8.3 is a common shorthand for the limits on filename length imposed by the FAT file system used by old versions of DOS and versions of Microsoft Windows prior to Windows 95 and Windows NT 3.5. Similar file naming schemes have also existed on earlier CP/M and on some Data General and Digital Equipment Corporation minicomputer operating systems. A filename is a special kind of string used to uniquely identify a file stored on the file system of a computer. ... File Allocation Table (FAT) is a partially patented file system developed by Microsoft for MS-DOS and is the primary file system for consumer versions of Microsoft Windows up to and including Windows Me. ... In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ... ‹ The template below has been proposed for deletion. ... Microsoft Windows is a family of operating systems by Microsoft. ... Windows 95 is a consumer-oriented graphical user interface-based operating system. ... Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... CP/M is an operating system originally created for Intel 8080/85 and Zilog Z80 based microcomputers by Gary Kildall of Digital Research, Inc. ... Data General was one of the first minicomputer firms from the late 1960s. ... Digital Equipment Corporation was a pioneering company in the American computer industry. ... Minicomputer (colloquially, mini) is a largely obsolete term for a class of multi-user computers which make up the middle range of the computing spectrum, in between the largest multi-user systems (traditionally, mainframe computers) and the smallest single-user systems (microcomputers or personal computers). ...

8.3 filenames have at most eight characters, optionally followed by a "." and a filename extension of at most three characters. For files with no extension the "." if present has no significance (that is "myfile" and "myfile." are equivalent). File and directory names are uppercase, although systems that use the 8.3 standard are usually case-insensitive. A filename extension is an extra set of (usually) alphanumeric characters that is appended to the end of a filename to allow computer users (as well as various pieces of software on the computer system) to quickly determine the type of data stored in the file. ... In computing, a directory, catalog, or folder, is an entity in a file system which can contain a group of files and/or other directories. ... Majuscules or capital letters (in the Roman alphabet: A, B, C, ...) are one type of case in a writing system. ...

VFAT, a variant of FAT with an extended directory format, was introduced in Windows 95 and Windows NT 3.5. It allowed much longer, mixed-case Unicode filenames (LFNs) in addition to classic 8.3 names. Windows 95 is a consumer-oriented graphical user interface-based operating system. ... Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... Because of technical limitations, some web browsers may not display some special characters in this article. ...

To maintain backward-compatibility with legacy applications (on DOS and Windows 3.1), an 8.3 filename is automatically generated for every LFN, through which the file can still be renamed, deleted or opened. ‹ The template below has been proposed for deletion. ...

Although there is no compulsory algorithm for creating the 8.3 name from an LFN, Windows uses the following convention: Flowcharts are often used to graphically represent algorithms. ...

1. If the LFN is 8.3 uppercase, no LFN will be stored on disk at all.
   • Example: "TEXTFILE.TXT"
2. If the LFN is 8.3 mixed case, the LFN will store the mixed-case name, while the 8.3 name will be an uppercased version of it.
   • Example: "TextFile.Txt" becomes "TEXTFILE.TXT".
3. The LFN is truncated to the first 6 letters of its basename, followed by a tilde, followed by a single digit, followed by the first 3 characters of the extension. The result is then stripped of invalid characters such as spaces and extra periods, while other characters such as (+) are changed to the underscore (_), and uppercased.
   • Example: "TextFile1.Mine.txt" becomes "TEXTFI~1.TXT" (or "TEXTFI~2.TXT", should "TEXTFI~1.TXT" already exist). "ver +1.2.text" becomes "VER_12~1.TEX".
4. Beginning with Windows 2000, if at least 4 files or folders already exist with the same initial 6 characters in their short names, the LFN is instead truncated to the first 2 letters of the basename (or 1 if the basename has only 1 letter), followed by 4 hexadecimal digits derived from an undocumented hash of the filename, followed by a tilde, followed by a single digit, followed by the first 3 characters of the extension. The result, as before, is stripped and uppercased.
   • Example: "TextFile.Mine.txt" becomes "TE021F~1.TXT".

The NTFS file system used by the Windows NT family supports LFNs natively, but 8.3 names are still available for legacy applications. This can be optionally disabled to increase performance. basename is a common program found on Unix systems. ... In mathematics and computer science, base-16, hexadecimal, or simply hex, is a numeral system with a radix or base of 16 usually written using the symbols 0–9 and A–F or a–f. ... NTFS or New Technology File System is the standard file system of Windows NT and its descendants: Windows 2000, Windows XP, Windows Server 2003 and Windows Vista. ... Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ...

The ISO 9660 file system (mainly used on compact discs) has similar limitations at the most basic Level 1, with the additional restriction that directory names cannot contain extensions and that some characters (notably hyphens) are not allowed in filenames. Level 2 allows filenames of up to 31 characters, more compatible with Mac OS file names. ISO 9660, a standard published by the International Organization for Standardization, defines a file system for CD-ROM media. ... A Compact Disc (CD) is an optical disc used to store digital data, originally developed for storing digital audio. ... A hyphen ( -, or ‐ ) is a punctuation mark. ... Mac OS, which stands for Macintosh Operating System, is a series of graphical user interface-based operating systems developed by Apple Computer for their Macintosh line of computer systems. ...

During the Microsoft antitrust trials, the names MICROS~1 and MICROS~2 were humorously used to refer to the companies that might exist after a proposed split of Microsoft. United States v. ...

External links

Large list of known 8.3 computer file extensions: File-extensions.org