# ASCII

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Character encoding standard

This article is about the 7-bit character encoding standard. For other uses, see [ASCII (disambiguation)](/source/ASCII_(disambiguation)). Not to be confused with 8-bit [extended ASCIIs](/source/Extended_ASCII).

ASCII ASCII chart from MIL-STD-188-100 (1972) MIME / IANA us-ascii Alias(es) ISO-IR-006,[1] ANSI_X3.4-1968, ANSI_X3.4-1986, ISO_646.irv:1991, ISO646-US, us, IBM367, cp367[2] Languages primarily English; also supports Malay, Rotokas, Interlingua, Ido, and X-SAMPA Classification ISO/IEC 646 series Extensions Unicode ISO/IEC 8859 (series) KOI-8 OEM (series) Windows-125x (series) Others Preceded by ITA 2, FIELDATA Succeeded by ISO/IEC 8859, ISO/IEC 10646 (Unicode)

**ASCII** ([/ˈæski/](https://en.wikipedia.org/wiki/Help:IPA/English) [ⓘ](https://en.wikipedia.org/wiki/File:En-us-ASCII.ogg) [*ASS-kee*](https://en.wikipedia.org/wiki/Help:Pronunciation_respelling_key)),[3]: 6 an acronym for **American Standard Code for Information Interchange**, is a [character encoding](/source/Character_encoding) standard for representing a particular set of 95 ([English-language](/source/English_language)–focused) [printable](/source/Printable_character) and 33 [control](/source/Control_character) characters – a total of 128 [code points](/source/Code_point). The set of available punctuation had significant impact on the syntax of computer languages and text markup. ASCII hugely influenced the design of character sets used by modern computers; for example, the first 128 code points of [Unicode](/source/Unicode) are the same as ASCII.

ASCII encodes each code-point as a value from 0 to 127 – storable as a seven-[bit](/source/Bit) [integer](/source/Integer).[4] Ninety-five code-points are printable, including digits *0* to *9*, lowercase letters *a* to *z*, uppercase letters *A* to *Z*, and commonly used [punctuation symbols](/source/Punctuation_symbol). For example, the letter i is represented as 105 ([decimal](/source/Decimal)). Also, ASCII specifies 33 non-printing [control codes](/source/Control_code) which originated with [Teletype devices](/source/Teletype_Corporation#Teletype_Corporation), most of which are now obsolete.[5] The control characters that are still commonly used include [carriage return](/source/Carriage_return), [line feed](/source/Line_feed), and [tab](/source/Tab_key#Tab_characters).

ASCII lacks code-points for characters with [diacritical marks](/source/Diacritical_mark) and therefore does not directly support [terms or names](/source/English_terms_with_diacritical_marks) such as [résumé](/source/R%C3%A9sum%C3%A9), [jalapeño](/source/Jalape%C3%B1o), or [René](/source/Ren%C3%A9). But, depending on hardware and software support, some diacritical marks can be [rendered](/source/Rendering_(computer_graphics)) by overwriting a letter with a [backtick](/source/Backtick) (`) or [tilde](/source/Tilde) (~).

The [Internet Assigned Numbers Authority](/source/Internet_Assigned_Numbers_Authority) (IANA) prefers the name **US-ASCII** for this character encoding.[2]

ASCII is one of the [IEEE milestones](/source/List_of_IEEE_Milestones).[6]

## History

ASCII is the standardisation of a seven-[bit](/source/Bit) [teleprinter](/source/Teleprinter) code developed in part from earlier [telegraph codes](/source/Telegraph_code).

Work on the ASCII standard began in May 1961, when [IBM](/source/IBM) engineer [Bob Bemer](/source/Bob_Bemer) submitted a proposal to the American Standards Association's (ASA) (now the [American National Standards Institute](/source/American_National_Standards_Institute) or ANSI) X3.2 subcommittee.[7] The first edition of the standard was published in 1963,[8] contemporaneously with the introduction of the [Teletype Model 33](/source/Teletype_Model_33). It later underwent a major revision in 1967,[9][10] and several further revisions until 1986.[11] In contrast to earlier telegraph codes such as [Baudot](/source/Baudot_code), ASCII was ordered for more convenient collation (especially alphabetical sorting of lists), and added controls for devices other than teleprinters.[11]

ASCII (1963). [Control Pictures](/source/Control_Pictures) of equivalent controls are shown where they exist, or a grey dot otherwise.

ASCII was developed under the auspices of a committee of the American Standards Association (ASA), called the X3 committee, by its X3.2 (later X3L2) subcommittee, and later by that subcommittee's X3.2.4 working group (now [INCITS](/source/INCITS)). The ASA later became the United States of America Standards Institute (USASI)[3]: 211 and ultimately became the [American National Standards Institute](/source/American_National_Standards_Institute) (ANSI).

With the other special characters and control codes filled in, ASCII was published as ASA X3.4-1963,[8][12] leaving 28 code positions without any assigned meaning, reserved for future standardization, and one unassigned control code.[3]: 66, 245 There was some debate at the time whether there should be more control characters rather than the lowercase alphabet.[3]: 435 The indecision did not last long: during May 1963 the CCITT Working Party on the New Telegraph Alphabet proposed to assign lowercase characters to *sticks*[a][13] 6 and 7,[14] and [International Organization for Standardization](/source/International_Organization_for_Standardization) TC 97 SC 2 voted during October to incorporate the change into its draft standard.[15] The X3.2.4 task group voted its approval for the change to ASCII at its May 1963 meeting.[16] Locating the lowercase letters in *sticks*[a][13] 6 and 7 caused the characters to differ in bit pattern from the upper case by a single bit, which simplified [case-insensitive](/source/Case-insensitive) character matching and the construction of keyboards and printers.

The X3 committee made other changes. It added the [brace](/source/Brace_(punctuation)) and [vertical bar](/source/Vertical_bar) characters.[17] It renamed some control characters – SOM became [SOH](/source/Start-of-Header). It moved or removed others – RU was removed.[3]: 247–248 ASCII was subsequently updated as USAS X3.4-1967,[9][18] then USAS X3.4-1968,[19] ANSI X3.4-1977, and finally, ANSI X3.4-1986.[11][20]

The use of ASCII format for Network Interchange was described in 1969.[21] That document was formally elevated to an Internet Standard in 2015.[22]

## Revisions

- ASA X3.4-1963[3][8][18][20]

- ASA X3.4-1965 (approved, but not published, nevertheless used by [IBM 2260](/source/IBM_2260) & [2265](/source/IBM_2265) Display Stations and [IBM 2848](/source/IBM_2848) Display Control)[3]: 423, 425–428, 435–439[23][18][20]

- USAS X3.4-1967[3][9][20]

- USAS X3.4-1968[3][19][20]

- ANSI X3.4-1977[20]

- ANSI X3.4-1986[11][20]

- ANSI X3.4-1986 (R1992)

- ANSI X3.4-1986 (R1997)

- ANSI INCITS 4-1986 (R2002)[24]

- ANSI INCITS 4-1986 (R2007)[25]

- INCITS 4-1986 (R2012)[26]

- INCITS 4-1986 (R2017)[27]

- INCITS 4-1986 (R2022)[28]

In the X3.15 standard, the X3 committee also addressed how ASCII should be transmitted ([least significant bit](/source/Least_significant_bit) first)[3]: 249–253[29] and recorded on perforated tape. They proposed a [9-track](/source/9-track) standard for magnetic tape and attempted to deal with some [punched card](/source/Punched_card) formats.

## Design considerations

### Bit width

The X3.2 subcommittee designed ASCII based on the earlier teleprinter encoding systems. Like other [character encodings](/source/Character_encoding), ASCII specifies a correspondence between digital bit patterns and [character](/source/Character_(computing)) symbols (i.e. [graphemes](/source/Grapheme) and [control characters](/source/Control_character)). This allows [digital](/source/Digital_data) devices to communicate with each other and to process, store, and communicate character-oriented information such as written language. Before ASCII was developed, the encodings in use included 26 [alphabetic](/source/English_alphabet) characters, 10 [numerical digits](/source/Numerical_digit), and from 11 to 25 special graphic symbols. To include all these, and control characters compatible with the [Comité Consultatif International Téléphonique et Télégraphique](/source/CCITT) (CCITT) [International Telegraph Alphabet No. 2](/source/International_Telegraph_Alphabet_No._2) (ITA2) standard of 1932,[30][31] [FIELDATA](/source/FIELDATA) (1956[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]), and early [EBCDIC](/source/EBCDIC) (1963), more than 64 codes were required for ASCII.

ITA2 was in turn based on [Baudot code](/source/Baudot_code), the 5-bit telegraph code Émile Baudot invented in 1870 and patented in 1874.[31]

The committee debated the possibility of a [shift](/source/Shift_code) function (like in [ITA2](/source/ITA2)), which would allow more than 64 codes to be represented by a [six-bit code](/source/Six-bit_character_code). In a shifted code, some character codes determine choices between options for the following character codes. It allows compact encoding, but is less reliable for [data transmission](/source/Data_transmission), as an error in transmitting the shift code typically makes a long part of the transmission unreadable. The standards committee decided against shifting, and so ASCII required at least a seven-bit code.[3]: 215 §13.6, 236 §4

The committee considered an eight-bit code, since eight bits ([octets](/source/Octet_(computing))) would allow two four-bit patterns to efficiently encode two digits with [binary-coded decimal](/source/Binary-coded_decimal). However, it would require all data transmission to send eight bits when seven could suffice. The committee voted to use a seven-bit code to minimize costs associated with data transmission. Since perforated tape at the time could record eight bits in one position, it also allowed for a [parity bit](/source/Parity_bit) for [error checking](/source/Error_checking) if desired.[3]: 217 §c, 236 §5 [Eight-bit](/source/8-bit_computing) machines (with octets as the native data type) that did not use parity checking typically set the eighth bit to 0.[32]

### Internal organization

The code itself was patterned so that most control codes were together and all graphic codes were together, for ease of identification. The first two so-called *ASCII sticks*[a][13] (32 positions) were reserved for control characters.[3]: 220, 236 8, 9) The ["space" character](/source/Space_(punctuation)) had to come before graphics to make [sorting](/source/Sorting_algorithm) easier, so it became position 20[hex](/source/Hexadecimal);[3]: 237 §10 for the same reason, many special signs commonly used as separators were placed before digits. The committee decided it was important to support uppercase [64-character alphabets](/source/Sixbit_code_pages), and chose to pattern ASCII so it could be reduced easily to a usable 64-character set of graphic codes,[3]: 228, 237 §14 as was done in the [DEC SIXBIT](/source/DEC_SIXBIT) code (1963). [Lowercase](/source/Lower_case) letters were therefore not interleaved with [uppercase](/source/Uppercase). To keep options available for lowercase letters and other graphics, the special and numeric codes were arranged before the letters, and the letter *A* was placed in position 41[hex](/source/Hexadecimal) to match the draft of the corresponding British standard.[3]: 238 §18 The digits 0–9 are prefixed with 011, but the remaining [4 bits](/source/Nibble) correspond to their respective values in binary, making conversion with [binary-coded decimal](/source/Binary-coded_decimal) straightforward (for example, 5 is encoded to 011*0101*, where 5 is *0101* in binary).

