A
compose key, available on some
computer keyboardIn computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
s, is a special kind of
modifier keyIn computing, a modifier key is a special key on a computer keyboard that modifies the normal action of another key when the two are pressed in combination....
designated to signal the software to interpret the following sequence of two (or more) keystrokes as a combination in order to produce a character not found directly on the keyboard. For example, striking followed by and then may produce the ligature
æ, whereas striking followed by and then can yield
© (circled
C, the
copyright symbolThe copyright symbol, or copyright sign, designated by © , is the symbol used in copyright notices for works other than sound recordings . The use of the symbol is described in United States copyright law, and, internationally, by the Universal Copyright Convention...
).
The compose key can be found on the
LK201The LK201 was a detachable computer keyboard introduced by Digital Equipment Corporation of Maynard, Massachusetts in 1982. It was first used by Digital's VT220 ANSI/ASCII terminal and was subsequently used by the Rainbow-100, DECmate-II, and Pro-350 microcomputers and many of Digital's computer...
family of keyboards from
Digital Equipment CorporationDigital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
and its successors. The key can also be found on keyboards from
Sun MicrosystemsSun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
. However, any key on a keyboard can be configured to serve as a compose key, as long as the functionality is supported by the software in use.
Usage
The compose key is different from a typical modifier key (such as
A compose key, available on some computer keyboardIn computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
s, is a special kind of
modifier keyIn computing, a modifier key is a special key on a computer keyboard that modifies the normal action of another key when the two are pressed in combination....
designated to signal the software to interpret the following sequence of two (or more) keystrokes as a combination in order to produce a character not found directly on the keyboard. For example, striking {{key press|Compose}} followed by {{key press|A}} and then {{key press|E}} may produce the ligature
æ, whereas striking {{key press|Compose}} followed by {{key press|O}} and then {{key press|C}} can yield
© (circled
C, the
copyright symbolThe copyright symbol, or copyright sign, designated by © , is the symbol used in copyright notices for works other than sound recordings . The use of the symbol is described in United States copyright law, and, internationally, by the Universal Copyright Convention...
).
The compose key can be found on the
LK201The LK201 was a detachable computer keyboard introduced by Digital Equipment Corporation of Maynard, Massachusetts in 1982. It was first used by Digital's VT220 ANSI/ASCII terminal and was subsequently used by the Rainbow-100, DECmate-II, and Pro-350 microcomputers and many of Digital's computer...
family of keyboards from
Digital Equipment CorporationDigital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
and its successors. The key can also be found on keyboards from
Sun MicrosystemsSun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
. However, any key on a keyboard can be configured to serve as a compose key, as long as the functionality is supported by the software in use.
Usage
The compose key is different from a typical modifier key (such as
A compose key, available on some computer keyboardIn computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
s, is a special kind of
modifier keyIn computing, a modifier key is a special key on a computer keyboard that modifies the normal action of another key when the two are pressed in combination....
designated to signal the software to interpret the following sequence of two (or more) keystrokes as a combination in order to produce a character not found directly on the keyboard. For example, striking {{key press|Compose}} followed by {{key press|A}} and then {{key press|E}} may produce the ligature
æ, whereas striking {{key press|Compose}} followed by {{key press|O}} and then {{key press|C}} can yield
© (circled
C, the
copyright symbolThe copyright symbol, or copyright sign, designated by © , is the symbol used in copyright notices for works other than sound recordings . The use of the symbol is described in United States copyright law, and, internationally, by the Universal Copyright Convention...
).
The compose key can be found on the
LK201The LK201 was a detachable computer keyboard introduced by Digital Equipment Corporation of Maynard, Massachusetts in 1982. It was first used by Digital's VT220 ANSI/ASCII terminal and was subsequently used by the Rainbow-100, DECmate-II, and Pro-350 microcomputers and many of Digital's computer...
family of keyboards from
Digital Equipment CorporationDigital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
and its successors. The key can also be found on keyboards from
Sun MicrosystemsSun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
. However, any key on a keyboard can be configured to serve as a compose key, as long as the functionality is supported by the software in use.
Usage
The compose key is different from a typical modifier key (such as
{{key pressAltGr is a modifier key found on many computer keyboards and primarily used to type characters that are unusual for the locale of the keyboard layout, such as currency symbols and accented letters...
or
{{key pressThe Option key is a modifier key present on Apple keyboards. It is located between the Control key and Command key on a typical Mac keyboard. There are two option keys on modern Mac desktop and notebook keyboards, one on each side of the space bar....
) in that, rather than being pressed and held while another key is struck, it is
pressed and released before striking the keys to be modified. Typically, the text-entry system does not indicate that any keys have been pressed until the composed character appears after the final keystroke of a predefined sequence. Therefore, the compose key can also be described as a kind of generic
dead keyA dead key is a special kind of a modifier key on a typewriter or computer keyboard that is typically used to attach a specific diacritic to a base letter. The dead key does not generate a character by itself but modifies the character generated by the key struck immediately after...
