This article is from the CD-Recordable FAQ, by Andy McFadden (firstname.lastname@example.org) with numerous contributions by others.
UDF is an acronym for the humbly-named "Universal Disk Format". It's a
specification for a filesystem intended for use on write-once and
rewritable media. It's currently being used for DVD and some of the
CD-R/CD-RW packet writing software (e.g. Roxio DirectCD).
There have been four important releases of the specification:
- 1.02: first release; primarily useful for read-only media like DVD-ROM.
- 1.5: includes defect management, useful for CD-R and CD-RW.
- 2.0: adds support for Stream Files, Access Control Lists, and
- 2.01: adds support for Real Time Files.
- 2.5: adds Metadata Partition.
MacOS 8.1 and Win98 support UDF v1.02. Windows XP supports 1.02, 1.5,
and 2.01. To read UDF-format packet-written CD-R and CD-RW discs, you
need UDF v1.5 support. Roxio has made free UDF 1.5 drivers available for
Mac and Windows on their web site (check there for a list of supported
CD-ROM drives). Also, if you insert a disc formatted with DirectCD v3.0
or later into a Windows machine without a UDF reader, you will be offered
the opportunity to install one.
Download free UDF 1.5 drivers for MacOS and Win95/Win98/WinNT4 from
(The Windows driver appears to have moved; look at the bottom of
The technical specifications for the UDF filesystem can be found at
UDF is based on the ISO/IEC 13346 standard, now ECMA-167, available from
You can find Linux source code under development at
Philips has made UDF verification software available (source and binaries) at