Many of the non-alphanumeric characters were positioned to correspond to their shifted position on typewriters; an important subtlety is that these were based on *mechanical* typewriters, not *electric* typewriters.[33] Mechanical typewriters followed the [*de facto* standard](/source/De_facto_standard) set by the [Remington No. 2](/source/Remington_No._2) (1878), the first typewriter with a shift key, and the shifted values of 23456789- were "#$%_&'() – early typewriters omitted *0* and *1*, using *O* (capital letter *o*) and *l* (lowercase letter *L*) instead, but 1! and 0) pairs became standard once 0 and 1 became common. Thus, in ASCII !"#$% were placed in the second stick,[a][13] positions 1–5, corresponding to the digits 1–5 in the adjacent stick.[a][13] The parentheses could not correspond to *9* and *0*, however, because the place corresponding to *0* was taken by the space character. This was accommodated by removing _ (underscore) from *6* and shifting the remaining characters, which corresponded to many European typewriters that placed the parentheses with *8* and *9*. This discrepancy from typewriters led to [bit-paired keyboards](/source/Bit-paired_keyboard), notably the [Teletype Model 33](/source/Teletype_Model_33), which used the left-shifted layout corresponding to ASCII, differently from traditional mechanical typewriters.

Electric typewriters, notably the [IBM Selectric](/source/IBM_Selectric) (1961), used a somewhat different layout that has become *de facto* standard on computers – following the [IBM PC](/source/IBM_PC) (1981), especially [Model M](/source/Model_M) (1984) – and thus shift values for symbols on modern keyboards do not correspond as closely to the ASCII table as earlier keyboards did. The /? pair also dates to the No. 2, and the ,< .> pairs were used on some keyboards (others, including the No. 2, did not shift , (comma) or . (full stop) so they could be used in uppercase without unshifting). However, ASCII split the ;: pair (dating to No. 2), and rearranged mathematical symbols (varied conventions, commonly -* =+) to :* ;+ -=.

Some then-common typewriter characters were not included, notably ½ ¼ ¢, while ^ ` ~ were included as diacritics for international use, and < > for mathematical use, together with the simple line characters \ | (in addition to common /). The *@* symbol was not used in continental Europe and the committee expected it would be replaced by an accented *À* in the French variation, so the *@* was placed in position 40[hex](/source/Hexadecimal), right before the letter A.[3]: 243

The control codes felt essential for data transmission were the start of message (SOM), end of address (EOA), [end of message](/source/End_of_message) (EOM), end of transmission (EOT), "who are you?" (WRU), "are you?" (RU), a reserved device control (DC0), synchronous idle (SYNC), and acknowledge (ACK). These were positioned to maximize the [Hamming distance](/source/Hamming_distance) between their bit patterns.[3]: 243–245

### Character order

ASCII-code order is also called *ASCIIbetical* order.[34] [Collation](/source/Collation) of data is sometimes done in this order rather than "standard" alphabetical order ([collating sequence](/source/Collating_sequence)). The main deviations in ASCII order are:

- All uppercase come before lowercase letters; for example, "Z" precedes "a"

- Digits and many punctuation marks come before letters

An intermediate order converts uppercase letters to lowercase before comparing ASCII values.

## Character set

ASCII (1977/1986) 0 1 2 3 4 5 6 7 8 9 A B C D E F 0x NUL SOH STX ETX EOT ENQ ACK BEL BS HT LF VT FF CR SO SI 1x DLE DC1 DC2 DC3 DC4 NAK SYN ETB CAN EM SUB ESC FS GS RS US 2x SP ! " # $ % & ' ( ) * + , - . / 3x 0 1 2 3 4 5 6 7 8 9 : ; < = > ? 4x @ A B C D E F G H I J K L M N O 5x P Q R S T U V W X Y Z [ \ ] ^ _ 6x ` a b c d e f g h i j k l m n o 7x p q r s t u v w x y z { | } ~ DEL Changed or added in 1963 version Changed in both 1963 version and 1965 draft

## Character groups

### Control characters

Early symbols assigned to the 32 control characters, space and delete characters ([ISO 2047](/source/ISO_2047), MIL-STD-188-100, 1972)

Main article: [C0 control codes](/source/C0_control_codes)

ASCII reserves the first 32 [code points](/source/Code_point) (numbers 0–31 decimal) and the last one (number 127 decimal) for [control characters](/source/Control_character). These are codes intended to control [peripheral devices](/source/Peripheral_device) (such as [printers](/source/Computer_printer)), or to provide [meta-information](/source/Metadata) about data streams, such as those stored on magnetic tape. Despite their name, these code points do not represent printable characters (i.e. they are not characters at all, but signals). For debugging purposes, "placeholder" symbols (such as those given in [ISO 2047](/source/ISO_2047) and its predecessors) are assigned to them.

For example, character 0x0A represents the "line feed" function (which causes a printer to advance its paper), and character 8 represents "[backspace](/source/Backspace)". [RFC](/source/RFC_(identifier)) [2822](https://www.rfc-editor.org/rfc/rfc2822) refers to control characters that do not include carriage return, line feed or [white space](/source/Whitespace_(computer_science)) as non-whitespace control characters.[35] Except for the control characters that prescribe elementary line-oriented formatting, ASCII does not define any mechanism for describing the structure or appearance of text within a document. Other schemes, such as [markup languages](/source/Markup_language), address page and document layout and formatting.

The original ASCII standard used only short descriptive phrases for each control character. The ambiguity this caused was sometimes intentional,[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] such as when a character would be used slightly differently on a terminal link or in a [data stream](/source/Data_stream).

Probably the most influential single device affecting the interpretation of these characters was the [Teletype Model 33](/source/Teletype_Model_33) ASR, which was a printing terminal with an available [paper tape](/source/Punched_tape) reader/punch option. Paper tape was a very popular medium for long-term program storage until the 1980s, less costly and in some ways less fragile than magnetic tape. In particular, the Teletype Model 33 machine assignments for codes 17 (control-Q, DC1, also known as XON), 19 (control-S, DC3, also known as XOFF), and 127 ([delete](/source/Delete_key)) became *de facto* standards. The Model 33 was also notable for taking the description of control-G (code 7, BEL, meaning audibly alert the operator) literally, as the unit contained an actual bell which it rang when it received a BEL character. Because the keytop for the O key also showed a left-arrow symbol (from ASCII-1963, which had this character instead of [underscore](/source/Underscore)), a noncompliant use of code 15 (control-O, shift in) interpreted as "delete previous character" was also adopted by many early timesharing systems but eventually became neglected.

When a Teletype 33 ASR equipped with the automatic paper tape reader received a control-S (XOFF, an abbreviation for transmit off), it caused the tape reader to stop; receiving control-Q (XON, transmit on) caused the tape reader to resume. This so-called [flow control](/source/Flow_control_(data)) technique became adopted by several early computer operating systems as a "handshaking" signal warning a sender to stop transmission because of impending [buffer overflow](/source/Buffer_overflow); it persists to this day in many systems as a manual output control technique. On some systems, control-S retains its meaning, but control-Q is replaced by a second control-S to resume output.

The 33 ASR also could be configured to employ control-R (DC2) and control-T (DC4) to start and stop the tape punch; on some units equipped with this function, the corresponding control character lettering on the keycap above the letter was TAPE and TAPE respectively.[36]

#### Delete vs backspace

The Teletype could not move its typehead backwards, so it did not have a key on its keyboard to send a BS (backspace). Instead, there was a key marked RUB OUT that sent code 127 (DEL). The purpose of this key was to erase mistakes in a manually-input paper tape: the operator had to push a button on the tape punch to back it up, then type the rubout, which punched all holes and replaced the mistake with a character that was intended to be ignored.[37] Teletypes were commonly used with the less-expensive computers from [Digital Equipment Corporation](/source/Digital_Equipment_Corporation) (DEC); these systems had to use what keys were available, and thus the DEL character was assigned to erase the previous character.[38][39] Because of this, DEC video terminals (by default) sent the DEL character for the key marked "Backspace" while the separate key marked "Delete" sent an [escape sequence](/source/Escape_sequence); many other competing terminals sent a BS character for the backspace key.

The early Unix tty drivers, unlike some modern implementations, allowed only one character to be set to erase the previous character in canonical input processing (where a very simple line editor is available); this could be set to BS *or* DEL, but not both, resulting in recurring situations of ambiguity where users had to decide depending on what terminal they were using ([shells](/source/Shell_(computing)) that allow line editing, such as [ksh](/source/KornShell), [bash](/source/Bash_(Unix_shell)), and [zsh](/source/Z_shell), understand both). The assumption that no key sent a BS character allowed Ctrl+H to be used for other purposes, such as the "help" prefix command in [GNU Emacs](/source/GNU_Emacs).[40]

#### Escape

Many more of the control characters have been assigned meanings quite different from their original ones. The "escape" character (ESC, code 27), for example, was intended originally to allow sending of other control characters as literals instead of invoking their meaning, an "escape sequence". This is the same meaning of "escape" encountered in URL encodings, [C language](/source/C_(programming_language)) strings, and other systems where certain characters have a reserved meaning. Over time this interpretation has been co-opted and has eventually been changed.

In modern usage, an ESC sent *to* the terminal usually indicates the start of a command sequence, which can be used to address the cursor, scroll a region, set/query various terminal properties, and more. They are usually in the form of a so-called "[ANSI escape code](/source/ANSI_escape_code)" (often starting with a "[Control Sequence Introducer](/source/Control_Sequence_Introducer)", "CSI", "ESC [") from [ECMA-48](/source/ECMA-48) (1972) and its successors. Some escape sequences do not have introducers, like the "Reset to Initial State", "RIS" command "ESC c".[41]

In contrast, an ESC read *from* the terminal is most often used as an [out-of-band](/source/Out-of-band_data) character used to terminate an operation or special mode, as in the [TECO](/source/Text_Editor_and_Corrector) and [vi](/source/Vi_(text_editor)) [text editors](/source/Text_editor). In [graphical user interface](/source/Graphical_user_interface) (GUI) and [windowing](/source/Window_(computing)) systems, ESC generally causes an application to abort its current operation or to [exit](/source/Exit_(system_call)) (terminate) altogether.

#### End of line

The reapplication of some control characters to new meanings created problems when transferring "plain text" files between systems. The best example of this is the [newline](/source/Newline) problem in various [operating systems](/source/Operating_system). Teletype machines required that a line of text be terminated with a "carriage return" (to move the printhead to the beginning of the line) followed by a "line feed" (to advance the paper by one line). The name "carriage return" comes from the fact that, on a manual [typewriter](/source/Typewriter), the carriage holding the paper moves while the typebars that strike the ribbon remain stationary. The entire carriage must be pushed to the right ("returned") in order to position the paper for the next line.

DEC operating systems ([OS/8](/source/OS%2F8), [RT-11](/source/RT-11), [RSX-11](/source/RSX-11), [RSTS](/source/RSTS%2FE), [TOPS-10](/source/TOPS-10), etc.) stored both characters at the end of each line in textual files, as needed by Teletype machines. When so-called "glass TTYs" were introduced (later called CRTs or "dumb terminals"), they followed the same logic, expecting the same CR and LF characters. When [Gary Kildall](/source/Gary_Kildall) created [CP/M](/source/CP%2FM), he was inspired by some of the command line interface conventions used in DEC's RT-11 operating system.

Until the introduction of [IBM PC DOS](/source/IBM_PC_DOS) in 1981, [IBM](/source/IBM) had no influence in this, because their 1970s operating systems used EBCDIC encoding instead of ASCII and they were oriented toward punch-card input and line printer output on which the concept of "carriage return" was meaningless. IBM's PC DOS (also marketed as [MS-DOS](/source/MS-DOS) by Microsoft) inherited the CRLF convention by virtue of being loosely based on CP/M,[42] and [Windows](/source/Windows), in turn, inherited it from MS-DOS.

