Universal Disk Format
vendor-neutral file system, used in practice for DVDs and other optical discs
Universal Disk Format (UDF) is an open, vendor-neutral file system for computer data storage for a broad range of media. In practice, it has been most widely used for DVDs and newer optical disc formats, supplanting ISO 9660. Due to its design, it is very well suited to incremental updates on both write-once and re-writable optical media. UDF was developed and maintained by the Optical Storage Technology Association (OSTA).
In engineering terms, Universal Disk Format is a profile of the specifications known as ISO/IEC 13346 and ECMA-167.
Usage
Normally, authoring software will master a UDF file system in a batch process and write it to optical media in a single pass. But when packet writing to rewritable media, such as CD-RW, UDF allows files to be created, deleted and changed on-disc just as a general-purpose filesystem would on removable media like floppy disks and flash drives. This is also possible on write-once media, such as CD-R, but in that case the space occupied by the deleted files cannot be reclaimed (and instead becomes inaccessible).
Multi-session mastering is also possible in UDF, though some implementations may be unable to read disks with multiple sessions.
History
The Optical Storage Technology Association standardized the UDF file system to form a common file system for all optical media: both for read-only media and for re-writable optical media.
“Universal Disk Format” enters the record as vendor-neutral file system, used in practice for DVDs and other optical discs. Crown Archives preserves that source wording while asking what Universal, Disk and Format can confirm, complicate or overturn.
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This entry incorporates text from “Universal Disk Format” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.