![]() Additionally, a creator code was specified to determine which application would be launched when the file's icon was double-clicked. The classic Mac OS disposed of filename-based extension metadata entirely it used, instead, a distinct file type code to identify the file format. The assumption was still that any extension represented a single file type there was an unambiguous mapping between extension and icon. Microsoft Windows allowed multiple applications to be associated with a given extension, and different actions were available for selecting the required application, such as a context menu offering a choice between viewing, editing or printing the file. With the advent of graphical user interfaces, the issue of file management and interface behavior arose. The VFAT, NTFS, and ReFS file systems for Windows also do not separate the extension metadata from the rest of the file name, and allow multiple extensions. This model generally requires the full filename to be provided in commands, whereas the metadata approach often allows the extension to be omitted. It is more common, especially in binary files, for the file itself to contain internal metadata describing its contents. Programs transforming or creating files may add the appropriate extension to names inferred from input file names (unless explicitly given an output file name), but programs reading files usually ignore the information it is mostly intended for the human user. gz indicates that the tar archive file is compressed with gzip). tar indicates that the file is a tar archive of one or more files, and the. More than one extension usually represents nested transformations, such as (the. Sometimes it is said to have more than one extension, although terminology varies in this regard, and most authors define extension in a way that doesn't allow more than one in the same file name. The dot character is just another character in the main filename. ![]() ![]() In OS/360 and successors, the part of the dataset name following the last period, called the low level qualifier, is treated as an extension by some software, e.g., TSO EDIT, but it has no special significance to the operating system itself the same applies to Unix files in MVS.įilesystems for UNIX-like operating systems do not separate the extension metadata from the rest of the file name. Under Microsoft's DOS and Windows, extensions such as EXE, COM or BAT indicate that a file is a program executable. On file systems of some mainframe systems such as CMS in VM, VMS, and of PC systems such as CP/M and derivative systems such as MS-DOS, the extension is a separate namespace from the filename. The exact definition, giving the criteria for deciding what part of the file name is its extension, belongs to the rules of the specific filesystem used usually the extension is the substring which follows the last occurrence, if any, of the dot character ( example: txt is the extension of the filename readme.txt, and html the extension of ). They are commonly used to imply information about the way data might be stored in the file. ![]() Some file systems implement filename extensions as a feature of the file system itself and may limit the length and format of the extension, while others treat filename extensions as part of the filename without special distinction.įilename extensions may be considered a type of metadata. Other extension formats include dashes and/or underscores on early versions of Linux and some versions of IBM AIX. A filename extension is typically delimited from the rest of the filename with a full stop (period), but in some systems it is separated with spaces. The extension indicates a characteristic of the file contents or its intended use. ![]() JSTOR ( November 2015) ( Learn how and when to remove this template message)Ī filename extension, file name extension or file extension is a suffix to the name of a computer file (e.g.Unsourced material may be challenged and removed.įind sources: "Filename extension" – news Please help improve this article by adding citations to reliable sources. Var ans = parseInt(document.getElementById('txt1').This article needs additional citations for verification. ![]()
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