Editing Universal Disk Format (section)

== Uses ==
While UDF was primarily developed for optical discs, it is also able to operate on other media such as hard disk drives and flash storage.<ref>{{cite web |url=https://www.man7.org/linux/man-pages/man8/mount.8.html |title=mount(8) – Linux manual page |access-date=2025-03-10 |quote=UDF is the "Universal Disk Format" filesystem defined by OSTA, the Optical Storage Technology Association, and is often used for DVD-ROM, frequently in the form of a hybrid UDF/ISO-9660 filesystem. It is, however, perfectly usable by itself on disk drives, flash drives and other block devices. }}</ref>

UDF was for well over a decade the only open-specification and [[cross-platform]]-supported file system without a file size limitation of 4 GiB (roughly 4.3 GB), until the open-sourcing of [[exFAT]] in 2019.{{efn|While [[ISO 9660]] is able to overcome its 4 GiB file size limitation by containing multiple file entries with the same name that refer to the same file (see [[ISO_9660#Directories_and_files|§ Directories and files]]), it is not well documented which operating systems support this feature, making its usefulness uncertain. Additionally, technical limitations make ISO 9660 unsuitable for hard disk and flash storage media anyway given that it was created only with factory-pressed [[CD-ROM]] that are never modified in mind. For example, files can not be added to an ISO 9660 file system without recreating it entirely or adding a new session (except if space was reserved for new files in advance on randomly writable media, but this hasn't been implemented so far as of 2025 given the lack of use), and the concept of multiple sessions does not exist on hard disks and flash storage given that they are randomly writable. }}  "Cross-platform" here means supported by all three majorly used operating systems, Windows and Mac OS and Linux.<!-- sorted by how widely they are in use in the consumer space --><ref>In August 2019, Microsoft decided to lift some legal restrictions to exFAT and release its official specifications: {{cite web |url=https://opensource.microsoft.com/blog/2019/08/28/exfat-linux-kernel/ |title=exFAT in the Linux kernel? Yes! |date=2019-08-28 |website=Microsoft Open Source Blog  |access-date=2025-03-10 |language=en-US |author=John Gossman  }}; {{cite web |url=https://www.techradar.com/news/microsoft-is-bringing-its-exfat-patents-to-linux-and-open-source |title=Microsoft is bringing its exFAT patents to Linux and open source  |website=Tech Radar |date=2019-08-29 |access-date=2025-03-10 |language=en-GB |author=Anthony Spadafora }}</ref>

On Windows, formatting flash storage devices as UDF can not be accomplished through the graphical formatting widget, only through the command prompt.<!-- Probably the same for HDD but not mentioned in source. --><ref>{{cite web |title=How To Format a Flash Drive as UDF (Windows 7 & 10 Solution) • |url=https://www.getusb.info:443/how-to-format-a-flash-drive-as-udf-windows-7-10-solution/ |website=USB Powered Gadgets and more.. |access-date=25 April 2025 |date=2 April 2020}}</ref>