Editing File association (section)

===Mac OS===
The [[Classic Mac OS]] used [[type code]]s and [[creator code]]s to associate each file with its corresponding application, regardless of file extension. The more recent [[macOS]] also supports file extension–based associations.

Application bundles in macOS declare supported file types in their Info.plist file. For each of these specified types, a [[Uniform Type Identifier]] is given, along with a list of 'tags' which define how a file or data of this type could be identified. For example, the [[JPEG]] type is defined with a UTI of 'public.jpeg', and tagged with the extensions 'jpg' and 'jpeg', the [[MIME]] type 'image/jpeg' and the [[type code]] 'JPEG'.<ref>[https://developer.apple.com/mac/library/documentation/FileManagement/Conceptual/understanding_utis/understand_utis_conc/understand_utis_conc.html#//apple_ref/doc/uid/TP40001319-CH202-CHDHIJDE Mac OS X Reference Library - Uniform Type Identifier Concepts]</ref>

The operating system uses this information to generate a list of applications which are able to open each type. Within [[Finder (software)]] each file will be identified with a UTI and open with the default application for that type. The user may also select from a list of other applications which support the type.

Using this system, types are also associated with data for which there is no file name or the file extension is missing. This includes pasteboard data and data streaming over a protocol such as [[HTTP]] where a MIME type has been given.