::Filename extension


Filename::windows    Files::names    Systems::command    Which::internet    Between::suffixes    Computer::using

A filename extension is an identifier specified as a suffix to the name by syntax, often separated from the base filename (by, e.g., a dot, a space), that indicates, e.g., the encoding (file format), the usage, of a computer file. Examples of filename extensions are .png, .jpeg, .exe, .dmg, and .txt.

Note that some systems might have multiple types of extension, e.g., in CMS CMS EXEC A1 has two extensions, the filetype EXEC and the filemodeUnknown extension tag "ref" A1.

Some file systems limit the length of the extension (such as the FAT file system from PC DOS/MS-DOS (without Long filename support) not allowing more than three characters and IBM's VM/CMS not allowing more than 8) while others (such as NTFS) do not. Unix filesystems accept the separator dot as a legal filename character.

Filename extension sections
Intro   Usage    Improvements    Command name issues    Security issues    Alternatives    See also    Notes    References    External links