small capacity, but it is a reason to avoid using ISO 9660 on DVD-ROMs and other media. (A feature called "multiple extents" makes larger files possible, but support for it may be limited.)
Usually, the ASCII string "
CD001>" appears at offset 32769.
The first 32768 bytes are not used. Be aware that hybrid filesystems are possible. Just because something is a valid ISO 9660 image, doesn't mean it can't also be a valid file of some other type.
Some extensions to ISO 9660 are listed here.
See also: Wikipedia:Category:ISO 9660 extensions
Main article: System Use Sharing Protocol
Main article: Rock Ridge
Main article: Joliet
Main article: El Torito
CD-XA001" signature in volume descriptor, offset 1024.
AA" or "
BA" in directory record system use area.
Main article: zisofs
SUSP/Rock Ridge "
Mkisofs transparent compression
Main article: mkisofs transparent compression
SUSP/Rock Ridge "
RISC OS extensions
ARCHIMEDES" in directory record system use area.
Main article: TRANS.TBL
- ISO image
- Universal Disk Format (UDF) - A successor to ISO 9660
- Hybrids of Apple Partition Map and ISO 9660 are common.
- See Disk Image Formats#Optical Disc Image Formats for formats that might contain this format.
- 7-Zip, see here for an example
- isoinfo can perform basic operations and some validation.
- libcdio (
- Operating systems often include drivers for ISO 9660. On Linux, an ISO 9660 image file can be mounted using a loopback driver (
mount -t iso9660 -o loop ...).
- isolyzer is a tool that verifies if the file size of an ISO image is consistent with the information in its filesystem-level headers. This can be useful for detecting incomplete (e.g. truncated) ISO images. Apart from ISO 9660, isolyzer also supports UDF, HFS and HFS+, as well as hybrids of all of these filesystems.
- cdrkit → genisoimage
- Countless CD burning applications