Placing CR and LF at the end of each line in a [plain text](/source/Plain_text) document or data stream reflects what terminals and printers needed to receive, to display that material. [Multics](/source/Multics) introduced an innovation: it used only one character (LF), to represent the end of the line in stored files and in data streams.[43]: 357 Upon output, the tty driver converts the LF to CRLF, so files can be printed to a terminal without needing a command to explicitly convert the file format. [Unix](/source/Unix) and [Unix-like](/source/Unix-like) systems adopted this design from Multics, as did [Amiga](/source/Amiga) systems. [UNIX](/source/UNIX) documents say "newline" or "NL" to refer to the line terminator. Contrarily, the Radio Shack [TRS-80](/source/TRS-80), [Apple DOS](/source/Apple_DOS), [Apple ProDOS](/source/Apple_ProDOS), and [classic Mac OS](/source/Classic_Mac_OS) used a lone carriage return (CR) to terminate lines. Apple's later operating system, Mac OS X (now called [macOS](/source/MacOS)) is based on Unix, so it uses line feed (LF).

Computers attached to the [ARPANET](/source/ARPANET) included machines running operating systems such as TOPS-10 and [TENEX](/source/TENEX_(operating_system)), which used CR-LF line endings; operating systems such as Multics, which used LF line endings; and operating systems such as [OS/360](/source/OS%2F360), which represented lines as a character count followed by the characters of the line and which used EBCDIC rather than ASCII encoding. To enable communication between all these systems, the [Telnet](/source/Telnet) protocol defined a "Network Virtual Terminal" (NVT), wherein a single text format (ASCII with CR-LF line endings) was used for transmission and each system converted to/from its own native representation.[44]

The [File Transfer Protocol](/source/File_Transfer_Protocol) adopted the Telnet protocol, including the Network Virtual Terminal, for transmitting commands and for transferring textual files (known as "ASCII mode").[45][46] Internet E-mail is built atop the NVT.[47] The World Wide Web's [HTTP](/source/HTTP) uses a modified NVT: the standard allows lone CR and LF characters but requires that each be interpreted as an NVT CRLF.[48]

Complexity arose in network-facing systems that didn't follow the NVT mechanism, such as some version control systems.[49] Bugs sometimes expose a system's native implementation to other systems on the Internet, causing data corruption.[50]

#### End of file/stream

The PDP-6 monitor,[38] and its PDP-10 successor TOPS-10,[39] used control-Z (SUB) as an end-of-file indication for input from a terminal. Some operating systems such as CP/M tracked file length only in units of disk blocks, and used control-Z to mark the end of the actual text in the file.[51] For these reasons, EOF, or [end-of-file](/source/End-of-file), was used colloquially and conventionally as a [three-letter acronym](/source/Three-letter_acronym) for control-Z instead of SUBstitute. The end-of-text character ([ETX](/source/End-of-text_character)), also known as [control-C](/source/Control-C), was inappropriate for a variety of reasons, while using control-Z as the control character to end a file is analogous to the letter Z's position at the end of the alphabet, and serves as a very convenient [mnemonic aid](/source/Mnemonic_device). A historically common and still prevalent convention uses the ETX character convention to interrupt and halt a program via an input data stream, usually from a keyboard.

The Unix terminal driver uses the end-of-transmission character ([EOT](/source/End-of-Transmission_character)), also known as control-D, to indicate the end of a data stream.

In the [C programming language](/source/C_programming_language), and in Unix conventions, the [null character](/source/Null_character) is used to terminate text [strings](/source/String_(computer_science)); such [null-terminated strings](/source/Null-terminated_string) can be known in abbreviation as ASCIZ or ASCIIZ, where here Z stands for "zero".

## Table of codes

### Control code table

Binary Oct Dec Hex Abbreviation Unicode Control Pictures[b] Caret notation[c] C escape sequence[d] Name (1967) 1963 1965 1967 000 0000 000 0 00 NULL NUL ␀ ^@ \0[e] Null 000 0001 001 1 01 SOM SOH ␁ ^A Start of Heading 000 0010 002 2 02 EOA STX ␂ ^B Start of Text 000 0011 003 3 03 EOM ETX ␃ ^C End of Text 000 0100 004 4 04 EOT ␄ ^D End of Transmission 000 0101 005 5 05 WRU ENQ ␅ ^E Enquiry 000 0110 006 6 06 RU ACK ␆ ^F Acknowledgement 000 0111 007 7 07 BELL BEL ␇ ^G \a Bell (Alert) 000 1000 010 8 08 FE0 BS ␈ ^H \b Backspace[f][g] 000 1001 011 9 09 HT/SK HT ␉ ^I \t Horizontal Tab[h] 000 1010 012 10 0A LF ␊ ^J \n Line Feed 000 1011 013 11 0B VTAB VT ␋ ^K \v Vertical Tab 000 1100 014 12 0C FF ␌ ^L \f Form Feed 000 1101 015 13 0D CR ␍ ^M \r Carriage Return[i] 000 1110 016 14 0E SO ␎ ^N Shift Out 000 1111 017 15 0F SI ␏ ^O Shift In 001 0000 020 16 10 DC0 DLE ␐ ^P Data Link Escape 001 0001 021 17 11 DC1 ␑ ^Q Device Control 1 (often XON) 001 0010 022 18 12 DC2 ␒ ^R Device Control 2 001 0011 023 19 13 DC3 ␓ ^S Device Control 3 (often XOFF) 001 0100 024 20 14 DC4 ␔ ^T Device Control 4 001 0101 025 21 15 ERR NAK ␕ ^U Negative Acknowledgement 001 0110 026 22 16 SYNC SYN ␖ ^V Synchronous Idle 001 0111 027 23 17 LEM ETB ␗ ^W End of Transmission Block 001 1000 030 24 18 S0 CAN ␘ ^X Cancel 001 1001 031 25 19 S1 EM ␙ ^Y End of Medium 001 1010 032 26 1A S2 SS SUB ␚ ^Z Substitute 001 1011 033 27 1B S3 ESC ␛ ^[ \e[j] Escape[k] 001 1100 034 28 1C S4 FS ␜ ^\ File Separator 001 1101 035 29 1D S5 GS ␝ ^] Group Separator 001 1110 036 30 1E S6 RS ␞ ^^[l] Record Separator 001 1111 037 31 1F S7 US ␟ ^_ Unit Separator 111 1111 177 127 7F DEL ␡ ^? Delete[m][g]

Other representations might be used by specialist equipment, for example [ISO 2047](/source/ISO_2047) graphics or [hexadecimal](/source/Hexadecimal) numbers.

### Printable character table

At the time of adoption, the codes 20hex to 7Ehex would cause the printing of a visible character (a glyph), and thus were designated "printable characters". These codes represent letters, digits, [punctuation marks](/source/Punctuation_mark), and a few miscellaneous symbols. There are 95 printable characters in total.[n]

The empty space between words, as produced by the space bar of a keyboard, is character code 20hex. Since the space character is visible in printed text it considered a "printable character", even though it is unique in having no visible glyph. It is listed in the printable character table, as per the ASCII standard, instead of in the control character table.[3]: 223[21]

Code 7Fhex corresponds to the non-printable "delete" (DEL) control character and is listed in the control character table.

Earlier versions of ASCII used the up arrow instead of the [caret](/source/Caret) (5Ehex) and the left arrow instead of the underscore (5Fhex).[8][52]

Binary Oct Dec Hex Glyph 1963 1965 1967 010 0000 040 32 20 space (no visible glyph) 010 0001 041 33 21 ! 010 0010 042 34 22 " 010 0011 043 35 23 # 010 0100 044 36 24 $ 010 0101 045 37 25 % 010 0110 046 38 26 & 010 0111 047 39 27 ' 010 1000 050 40 28 ( 010 1001 051 41 29 ) 010 1010 052 42 2A * 010 1011 053 43 2B + 010 1100 054 44 2C , 010 1101 055 45 2D - 010 1110 056 46 2E . 010 1111 057 47 2F / 011 0000 060 48 30 0 011 0001 061 49 31 1 011 0010 062 50 32 2 011 0011 063 51 33 3 011 0100 064 52 34 4 011 0101 065 53 35 5 011 0110 066 54 36 6 011 0111 067 55 37 7 011 1000 070 56 38 8 011 1001 071 57 39 9 011 1010 072 58 3A : 011 1011 073 59 3B ; 011 1100 074 60 3C < 011 1101 075 61 3D = 011 1110 076 62 3E > 011 1111 077 63 3F ? 100 0000 100 64 40 @ ` @ 100 0001 101 65 41 A 100 0010 102 66 42 B 100 0011 103 67 43 C 100 0100 104 68 44 D 100 0101 105 69 45 E 100 0110 106 70 46 F 100 0111 107 71 47 G 100 1000 110 72 48 H 100 1001 111 73 49 I 100 1010 112 74 4A J 100 1011 113 75 4B K 100 1100 114 76 4C L 100 1101 115 77 4D M 100 1110 116 78 4E N 100 1111 117 79 4F O 101 0000 120 80 50 P 101 0001 121 81 51 Q 101 0010 122 82 52 R 101 0011 123 83 53 S 101 0100 124 84 54 T 101 0101 125 85 55 U 101 0110 126 86 56 V 101 0111 127 87 57 W 101 1000 130 88 58 X 101 1001 131 89 59 Y 101 1010 132 90 5A Z 101 1011 133 91 5B [ 101 1100 134 92 5C \ ~ \ 101 1101 135 93 5D ] 101 1110 136 94 5E ↑ ^ 101 1111 137 95 5F ← _ 110 0000 140 96 60 @ ` 110 0001 141 97 61 a 110 0010 142 98 62 b 110 0011 143 99 63 c 110 0100 144 100 64 d 110 0101 145 101 65 e 110 0110 146 102 66 f 110 0111 147 103 67 g 110 1000 150 104 68 h 110 1001 151 105 69 i 110 1010 152 106 6A j 110 1011 153 107 6B k 110 1100 154 108 6C l 110 1101 155 109 6D m 110 1110 156 110 6E n 110 1111 157 111 6F o 111 0000 160 112 70 p 111 0001 161 113 71 q 111 0010 162 114 72 r 111 0011 163 115 73 s 111 0100 164 116 74 t 111 0101 165 117 75 u 111 0110 166 118 76 v 111 0111 167 119 77 w 111 1000 170 120 78 x 111 1001 171 121 79 y 111 1010 172 122 7A z 111 1011 173 123 7B { 111 1100 174 124 7C ACK ¬ | 111 1101 175 125 7D } 111 1110 176 126 7E ESC | ~

## Usage

ASCII was first used commercially during 1963 as a seven-bit teleprinter code for [American Telephone & Telegraph](/source/American_Telephone_%26_Telegraph)'s TWX (TeletypeWriter eXchange) network. TWX originally used the earlier five-bit [ITA2](/source/ITA2), which was also used by the competing [Telex](/source/Telex) teleprinter system. [Bob Bemer](/source/Robert_William_Bemer) introduced features such as the [escape sequence](/source/Escape_character).[7] His British colleague [Hugh McGregor Ross](/source/Hugh_McGregor_Ross) helped to popularize this work – according to Bemer, "so much so that the code that was to become ASCII was first called the *Bemer–Ross Code* in Europe".[53] Because of his extensive work on ASCII, Bemer has been called "the father of ASCII".[54]

On March 11, 1968, US President [Lyndon B. Johnson](/source/Lyndon_B._Johnson) mandated that all computers purchased by the [United States Federal Government](/source/United_States_Federal_Government) support ASCII, stating:[55][56][57]

I have also approved recommendations of the [Secretary of Commerce](/source/Secretary_of_Commerce) [[Luther H. Hodges](/source/Luther_H._Hodges)] regarding standards for recording the Standard Code for Information Interchange on magnetic tapes and paper tapes when they are used in computer operations. All computers and related equipment configurations brought into the Federal Government inventory on and after July 1, 1969, must have the capability to use the Standard Code for Information Interchange and the formats prescribed by the magnetic tape and paper tape standards when these media are used.

