Editing FourCC (section)

==Common uses==
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One of the most well-known uses of FourCCs is to identify the [[video codec]] or [[video coding format]] in AVI files. Common identifiers include ''[[DivX|DIVX]]'', ''[[Xvid|XVID]]'', and ''[[H.264/MPEG-4 AVC|H264]]''. For [[audio coding format]]s, AVI and WAV files use a two-byte identifier, usually written in [[hexadecimal]] (such as ''0055'' for [[MP3]]). In QuickTime files, these two-byte identifiers are prefixed with the letters "ms" to form a four-character code. [[RealMedia]] files also use four-character codes, however, the actual codes used differ from those found in AVI or QuickTime files.

Other file formats that make important use of the four-byte ID concept are the [[MIDI|Standard MIDI File (SMF)]] format, the [[Portable Network Graphics|PNG]] image file format, the [[.3ds|3DS]] (3D Studio Max) mesh file format and the [[International Color Consortium|ICC]] profile format.

Four-character codes are also used in applications other than file formats, for example:
* UEFI Forum for vendor in the ACPI ID Registry<ref>{{cite web|title=ACPI ID Registry|url=http://www.uefi.org/acpi_id_list|website=uefi.org}}</ref>
* ACPI specification defines four-character identifiers in ACPI Source Language (ASL)
* Synopsys to tell component ID via registers of an IP (DesignWare collection)

Other uses for OSTypes include:
* as record field IDs and event type and class IDs in [[AppleEvents]]
* for identifying components in the [[Component Manager]]
* as “atom” IDs in the [[QuickTime]] movie and image file formats
* as a localization-independent way of identifying standard folders in the Folder Manager
* in [[QuickDraw GX]], they were used as gxTag types and also as types of collection items in the Collection Manager.
* [[Enumerated type|Enumeration]] constants in Apple APIs (as an integer; host endianess)
* "OSStatus" [[error code]]s in certain libraries, such as QuickTime (as an integer; host endianess)<ref>{{cite web |title=OSStatus — Apple API Errors |url=https://www.osstatus.com/search/results?platform=all&framework=all&search=who%3F |website=www.osstatus.com}}</ref>