ASCII was the most common character encoding on the [World Wide Web](/source/World_Wide_Web) until December 2007, when the [UTF-8](/source/UTF-8) encoding surpassed it; UTF-8 is [backward compatible](/source/Backward_compatible) with ASCII.[58][59][60]

## Variants and derivations

As computer technology spread throughout the world, different [standards bodies](/source/Standardization) and corporations developed many variations of ASCII to facilitate the expression of non-English languages that used Roman-based alphabets. One could class some of these variations as "[ASCII extensions](/source/ASCII_extension)", although some misuse that term to represent all variants, including those that do not preserve ASCII's character-map in the 7-bit range. Furthermore, the ASCII extensions have also been mislabelled as ASCII.

### 7-bit codes

Main articles: [ISO/IEC 646](/source/ISO%2FIEC_646) and [ITU T.50](/source/ITU_T.50)

See also: [UTF-7](/source/UTF-7)

From early in its development,[61] ASCII was intended to be just one of several national variants of an international character code standard.

Other international standards bodies have ratified character encodings such as [ISO 646](/source/ISO_646) (1967) that are identical or nearly identical to ASCII, with extensions for characters outside the English [alphabet](/source/Alphabet) and symbols used outside the United States, such as the symbol for the United Kingdom's [pound sterling](/source/Pound_sterling) (£) seen in [code page 1104](/source/Code_page_1104). Almost every country needed an adapted version of ASCII, since ASCII suited the needs of only the US and a few other countries. For example, Canada had its own version that supported French characters.

Many other countries developed variants of ASCII to include non-English letters (e.g. [é](/source/%C3%89), [ñ](/source/%C3%91), [ß](/source/%C3%9F), [Ł](/source/%C5%81)), currency symbols (e.g. [£](/source/%C2%A3), [¥](/source/%C2%A5)), etc. See also [YUSCII](/source/YUSCII) (Yugoslavia).

It would share most characters in common, but assign other locally useful characters to several [code points](/source/Code_point) reserved for "national use". However, the four years that elapsed between the publication of ASCII-1963 and ISO's first acceptance of an international recommendation during 1967[62] caused ASCII's choices for the national use characters to seem to be *de facto* standards for the world, causing confusion and incompatibility once other countries did begin to make their own assignments to these code points.

ISO/IEC 646, like ASCII, is a 7-bit character set. It does not make any additional codes available, so the same code points encoded different characters in different countries. Escape codes were defined to indicate which national variant applied to a piece of text, but they were rarely used, so it was often impossible to know what variant to work with and, therefore, which character a code represented, and in general, text-processing systems could cope with only one variant anyway.

Because the bracket and brace characters of ASCII were assigned to "national use" code points that were used for accented letters in other national variants of ISO/IEC 646, a German, French, or Swedish, etc. programmer using their national variant of ISO/IEC 646, rather than ASCII, had to write, and thus read, something such as

ä aÄiÜ = 'Ön'; ü

instead of

{ a[i] = '\n'; }

[C trigraphs](/source/C_trigraph) were created to solve this problem for [ANSI C](/source/ANSI_C), although their late introduction and inconsistent implementation in compilers limited their use. Many programmers kept their computers on ASCII, so plain-text in Swedish, German etc. (for example, in e-mail or [Usenet](/source/Usenet)) contained "{, }" and similar variants in the middle of words, something those programmers got used to. For example, a Swedish programmer mailing another programmer asking if they should go for lunch, could get "N{ jag har sm|rg}sar" as the answer, which should be "Nä jag har smörgåsar" meaning "No I've got sandwiches".

In Japan and Korea, still as of the 2020s,[\[update\]](https://en.wikipedia.org/w/index.php?title=ASCII&action=edit) a variation of ASCII is used, in which the [backslash](/source/Backslash) (5C hex) is rendered as ¥ (a [Yen sign](/source/Yen_sign), in Japan) or ₩ (a [Won sign](/source/Won_sign), in Korea). This means that, for example, the file path C:\Users\Smith is shown as C:¥Users¥Smith (in Japan) or C:₩Users₩Smith (in Korea).

In Europe, [teletext character sets](/source/Teletext_character_set), which are variants of ASCII, are used for broadcast TV subtitles, defined by [World System Teletext](/source/World_System_Teletext) and broadcast using the DVB-TXT standard for embedding teletext into DVB transmissions.[63] In the case that the subtitles were initially authored for teletext and converted, the derived subtitle formats are constrained to the same character sets.

### 8-bit codes

Main article: [Extended ASCII](/source/Extended_ASCII)

See also: [ISO/IEC 8859](/source/ISO%2FIEC_8859) and [UTF-8](/source/UTF-8)

Eventually, as 8-, [16-](/source/16-bit_computing), and [32-bit](/source/32-bit_computing) (and later [64-bit](/source/64-bit_computing)) computers began to replace [12-](/source/12-bit_computing), [18-](/source/18-bit_computing), and [36-bit](/source/36-bit_computing) computers as the norm, it became common to use an 8-bit byte to store each character in memory, providing an opportunity for extended, 8-bit relatives of ASCII. In most cases these developed as true extensions of ASCII, leaving the original character-mapping intact, but adding additional character definitions after the first 128 (i.e., 7-bit) characters. ASCII itself remained a seven-bit code: the term "extended ASCII" has no official status.

For some countries, 8-bit extensions of ASCII were developed that included support for characters used in local languages (for example, [ISCII](/source/ISCII) for India and [VISCII](/source/VISCII) for Vietnam).

Even for markets where it was not necessary to add many characters to support additional languages, manufacturers of early home computer systems often developed their own 8-bit extensions of ASCII to include additional characters, such as [box-drawing characters](/source/Box-drawing_characters), [semigraphics](/source/Semigraphics), and [video game sprites](/source/Sprite_(computer_graphics)). Often, these additions also replaced control characters (index 0 to 31, as well as index 127) with even more platform-specific extensions. In other cases, the extra bit was used for some other purpose, such as toggling [inverse video](/source/Inverse_video); this approach was used by [ATASCII](/source/ATASCII), an extension of ASCII developed by [Atari](/source/Atari).

Most ASCII extensions are based on ASCII-1967 (the current standard), but some extensions are instead based on the earlier ASCII-1963. For example, [PETSCII](/source/PETSCII), which was developed by [Commodore International](/source/Commodore_International) for their [8-bit](/source/8-bit_computing) systems, is based on ASCII-1963. Likewise, many [Sharp MZ character sets](/source/Sharp_MZ_character_set) are based on ASCII-1963.

IBM defined [code page 437](/source/Code_page_437) for the [IBM PC](/source/IBM_PC), replacing the control characters with graphic symbols such as [smiley faces](/source/Emoticon), and mapping additional graphic characters to the upper 128 positions.[64] [Digital Equipment Corporation](/source/Digital_Equipment_Corporation) developed the [Multinational Character Set](/source/Multinational_Character_Set) (DEC-MCS) for use in the popular [VT220](/source/VT220) [terminal](/source/Computer_terminal) as one of the first extensions designed more for international languages than for block graphics. [Apple](/source/Apple_Inc.) defined [Mac OS Roman](/source/Mac_OS_Roman) for the Macintosh and [Adobe](/source/Adobe_Inc.) defined the [PostScript Standard Encoding](/source/PostScript_Standard_Encoding) for [PostScript](/source/PostScript); both sets contained "international" letters, typographic symbols and punctuation marks instead of graphics, more like modern character sets.

The [ISO/IEC 8859](/source/ISO%2FIEC_8859) standard (derived from the DEC-MCS) provided a standard that most systems copied (or at least were based on, when not copied exactly). A popular further extension designed by Microsoft, [Windows-1252](/source/Windows-1252) (often mislabeled as [ISO-8859-1](/source/ISO-8859-1)), added the typographic punctuation marks needed for traditional text printing. ISO-8859-1, Windows-1252, and the original 7-bit ASCII were the most common character encoding methods on the [World Wide Web](/source/World_Wide_Web) until 2008, when [UTF-8](/source/UTF-8) overtook them.[59]

[ISO/IEC 4873](/source/ISO%2FIEC_4873) introduced 32 additional control codes defined in the 80–9F [hexadecimal](/source/Hexadecimal) range, as part of extending the 7-bit ASCII encoding to become an 8-bit system.[65]

### Unicode

Main articles: [Unicode](/source/Unicode) and [ISO/IEC 10646](/source/ISO%2FIEC_10646)

See also: [Basic Latin (Unicode block)](/source/Basic_Latin_(Unicode_block))

[Unicode](/source/Unicode) and the ISO/IEC 10646 [Universal Character Set](/source/Universal_Character_Set) (UCS) have a much wider array of characters and their various encoding forms have begun to supplant ISO/IEC 8859 and ASCII rapidly in many environments. While ASCII is limited to 128 characters, Unicode and the UCS support more characters by separating the concepts of unique identification (using [natural numbers](/source/Natural_number) called *code points*) and encoding (to 8-, 16-, or 32-bit binary formats, called [UTF-8](/source/UTF-8), [UTF-16](/source/UTF-16), and [UTF-32](/source/UTF-32), respectively).

ASCII was incorporated into the Unicode (1991) character set as the first 128 symbols, so the 7-bit ASCII characters have the same numeric codes in both sets. This allows [UTF-8](/source/UTF-8) to be [backward compatible](/source/Backward_compatibility) with 7-bit ASCII, as a UTF-8 file containing only ASCII characters is identical to an ASCII file containing the same sequence of characters. Even more importantly, [forward compatibility](/source/Forward_compatibility) is ensured as software that recognizes only 7-bit ASCII characters as special and does not alter bytes with the highest bit set (as is often done to support 8-bit ASCII extensions such as ISO-8859-1) will preserve UTF-8 data unchanged.[66]

## See also

- [3568 ASCII](/source/3568_ASCII) – AsteroidPages displaying short descriptions with no spaces

- [Alt codes](/source/Alt_codes) – Input methodPages displaying short descriptions of redirect targets

- [ASCII art](/source/ASCII_art) – Computer art form using text characters

- [ASCII ribbon campaign](/source/ASCII_ribbon_campaign) – Campaign for plain text (only) emails

- [Basic Latin (Unicode block)](/source/Basic_Latin_(Unicode_block))

- [Extended ASCII](/source/Extended_ASCII) – Nickname for 8-bit ASCII-derived character sets

- [HTML decimal character rendering](/source/HTML_decimal_character_rendering) – Use of encoding systems for international characters in HTMLPages displaying short descriptions of redirect targets

- [Jargon file](/source/Jargon_file) – Collection of definitions from computer subculturesPages displaying short descriptions of redirect targets

- [Text file](/source/Text_file) – Computer file containing plain text

- [List of computer character sets](/source/List_of_computer_character_sets)

- [List of Unicode characters](/source/List_of_Unicode_characters)

## Notes

1. ^ [***a***](#cite_ref-NB_Stick_14-0) [***b***](#cite_ref-NB_Stick_14-1) [***c***](#cite_ref-NB_Stick_14-2) [***d***](#cite_ref-NB_Stick_14-3) [***e***](#cite_ref-NB_Stick_14-4) The 128 characters of the 7-bit ASCII character set are divided into eight 16-character groups called *sticks* 0–7, associated with the three [most-significant bits](/source/Most-significant_bit).[13] Depending on the horizontal or vertical representation of the character map, *sticks* can correspond with either table rows or columns.

1. **[^](#cite_ref-53)** The Unicode characters from the "Control Pictures" area U+2400 to U+2421 reserved for representing control characters when it is necessary to print or display them rather than have them perform their intended function. Some browsers may not display these properly.

1. **[^](#cite_ref-54)** Caret notation is often used to represent control characters on a terminal. On most text terminals, holding down the [Ctrl](/source/Control_key) key while typing the second character will type the control character. Sometimes the shift key is not needed, for instance ^@ may be typable with just Ctrl+2 or Ctrl+Space.

1. **[^](#cite_ref-55)** Character escape sequences in C programming language and many other languages influenced by it, such as [Java](/source/Java_(programming_language)) and [Perl](/source/Perl) (though not all implementations necessarily support all escape sequences).

1. **[^](#cite_ref-56)** Entering any Single-Byte character is supported by escaping its octal value. However, because of the role of NULL in [C-strings](/source/Null-terminated_string), this case see particular use.

1. **[^](#cite_ref-57)** The [Backspace](/source/Backspace) character can also be entered by pressing the ← Backspace key on some systems.

1. ^ [***a***](#cite_ref-bsp_del_mismatch_58-0) [***b***](#cite_ref-bsp_del_mismatch_58-1) The ambiguity of [Backspace](/source/Backspace) is due to early terminals designed assuming the main use of the keyboard would be to manually punch paper tape while not connected to a computer. To delete the previous character, one had to back up the paper tape punch, which for mechanical and simplicity reasons was a button on the punch itself and not the keyboard, then type the rubout character. They therefore placed a key producing rubout at the location used on typewriters for backspace. When systems used these terminals and provided command-line editing, they had to use the "rubout" code to perform a backspace, and often did not interpret the backspace character (they might echo "^H" for backspace). Other terminals not designed for paper tape made the key at this location produce Backspace, and systems designed for these used that character to back up. Since the delete code often produced a backspace effect, this also forced terminal manufacturers to make any Delete key produce something other than the Delete character.

1. **[^](#cite_ref-59)** The [Tab character](/source/Tab_character) can also be entered by pressing the Tab ↹ key on most systems.

1. **[^](#cite_ref-60)** The [Carriage Return](/source/Carriage_Return) character can also be entered by pressing the ↵ Enter or Return key on most systems.

1. **[^](#cite_ref-61)** The \e [escape sequence](/source/Escape_sequence) is not part of [ISO C](/source/ISO_C) and many other language specifications. However, it is understood by several compilers, including [GCC](/source/GCC_(software)).

1. **[^](#cite_ref-62)** The [Escape character](/source/Escape_character) can also be entered by pressing the Esc key on some systems.

1. **[^](#cite_ref-63)** ^^ means Ctrl+^ (pressing the "Ctrl" and [caret](/source/Caret) keys).

1. **[^](#cite_ref-64)** The [Delete character](/source/Delete_character) can sometimes be entered by pressing the ← Backspace key on some systems.

1. **[^](#cite_ref-65)** Printed out, the characters are: !"#$%&'()*+,-./0123456789:;<=>?​@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_​`abcdefghijklmnopqrstuvwxyz{|}~

## References

1. **[^](#cite_ref-1)** [ANSI](/source/American_National_Standards_Institute) (1975-12-01). [*ISO-IR-6: ASCII Graphic character set*](https://itscj.ipsj.or.jp/ir/006.pdf) (PDF). ITSCJ/[IPSJ](/source/Information_Processing_Society_of_Japan).

1. ^ [***a***](#cite_ref-IANA_2007_2-0) [***b***](#cite_ref-IANA_2007_2-1) ["Character Sets"](https://www.iana.org/assignments/character-sets). *Internet Assigned Numbers Authority (IANA)*. 2007-05-14. Retrieved 2019-08-25.

1. ^ [***a***](#cite_ref-Mackenzie_1980_3-0) [***b***](#cite_ref-Mackenzie_1980_3-1) [***c***](#cite_ref-Mackenzie_1980_3-2) [***d***](#cite_ref-Mackenzie_1980_3-3) [***e***](#cite_ref-Mackenzie_1980_3-4) [***f***](#cite_ref-Mackenzie_1980_3-5) [***g***](#cite_ref-Mackenzie_1980_3-6) [***h***](#cite_ref-Mackenzie_1980_3-7) [***i***](#cite_ref-Mackenzie_1980_3-8) [***j***](#cite_ref-Mackenzie_1980_3-9) [***k***](#cite_ref-Mackenzie_1980_3-10) [***l***](#cite_ref-Mackenzie_1980_3-11) [***m***](#cite_ref-Mackenzie_1980_3-12) [***n***](#cite_ref-Mackenzie_1980_3-13) [***o***](#cite_ref-Mackenzie_1980_3-14) [***p***](#cite_ref-Mackenzie_1980_3-15) [***q***](#cite_ref-Mackenzie_1980_3-16) [***r***](#cite_ref-Mackenzie_1980_3-17) [***s***](#cite_ref-Mackenzie_1980_3-18) Mackenzie, Charles E. (1980). [*Coded Character Sets, History and Development*](https://textfiles.meulie.net/bitsaved/Books/Mackenzie_CodedCharSets.pdf) (PDF). The Systems Programming Series (1 ed.). [Addison-Wesley Publishing Company, Inc.](/source/Addison-Wesley_Publishing_Company%2C_Inc.) pp. 6, 66, 211, 215, 217, 220, 223, 228, 236–238, 243–245, 247–253, 423, 425–428, 435–439. [ISBN](/source/ISBN_(identifier)) [978-0-201-14460-4](https://en.wikipedia.org/wiki/Special:BookSources/978-0-201-14460-4). [LCCN](/source/LCCN_(identifier)) [77-90165](https://lccn.loc.gov/77-90165). [Archived](https://web.archive.org/web/20160526172151/https://textfiles.meulie.net/bitsaved/Books/Mackenzie_CodedCharSets.pdf) (PDF) from the original on May 26, 2016. Retrieved August 25, 2019.

1. **[^](#cite_ref-RFC-4949_4-0)** Shirley, R. (August 2007). [*Internet Security Glossary, Version 2*](https://www.rfc-editor.org/rfc/rfc4949). [IETF](/source/Internet_Engineering_Task_Force). [doi](/source/Doi_(identifier)):[10.17487/RFC4949](https://doi.org/10.17487%2FRFC4949). [RFC](/source/Request_for_Comments) [4949](https://datatracker.ietf.org/doc/html/rfc4949). Retrieved 2016-06-13.

1. **[^](#cite_ref-Maini_2007_5-0)** Maini, Anil Kumar (2007). [*Digital Electronics: Principles, Devices and Applications*](https://books.google.com/books?id=NQSpNAEACAAJ&pg=PA28). [John Wiley and Sons](/source/John_Wiley_and_Sons). p. 28. [ISBN](/source/ISBN_(identifier)) [978-0-470-03214-5](https://en.wikipedia.org/wiki/Special:BookSources/978-0-470-03214-5). In addition, it defines codes for 33 nonprinting, mostly obsolete control characters that affect how the text is processed.

1. **[^](#cite_ref-6)** ["Milestone-Proposal:ASCII MIlestone - IEEE NJ Coast Section"](https://ieeemilestones.ethw.org/Milestone-Proposal:ASCII_MIlestone_-_IEEE_NJ_Coast_Section). *IEEE Milestones Wiki*. 2016-03-29. Retrieved 2024-02-26.

1. ^ [***a***](#cite_ref-Brandel_1999_7-0) [***b***](#cite_ref-Brandel_1999_7-1) Brandel, Mary (1999-07-06). ["1963: The Debut of ASCII"](https://web.archive.org/web/20130617155922/http://edition.cnn.com/TECH/computing/9907/06/1963.idg/). [CNN](/source/CNN). Archived from [the original](http://edition.cnn.com/TECH/computing/9907/06/1963.idg/) on 2013-06-17. Retrieved 2008-04-14.

1. ^ [***a***](#cite_ref-ASCII-1963_8-0) [***b***](#cite_ref-ASCII-1963_8-1) [***c***](#cite_ref-ASCII-1963_8-2) [***d***](#cite_ref-ASCII-1963_8-3) ["American Standard Code for Information Interchange, ASA X3.4-1963"](https://www.sensitiveresearch.com/Archive/CharCodeHist/X3.4-1963/index.html). *Sensitive Research*. [American Standards Association](/source/American_Standards_Association). 1963-06-17. Retrieved 2020-06-06.

1. ^ [***a***](#cite_ref-ASCII-1967_9-0) [***b***](#cite_ref-ASCII-1967_9-1) [***c***](#cite_ref-ASCII-1967_9-2) *USA Standard Code for Information Interchange, USAS X3.4-1967* (Technical report). [United States of America Standards Institute](/source/United_States_of_America_Standards_Institute). 1967-07-07.

1. **[^](#cite_ref-Jennings_2016_10-0)** [Jennings, Thomas Daniel](/source/Thomas_Daniel_Jennings) (2016-04-20) [1999]. ["An annotated history of some character codes or ASCII: American Standard Code for Information Infiltration"](https://www.sensitiveresearch.com/Archive/CharCodeHist/index.html#ASCII-1967). *Sensitive Research*. Retrieved 2020-03-08.

1. ^ [***a***](#cite_ref-ASCII-1986_11-0) [***b***](#cite_ref-ASCII-1986_11-1) [***c***](#cite_ref-ASCII-1986_11-2) [***d***](#cite_ref-ASCII-1986_11-3) *American National Standard for Information Systems — Coded Character Sets — 7-Bit American National Standard Code for Information Interchange (7-Bit ASCII), ANSI X3.4-1986* (Technical report). [American National Standards Institute](/source/American_National_Standards_Institute) (ANSI). 1986-03-26.

1. **[^](#cite_ref-Bukstein_1964_12-0)** Bukstein, Ed (July 1964). ["Binary Computer Codes and ASCII"](https://web.archive.org/web/20160303180933/http://www.swtpc.com/mholley/ElectronicsWorld/Jul1964/EW_Jul1964.htm). *[Electronics World](/source/Electronics_World)*. **72** (1): 28–29. Archived from [the original](http://www.swtpc.com/mholley/ElectronicsWorld/Jul1964/EW_Jul1964.htm) on 2016-03-03. Retrieved 2016-05-22.

1. ^ [***a***](#cite_ref-Bemer_1980_Inside_13-0) [***b***](#cite_ref-Bemer_1980_Inside_13-1) [***c***](#cite_ref-Bemer_1980_Inside_13-2) [***d***](#cite_ref-Bemer_1980_Inside_13-3) [***e***](#cite_ref-Bemer_1980_Inside_13-4) [***f***](#cite_ref-Bemer_1980_Inside_13-5) [Bemer, Robert William](/source/Robert_William_Bemer) (1980). ["Chapter 1: Inside ASCII"](https://web.archive.org/web/20160827000956/http://dlx.bookzz.org/genesis/772000/c80a62495acf1e1a5b966de23c1f989a/_as/%5BInterface_Age_Staff%5D_Best_of_Interface_Age%2C_Volum%28BookZZ.org%29.pdf) (PDF). *General Purpose Software*. Best of Interface Age. Vol. 2. Portland, OR, US: dilithium Press. pp. 1–50. [ISBN](/source/ISBN_(identifier)) [978-0-918398-37-6](https://en.wikipedia.org/wiki/Special:BookSources/978-0-918398-37-6). [LCCN](/source/LCCN_(identifier)) [79-67462](https://lccn.loc.gov/79-67462). Archived from [the original](http://bookzz.org/dl/1210234/1105c6) on 2016-08-27. Retrieved 2016-08-27, from: - [Bemer, Robert William](/source/Robert_William_Bemer) (May 1978). "Inside ASCII – Part I". *Interface Age*. **3** (5): 96–102. - [Bemer, Robert William](/source/Robert_William_Bemer) (June 1978). "Inside ASCII – Part II". *Interface Age*. **3** (6): 64–74. - [Bemer, Robert William](/source/Robert_William_Bemer) (July 1978). "Inside ASCII – Part III". *Interface Age*. **3** (7): 80–87.

1. **[^](#cite_ref-CCITT_1963_15-0)** Brief Report: Meeting of CCITT Working Party on the New Telegraph Alphabet, May 13–15, 1963.

1. **[^](#cite_ref-ISO_1963_16-0)** Report of ISO/TC/97/SC 2 – Meeting of October 29–31, 1963.

1. **[^](#cite_ref-17)** Report on Task Group X3.2.4, June 11, 1963, Pentagon Building, Washington, DC.

1. **[^](#cite_ref-18)** Report of Meeting No. 8, Task Group X3.2.4, December 17 and 18, 1963

1. ^ [***a***](#cite_ref-Winter_2010_19-0) [***b***](#cite_ref-Winter_2010_19-1) [***c***](#cite_ref-Winter_2010_19-2) Winter, Dik T. (2010) [2003]. ["US and International standards: ASCII"](https://web.archive.org/web/20100116001012/http://homepages.cwi.nl/~dik/english/codes/stand.html#ascii). Archived from [the original](http://homepages.cwi.nl/~dik/english/codes/stand.html#ascii) on 2010-01-16.

1. ^ [***a***](#cite_ref-ASCII-1968_20-0) [***b***](#cite_ref-ASCII-1968_20-1) [*USA Standard Code for Information Interchange, USAS X3.4-1968*](https://archive.org/details/enf-ascii-1968-1970/) (Technical report). [United States of America Standards Institute](/source/United_States_of_America_Standards_Institute). 1968-10-10.

1. ^ [***a***](#cite_ref-Salste_2016_21-0) [***b***](#cite_ref-Salste_2016_21-1) [***c***](#cite_ref-Salste_2016_21-2) [***d***](#cite_ref-Salste_2016_21-3) [***e***](#cite_ref-Salste_2016_21-4) [***f***](#cite_ref-Salste_2016_21-5) [***g***](#cite_ref-Salste_2016_21-6) Salste, Tuomas (January 2016). ["7-bit character sets: Revisions of ASCII"](http://www.aivosto.com/vbtips/charsets-7bit.html#body). Aivosto Oy. [urn](/source/URN_(identifier)):[nbn:fi-fe201201011004](https://nbn-resolving.de/urn:nbn:fi-fe201201011004). [Archived](https://web.archive.org/web/20160613145224/http://www.aivosto.com/vbtips/charsets-7bit.html#body) from the original on 2016-06-13. Retrieved 2016-06-13.

1. ^ [***a***](#cite_ref-RFC-20_1968_22-0) [***b***](#cite_ref-RFC-20_1968_22-1) [Cerf, Vint](/source/Vint_Cerf) (1969-10-16). [*ASCII format for Network Interchange*](https://www.rfc-editor.org/rfc/rfc20). Network Working Group. [doi](/source/Doi_(identifier)):[10.17487/RFC0020](https://doi.org/10.17487%2FRFC0020). [RFC](/source/Request_for_Comments) [20](https://datatracker.ietf.org/doc/html/rfc20). Retrieved 2016-06-13. (NB. Almost identical wording to [USAS X3.4-1968](/source/USAS_X3.4-1968) except for the intro.)

1. **[^](#cite_ref-23)** Barry Leiba (2015-01-12). ["Correct classification of RFC 20 (ASCII format) to Internet Standard"](https://datatracker.ietf.org/doc/status-change-rfc20-ascii-format-to-standard/). [IETF](/source/Internet_Engineering_Task_Force).

1. **[^](#cite_ref-SA_215_24-0)** "Information". *[Scientific American](/source/Scientific_American)* (special edition). **215** (3). September 1966. [JSTOR](/source/JSTOR_(identifier)) [e24931041](https://www.jstor.org/stable/e24931041).

1. **[^](#cite_ref-Korpela_2014_25-0)** Korpela, Jukka K. (2014-03-14) [2006-06-07]. *Unicode Explained – Internationalize Documents, Programs, and Web Sites* (2nd release of 1st ed.). [O'Reilly Media, Inc.](/source/O'Reilly_Media%2C_Inc.) p. 118. [ISBN](/source/ISBN_(identifier)) [978-0-596-10121-3](https://en.wikipedia.org/wiki/Special:BookSources/978-0-596-10121-3).

1. **[^](#cite_ref-ANSI_INCITS_4-1986_2007_26-0)** *ANSI INCITS 4-1986 (R2007): American National Standard for Information Systems – Coded Character Sets – 7-Bit American National Standard Code for Information Interchange (7-Bit ASCII)*, 2007 [1986]

1. **[^](#cite_ref-INCITS_4-1986_R2012_27-0)** ["INCITS 4-1986\[R2012\]: Information Systems - Coded Character Sets - 7-Bit American National Standard Code for Information Interchange (7-Bit ASCII)"](https://standards.incits.org/apps/group_public/project/details.php?project_id=796). 2012-06-15. [Archived](https://web.archive.org/web/20200228222040/https://standards.incits.org/apps/group_public/project/details.php?project_id=796) from the original on 2020-02-28. Retrieved 2020-02-28.

1. **[^](#cite_ref-INCITS_4-1986_R2017_28-0)** ["INCITS 4-1986\[R2017\]: Information Systems - Coded Character Sets - 7-Bit American National Standard Code for Information Interchange (7-Bit ASCII)"](https://standards.incits.org/apps/group_public/project/details.php?project_id=1829). 2017-11-02 [2017-06-09]. [Archived](https://web.archive.org/web/20200228221645/https://standards.incits.org/apps/group_public/project/details.php?project_id=1829) from the original on 2020-02-28. Retrieved 2020-02-28.

1. **[^](#cite_ref-29)** ["INCITS 4-1986 (R2022)"](https://webstore.ansi.org/standards/incits/incits1986r2022). *webstore.ansi.org*.

1. **[^](#cite_ref-X3.15-1966_30-0)** *Bit Sequencing of the American National Standard Code for Information Interchange in Serial-by-Bit Data Transmission*, [American National Standards Institute](/source/American_National_Standards_Institute) (ANSI), 1966, X3.15-1966

1. **[^](#cite_ref-31)** ["Telegraph Regulations and Final Protocol (Madrid, 1932)"](https://web.archive.org/web/20230821020920/https://search.itu.int/history/HistoryDigitalCollectionDocLibrary/4.5.43.en.101.pdf) (PDF). Archived from [the original](http://handle.itu.int/11.1004/020.1000/4.5.43.en.101) on 2023-08-21. Retrieved 2024-06-09.

1. ^ [***a***](#cite_ref-bdcode_32-0) [***b***](#cite_ref-bdcode_32-1) Smith, Gil (2001). ["Teletype Communication Codes"](http://www.baudot.net/docs/smith--teletype-codes.pdf) (PDF). Baudot.net. [Archived](https://web.archive.org/web/20080820043949/http://www.baudot.net/docs/smith--teletype-codes.pdf) (PDF) from the original on 2008-08-20. Retrieved 2008-07-11.

1. **[^](#cite_ref-Sawyer_1995_33-0)** Sawyer, Stanley A.; Krantz, Steven George (1995). [*A TeX Primer for Scientists*](https://books.google.com/books?id=bXLDwmIJNkUC&pg=PA13). [CRC Press](/source/CRC_Press). p. 13. [Bibcode](/source/Bibcode_(identifier)):[1995tps..book.....S](https://ui.adsabs.harvard.edu/abs/1995tps..book.....S). [ISBN](/source/ISBN_(identifier)) [978-0-8493-7159-2](https://en.wikipedia.org/wiki/Special:BookSources/978-0-8493-7159-2). [Archived](https://web.archive.org/web/20161222151907/https://books.google.com/books?id=bXLDwmIJNkUC&pg=PA13) from the original on 2016-12-22. Retrieved 2016-10-29.

1. **[^](#cite_ref-Savard_34-0)** Savard, John J. G. ["Computer Keyboards"](http://www.quadibloc.com/comp/kybint.htm). [Archived](https://web.archive.org/web/20140924183236/http://www.quadibloc.com/comp/kybint.htm) from the original on 2014-09-24. Retrieved 2014-08-24.

1. **[^](#cite_ref-35)** ["ASCIIbetical definition"](https://web.archive.org/web/20130309183509/http://www.pcmag.com/encyclopedia_term/0%2C2542%2Ct%3DASCIIbetical%26i%3D38025%2C00.asp). *[PC Magazine](/source/PC_Magazine)*. Archived from [the original](https://www.pcmag.com/encyclopedia_term/0,2542,t=ASCIIbetical&i=38025,00.asp) on 2013-03-09. Retrieved 2008-04-14.

1. **[^](#cite_ref-RFC-2822_36-0)** Resnick, Peter W., ed. (April 2001). [*Internet Message Format*](https://www.rfc-editor.org/rfc/rfc2822). [IETF](/source/Internet_Engineering_Task_Force). [doi](/source/Doi_(identifier)):[10.17487/RFC2822](https://doi.org/10.17487%2FRFC2822). [RFC](/source/Request_for_Comments) [2822](https://datatracker.ietf.org/doc/html/rfc2822). Retrieved 2016-06-13. (NB. NO-WS-CTL.)

1. **[^](#cite_ref-McConnell_37-0)** McConnell, Robert; Haynes, James; Warren, Richard. ["Understanding ASCII Codes"](https://web.archive.org/web/20140227190425/http://www.nadcomm.com/ascii_code.htm). Archived from [the original](http://www.nadcomm.com/ascii_code.htm) on 2014-02-27. Retrieved 2014-05-11.

1. **[^](#cite_ref-38)** Barry Margolin (2014-05-29). ["Re: editor and word processor history (was: Re: RTF for emacs)"](http://lists.gnu.org/archive/html/help-gnu-emacs/2014-05/msg00448.html). *help-gnu-emacs* (Mailing list). [Archived](https://web.archive.org/web/20140714133149/http://lists.gnu.org/archive/html/help-gnu-emacs/2014-05/msg00448.html) from the original on 2014-07-14. Retrieved 2014-07-11.

1. ^ [***a***](#cite_ref-pdp-6-monitor-manual_39-0) [***b***](#cite_ref-pdp-6-monitor-manual_39-1) ["PDP-6 Multiprogramming System Manual"](http://bitsavers.trailing-edge.com/pdf/dec/pdp6/DEC-6-0-EX-SYS-UM-IP-PRE00_Multiprogramming_System_Manual_1965.pdf) (PDF). [Digital Equipment Corporation](/source/Digital_Equipment_Corporation) (DEC). 1965. p. 43. [Archived](https://web.archive.org/web/20140714140253/http://bitsavers.trailing-edge.com/pdf/dec/pdp6/DEC-6-0-EX-SYS-UM-IP-PRE00_Multiprogramming_System_Manual_1965.pdf) (PDF) from the original on 2014-07-14. Retrieved 2014-07-10.

1. ^ [***a***](#cite_ref-pdp-10-monitor-manual_40-0) [***b***](#cite_ref-pdp-10-monitor-manual_40-1) ["PDP-10 Reference Handbook, Book 3, Communicating with the Monitor"](http://bitsavers.org/pdf/dec/pdp10/1970_PDP-10_Ref/1970PDP10Ref_Part3.pdf) (PDF). [Digital Equipment Corporation](/source/Digital_Equipment_Corporation) (DEC). 1969. p. 5-5. [Archived](https://web.archive.org/web/20111115083418/http://www.bitsavers.org/pdf/dec/pdp10/1970_PDP-10_Ref/1970PDP10Ref_Part3.pdf) (PDF) from the original on 2011-11-15. Retrieved 2014-07-10.

1. **[^](#cite_ref-41)** ["Help - GNU Emacs Manual"](https://www.gnu.org/software/emacs/manual/html_node/emacs/Help.html). [Archived](https://web.archive.org/web/20180711223750/https://www.gnu.org/software/emacs/manual/html_node/emacs/Help.html) from the original on 2018-07-11. Retrieved 2018-07-11.

1. **[^](#cite_ref-42)** ["ANSI X3.64-1979"](https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub86.pdf) (PDF). Retrieved 2024-10-27.

1. **[^](#cite_ref-43)** [Tim Paterson](/source/Tim_Paterson) (2007-08-08). ["Is DOS a Rip-Off of CP/M?"](http://dosmandrivel.blogspot.com/2007/08/is-dos-rip-off-of-cpm.html). *DosMan Drivel*. [Archived](https://web.archive.org/web/20180420075137/http://dosmandrivel.blogspot.com/2007/08/is-dos-rip-off-of-cpm.html) from the original on 2018-04-20. Retrieved 2018-04-19.

1. **[^](#cite_ref-44)** [Ossanna, J. F.](/source/Joe_Ossanna); [Saltzer, J. H.](/source/Jerry_Saltzer) (November 17–19, 1970). ["Technical and human engineering problems in connecting terminals to a time-sharing system"](http://www.multicians.org/jhs-jfo-terminals.pdf) (PDF). *Proceedings of the November 17–19, 1970, [Fall Joint Computer Conference](/source/Fall_Joint_Computer_Conference) (FJCC)*. [AFIPS](/source/AFIPS) Press. pp. 355–362. [Archived](https://web.archive.org/web/20120819085101/http://www.multicians.org/jhs-jfo-terminals.pdf) (PDF) from the original on 2012-08-19. Retrieved 2013-01-29. Using a "new-line" function (combined carriage-return and line-feed) is simpler for both man and machine than requiring both functions for starting a new line; the American National Standard X3.4-1968 permits the line-feed code to carry the new-line meaning.

1. **[^](#cite_ref-RFC-158_45-0)** O'Sullivan, T. (1971-05-19). [*TELNET Protocol*](https://www.rfc-editor.org/rfc/rfc158). [Internet Engineering Task Force](/source/Internet_Engineering_Task_Force) (IETF). pp. 4–5. [doi](/source/Doi_(identifier)):[10.17487/RFC0158](https://doi.org/10.17487%2FRFC0158). [RFC](/source/Request_for_Comments) [158](https://datatracker.ietf.org/doc/html/rfc158). Retrieved 2013-01-28.

1. **[^](#cite_ref-RFC-542_46-0)** Neigus, Nancy J. (1973-08-12). [*File Transfer Protocol*](https://www.rfc-editor.org/rfc/rfc542). [Internet Engineering Task Force](/source/Internet_Engineering_Task_Force) (IETF). [doi](/source/Doi_(identifier)):[10.17487/RFC0542](https://doi.org/10.17487%2FRFC0542). [RFC](/source/Request_for_Comments) [542](https://datatracker.ietf.org/doc/html/rfc542). Retrieved 2013-01-28.

1. **[^](#cite_ref-RFC-765_47-0)** [Postel, Jon](/source/Jon_Postel) (June 1980). [*File Transfer Protocol*](https://www.rfc-editor.org/rfc/rfc765). [Internet Engineering Task Force](/source/Internet_Engineering_Task_Force) (IETF). [doi](/source/Doi_(identifier)):[10.17487/RFC0765](https://doi.org/10.17487%2FRFC0765). [RFC](/source/Request_for_Comments) [765](https://datatracker.ietf.org/doc/html/rfc765). Retrieved 2013-01-28.

1. **[^](#cite_ref-RFC-822_48-0)** Crocker, David (1982-08-13). [*STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGES*](https://www.rfc-editor.org/rfc/rfc822). [Internet Engineering Task Force](/source/Internet_Engineering_Task_Force) (IETF). [doi](/source/Doi_(identifier)):[10.17487/RFC0822](https://doi.org/10.17487%2FRFC0822). [RFC](/source/Request_for_Comments) [822](https://datatracker.ietf.org/doc/html/rfc822).

1. **[^](#cite_ref-RFC-1945_49-0)** Berners-Lee, Tim; et al. (May 1996). [*Hypertext Transfer Protocol -- HTTP/1.0*](https://www.rfc-editor.org/rfc/rfc1945). [Internet Engineering Task Force](/source/Internet_Engineering_Task_Force) (IETF). [doi](/source/Doi_(identifier)):[10.17487/RFC1945](https://doi.org/10.17487%2FRFC1945). [RFC](/source/Request_for_Comments) [1945](https://datatracker.ietf.org/doc/html/rfc1945).

1. **[^](#cite_ref-50)** ["EOL translation plan for Mercurial"](https://www.mercurial-scm.org/wiki/EOLTranslationPlan). Mercurial. [Archived](https://web.archive.org/web/20160616235536/https://www.mercurial-scm.org/wiki/EOLTranslationPlan) from the original on 2016-06-16. Retrieved 2017-06-24.

1. **[^](#cite_ref-51)** [Bernstein, Daniel J.](/source/Daniel_J._Bernstein) ["Bare LFs in SMTP"](http://cr.yp.to/docs/smtplf.html). [Archived](https://web.archive.org/web/20111029013105/http://cr.yp.to/docs/smtplf.html) from the original on 2011-10-29. Retrieved 2013-01-28.

1. **[^](#cite_ref-52)** [*CP/M 1.4 Interface Guide*](http://www.bitsavers.org/pdf/digitalResearch/cpm/1.4/CPM_1.4_Interface_Guide_1978.pdf) (PDF). [Digital Research](/source/Digital_Research). 1978. p. 10. [Archived](https://web.archive.org/web/20190529055800/http://bitsavers.org/pdf/digitalResearch/cpm/1.4/CPM_1.4_Interface_Guide_1978.pdf) (PDF) from the original on 2019-05-29. Retrieved 2017-10-07.

1. **[^](#cite_ref-Haynes_2015_66-0)** Haynes, Jim (2015-01-13). ["First-Hand: Chad is Our Most Important Product: An Engineer's Memory of Teletype Corporation"](https://ethw.org/First-Hand:Chad_is_Our_Most_Important_Product:_An_Engineer's_Memory_of_Teletype_Corporation). Engineering and Technology History Wiki (ETHW). Retrieved 2023-02-14. There was the change from 1961 ASCII to 1968 ASCII. Some computer languages used characters in 1961 ASCII such as up arrow and left arrow. These characters disappeared from 1968 ASCII. We worked with Fred Mocking, who by now was in Sales at [Teletype](/source/Teletype_Corporation), on a type cylinder that would compromise the changing characters so that the meanings of 1961 ASCII were not totally lost. The underscore character was made rather wedge-shaped so it could also serve as a left arrow.

1. **[^](#cite_ref-67)** [Bemer, Robert William](/source/Robert_William_Bemer). ["Bemer meets Europe (Computer Standards) – Computer History Vignettes"](https://web.archive.org/web/20131017062722/http://www.trailing-edge.com/~bobbemer/EUROPE.HTM). Trailing-edge.com. Archived from [the original](http://www.trailing-edge.com/~bobbemer/EUROPE.HTM) on 2013-10-17. Retrieved 2008-04-14. (NB. Bemer was employed at [IBM](/source/IBM) at that time.)

1. **[^](#cite_ref-thocp_68-0)** ["Robert William Bemer: Biography"](http://www.thocp.net/biographies/bemer_bob.htm). 2013-03-09. [Archived](https://web.archive.org/web/20160616081929/http://www.thocp.net/biographies/bemer_bob.htm) from the original on 2016-06-16.

1. **[^](#cite_ref-Johnson_1968_69-0)** [Johnson, Lyndon Baines](/source/Lyndon_Baines_Johnson) (1968-03-11). ["Memorandum Approving the Adoption by the Federal Government of a Standard Code for Information Interchange"](http://www.presidency.ucsb.edu/ws/index.php?pid=28724). The American Presidency Project. [Archived](https://web.archive.org/web/20070914121230/http://www.presidency.ucsb.edu/ws/index.php?pid=28724) from the original on 2007-09-14. Retrieved 2008-04-14.

1. **[^](#cite_ref-70)** Richard S. Shuford (1996-12-20). ["Re: Early history of ASCII?"](https://groups.google.com/d/msg/alt.folklore.computers/gbg5YVFaT48/wlVFfJ2j4hYJ). [Newsgroup](/source/Usenet_newsgroup): [alt.folklore.computers](news:alt.folklore.computers). [Usenet:](/source/Usenet_(identifier)) [Pine.SUN.3.91.961220100220.13180C-100000@duncan.cs.utk.edu](news:Pine.SUN.3.91.961220100220.13180C-100000@duncan.cs.utk.edu).

1. **[^](#cite_ref-Folts_1982_71-0)** Folts, Harold C.; Karp, Harry, eds. (1982-02-01). *Compilation of Data Communications Standards* (2nd revised ed.). [McGraw-Hill Inc.](/source/McGraw-Hill_Inc.) [ISBN](/source/ISBN_(identifier)) [978-0-07-021457-6](https://en.wikipedia.org/wiki/Special:BookSources/978-0-07-021457-6).

1. **[^](#cite_ref-Dubost_2008_72-0)** Dubost, Karl (2008-05-06). ["UTF-8 Growth on the Web"](http://www.w3.org/QA/2008/05/utf8-web-growth.html). *W3C Blog*. [World Wide Web Consortium](/source/World_Wide_Web_Consortium). [Archived](https://web.archive.org/web/20160616084132/https://www.w3.org/blog/2008/05/utf8-web-growth/) from the original on 2016-06-16. Retrieved 2010-08-15.

1. ^ [***a***](#cite_ref-UTF-8_2008_73-0) [***b***](#cite_ref-UTF-8_2008_73-1) [Davis, Mark](/source/Mark_Davis_(Unicode)) (2008-05-05). ["Moving to Unicode 5.1"](http://googleblog.blogspot.com/2008/05/moving-to-unicode-51.html). *Official Google Blog*. [Archived](https://web.archive.org/web/20160616084637/https://googleblog.blogspot.de/2008/05/moving-to-unicode-51.html) from the original on 2016-06-16. Retrieved 2010-08-15.

1. **[^](#cite_ref-Davis_2010_74-0)** [Davis, Mark](/source/Mark_Davis_(Unicode)) (2010-01-28). ["Unicode nearing 50% of the web"](http://googleblog.blogspot.com/2010/01/unicode-nearing-50-of-web.html). *Official Google Blog*. [Archived](https://web.archive.org/web/20160616085323/https://googleblog.blogspot.de/2010/01/unicode-nearing-50-of-web.html) from the original on 2016-06-16. Retrieved 2010-08-15.

1. **[^](#cite_ref-75)** "Specific Criteria", attachment to memo from R. W. Reach, "X3-2 Meeting – September 14 and 15", September 18, 1961

1. **[^](#cite_ref-Maréchal_1967_76-0)** Maréchal, R. (1967-12-22), *ISO/TC 97 – Computers and Information Processing: Acceptance of Draft ISO Recommendation No. 1052*

1. **[^](#cite_ref-77)** ["DVB-TXT (Teletext) Specification for conveying ITU-R System B Teletext in DVB bitstreams"](https://dvb.org/?standard=specification-for-conveying-itu-r-system-b-teletext-in-dvb-bitstreams).

1. **[^](#cite_ref-78)** [*Technical Reference*](http://www.bitsavers.org/pdf/ibm/pc/pc/6025008_PC_Technical_Reference_Aug81.pdf) (PDF). Personal Computer Hardware Reference Library (First ed.). IBM. August 1981. Appendix C. Of Characters Keystrokes and Color.

1. **[^](#cite_ref-Unicode-5.0_2006_79-0)** The Unicode Consortium (2006-10-27). ["Chapter 13: Special Areas and Format Characters"](http://unicode.org/book/ch13.pdf) (PDF). In Allen, Julie D. (ed.). *The Unicode standard, Version 5.0*. Upper Saddle River, New Jersey, US: [Addison-Wesley Professional](/source/Addison-Wesley_Professional). p. 314. [ISBN](/source/ISBN_(identifier)) [978-0-321-48091-0](https://en.wikipedia.org/wiki/Special:BookSources/978-0-321-48091-0). [Archived](https://ghostarchive.org/archive/20221009/http://unicode.org/book/ch13.pdf) (PDF) from the original on 2022-10-09. Retrieved 2015-03-13.

1. **[^](#cite_ref-80)** ["utf-8(7) – Linux manual page"](http://man7.org/linux/man-pages/man7/utf-8.7.html). Man7.org. 2014-02-26. [Archived](https://web.archive.org/web/20140422232059/http://man7.org/linux/man-pages/man7/utf-8.7.html) from the original on 2014-04-22. Retrieved 2014-04-21.

## Further reading

- [Bemer, Robert William](/source/Robert_William_Bemer) (1960). ["A Proposal for Character Code Compatibility"](https://doi.org/10.1145%2F366959.366961). *Communications of the ACM*. **3** (2): 71–72. [doi](/source/Doi_(identifier)):[10.1145/366959.366961](https://doi.org/10.1145%2F366959.366961). [S2CID](/source/S2CID_(identifier)) [9591147](https://api.semanticscholar.org/CorpusID:9591147).

- [Bemer, Robert William](/source/Robert_William_Bemer) (2003-05-23). ["The Babel of Codes Prior to ASCII: The 1960 Survey of Coded Character Sets: The Reasons for ASCII"](https://web.archive.org/web/20131017062654/http://www.trailing-edge.com/~bobbemer/SURVEY.HTM). Archived from [the original](http://www.trailing-edge.com/~bobbemer/SURVEY.HTM) on 2013-10-17. Retrieved 2016-05-09, from: - [Bemer, Robert William](/source/Robert_William_Bemer) (December 1960). ["Survey of coded character representation"](https://doi.org/10.1145%2F367487.367493). *[Communications of the ACM](/source/Communications_of_the_ACM)*. **3** (12): 639–641. [doi](/source/Doi_(identifier)):[10.1145/367487.367493](https://doi.org/10.1145%2F367487.367493). [S2CID](/source/S2CID_(identifier)) [21403172](https://api.semanticscholar.org/CorpusID:21403172). - Smith, H. J.; Williams, F. A. (December 1960). ["Survey of punched card codes"](https://doi.org/10.1145%2F367487.367491). *[Communications of the ACM](/source/Communications_of_the_ACM)*. **3** (12): 642. [doi](/source/Doi_(identifier)):[10.1145/367487.367491](https://doi.org/10.1145%2F367487.367491).

- ["American National Standard Code for Information Interchange | ANSI X3.4-1977"](https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub1-2-1977.pdf) (PDF). National Institute for Standards. 1977. [Archived](https://ghostarchive.org/archive/20221009/https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub1-2-1977.pdf) (PDF) from the original on 2022-10-09. (facsimile, not machine readable)

- Robinson, G. S.; Cargill, C. (1996). "History and impact of computer standards". *[Computer](/source/Computer_(magazine))*. Vol. 29, no. 10. pp. 79–85. [doi](/source/Doi_(identifier)):[10.1109/2.539725](https://doi.org/10.1109%2F2.539725).

- Mullendore, Ralph Elvin (1964) [1963]. Ptak, John F. (ed.). ["On the Early Development of ASCII – The History of ASCII"](http://longstreet.typepad.com/thesciencebookstore/2012/03/heres-the-link.html). JF Ptak Science Books (published March 2012). [Archived](https://web.archive.org/web/20160526181319/http://longstreet.typepad.com/thesciencebookstore/2012/03/heres-the-link.html) from the original on 2016-05-26. Retrieved 2016-05-26.

## External links

Wikimedia Commons has media related to [ASCII](https://commons.wikimedia.org/wiki/Category:ASCII).

- ["C0 Controls and Basic Latin – Range: 0000–007F"](https://www.unicode.org/charts/PDF/U0000.pdf) (PDF). *The Unicode Standard 8.0*. [Unicode, Inc.](/source/Unicode%2C_Inc.) 2015 [1991]. [Archived](https://web.archive.org/web/20160526182105/http://www.unicode.org/charts/PDF/U0000.pdf) (PDF) from the original on 2016-05-26. Retrieved 2016-05-26.

v t e Character encodings Early telecommunication Telegraph code Needle Morse Non-Latin Wabun/Kana Chinese Cyrillic Baudot and Murray Fieldata ASCII ISO/IEC 646 BCDIC Teletex and Videotex/Teletext T.51/ISO/IEC 6937 ITU T.61 ITU T.101 World System Teletext background sets Transcode ISO/IEC 8859 Approved parts -1 (Western Europe) -2 (Central Europe) -3 (Maltese/Esperanto) -4 (North Europe) -5 (Cyrillic) -6 (Arabic) -7 (Greek) -8 (Hebrew) -9 (Turkish) -10 (Nordic) -11 (Thai) -13 (Baltic) -14 (Celtic) -15 (New Western Europe) -16 (Romanian) Abandoned parts -12 (Devanagari) Proposed but not approved KOI-8 Cyrillic Sámi Adaptations Welsh Estonian Ukrainian Cyrillic Bibliographic use MARC-8 ANSEL CCCII/EACC ISO 5426 5426-2 5427 5428 6438 6862 National standards ArmSCII Big5 BraSCII BSCII CNS 11643 DIN 66003 ELOT 927 GOST 10859 GB 2312 GB 12345 GB 12052 GB 18030 HKSCS ISCII JIS X 0201 JIS X 0208 JIS X 0212 JIS X 0213 KOI-7 KPS 9566 KS X 1001 KS X 1002 LST 1564 LST 1590-4 PASCII Shift JIS SI 960 TIS-620 TSCII VISCII VSCII YUSCII ISO/IEC 2022 ISO/IEC 8859 ISO/IEC 10367 Extended Unix Code (EUC) Code pages Mac OS ("scripts") Armenian Arabic Barents Cyrillic Celtic Central European Croatian Cyrillic Devanagari Font X (Kermit) Gaelic Georgian Greek Gujarati Gurmukhi Hebrew Iceland Inuit Keyboard Latin (Kermit) Maltese/Esperanto Ogham Roman Romanian Sámi Turkish Turkic Cyrillic Ukrainian VT100 DOS 437 737 850 858 861 862 863 864 865 866 867 868 869 899 904 932 936 942 949 950 951 1040 1043 1046 1098 1115 1116 1117 1118 1127 ABICOMP CS Indic CSX Indic CSX+ Indic CWI-2 Iran System Kamenický Mazovia MIK IBM AIX 895 896 912 915 921 922 1006 1008 1009 1010 1012 1013 1014 1015 1016 1017 1018 1019 1046 1133 Windows CER-GS 932 936 (GBK) 950 Extended Latin-8 1250 1251 1252 1253 1254 1255 1256 1257 1258 1270 Cyrillic + French Cyrillic + German Polytonic Greek EBCDIC Japanese language in EBCDIC DKOI DEC terminals (VTx) Multinational (MCS) National Replacement (NRCS) French Canadian Swiss Spanish United Kingdom Dutch Finnish French Norwegian and Danish Swedish Norwegian and Danish (alternative) 8-bit Greek 8-bit Turkish SI 960 Hebrew Special Graphics Technical (TCS) Platform specific 1052 1053 1054 1055 1058 Acorn RISC OS Amstrad CPC Apple II ATASCII Atari ST BICS Casio calculators CDC Compucolor 8001 Compucolor II CP/M+ DEC RADIX 50 DEC MCS/NRCS DG International Galaksija GEM GSM 03.38 HP Roman HP FOCAL HP RPL SQUOZE LICS LMBCS MSX NEC APC NeXT PETSCII PostScript Standard PostScript Latin 1 SAM Coupé Sega SC-3000 Sharp calculators Sharp MZ Sinclair QL Teletext TI calculators TRS-80 Ventura International WISCII XCCS ZX80 ZX81 ZX Spectrum Other ABICOMP ASMO 449 Digital encoding of APL symbols ISO-IR-68 ARIB STD-B24 Fieldata HZ IEC-P27-1 INIS 7-bit 8-bit ISO-IR-169 ISO 2033 KOI KOI8-R KOI8-RU KOI8-U Mojikyō SEASCII Stanford/ITS Symbol TRON Unified Hangul Code Unicode, ISO/IEC 10646 UTF-1 UTF-7 UTF-8 UTF-16 UTF-32 UTF-EBCDIC GB 18030 DIN 91379 BOCU-1 CESU-8 SCSU TACE16 Comparison of Unicode encodings TeX typesetting Cork LY1 OML OMS OT1 Control character Morse prosigns C0 and C1 control codes ISO/IEC 6429 JIS X 0211 Unicode control, format and separator characters Whitespace characters Related topics CCSID Character encodings in HTML Charset detection Han unification Hardware code page MICR code Mojibake Variable-length encoding Character sets

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Adapted from the Wikipedia article [ASCII](https://en.wikipedia.org/wiki/ASCII) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/ASCII?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.