. What makes the compose key different from a dead key is that while each dead key can only be used to attach a specific
diacriticA diacritic is a glyph added to a letter, or basic glyph. The term derives from the Greek διακριτικός . Diacritic is both an adjective and a noun, whereas diacritical is only an adjective. Some diacritical marks, such as the acute and grave are often called accents...
to various base letters, the compose key can be used to produce any kind of a character supported by the character set and
fontIn typography, a font is traditionally defined as a quantity of sorts composing a complete character set of a single size and style of a particular typeface...
in use. This way, an even wider variety of special characters can be made available on a keyboard with a limited number of keys.
In a loose sense, the character produced with a compose-key sequence can be seen as a
precomposed characterA precomposed character is a Unicode entity that can be defined as a combination of two or more other characters. A precomposed character may typically represent a letter with a diacritical mark, such as é...
, but it does not need to be technically decomposable or have any visual resemblance with the characters normally produced with the same keys (i.e., without striking the compose key first). Nevertheless, there is usually some kind of an association that helps to make the key sequence more mnemonic. For example, typing {{key press|Compose}} followed by {{key press|T}} and then {{key press|H}} may produce the Icelandic (as well as Old Norse and Old English) letter
þ (
thornThorn or þorn , is a letter in the Old English, Old Norse, and Icelandic alphabets, as well as some dialects of Middle English. It was also used in medieval Scandinavia, but was later replaced with the digraph th. The letter originated from the rune in the Elder Fuþark, called thorn in the...
), which
phoneticallyPhonetics is a branch of linguistics that comprises the study of the sounds of human speech, or—in the case of sign languages—the equivalent aspects of sign. It is concerned with the physical properties of speech sounds or signs : their physiological production, acoustic properties, auditory...
corresponds to the
digraphA digraph or digram is a pair of characters used to write one phoneme or a sequence of phonemes that does not correspond to the normal values of the two characters combined...
th in, e.g.,
thing.
Compose key in various computer systems
The compose key is known as "Multi_key" in the
X Window SystemThe X window system is a computer software system and network protocol that provides a basis for graphical user interfaces and rich input device capability for networked computers...
, and must be interpreted by the client program (typically Xlib), not the server. In
XFree86XFree86 is an implementation of the X Window System. It was originally written for Unix-like operating systems on IBM PC compatibles and is now available for many other operating systems and platforms. It is free and open source software under the XFree86 License version 1.1. It is developed by the...
and
X.Org ServerX.Org Server refers to the X server release packages stewarded by the X.Org Foundation,which is hosted by freedesktop.org, and grants...
, many keyboard layouts have a variant that maps Multi_key to some key, usually (on PC keyboards) to either of the
Windows keyThe Windows logo key—also known as the Windows key, the home key, the meta key, the start key, MOD4, or the flag key —is a keyboard key which was originally introduced on the Microsoft Natural keyboard before the release of Windows 95. This key became a standard key on PC keyboards...
s, or
{{key pressThe shift key is a modifier key on a keyboard, used to type capital letters and other alternate "upper" characters. There are typically two shift keys, on the left and right sides of the row below the home row...
+{{key press or sometimes {{key press|Shift|Right-Ctrl}}.{{Citation needed|date=July 2011}} It can also be specified in XkbOptions (for example, "compose:rwin"). Multi_key can also be assigned with the xmodmap(1) utility. Note that it is common for
{{key pressThe shift key is a modifier key on a keyboard, used to type capital letters and other alternate "upper" characters. There are typically two shift keys, on the left and right sides of the row below the home row...
+{{key press to be mapped to the compose key, but for {{key press+
{{key pressThe shift key is a modifier key on a keyboard, used to type capital letters and other alternate "upper" characters. There are typically two shift keys, on the left and right sides of the row below the home row...
to be mapped to the fourth "keyboard level" modifier. The first three levels correspond to holding no modifiers,
{{key pressThe shift key is a modifier key on a keyboard, used to type capital letters and other alternate "upper" characters. There are typically two shift keys, on the left and right sides of the row below the home row...
, and {{key press respectively. So for example the copyright symbol, © can be typed using the compose key as
{{key pressThe shift key is a modifier key on a keyboard, used to type capital letters and other alternate "upper" characters. There are typically two shift keys, on the left and right sides of the row below the home row...
+{{key press, {{key press|o}}, {{key press|c}}, or using the level four modifier as {{key press+
{{key pressThe shift key is a modifier key on a keyboard, used to type capital letters and other alternate "upper" characters. There are typically two shift keys, on the left and right sides of the row below the home row...
+{{key press|c}}.
ISO/IEC 9995ISO/IEC 9995 Information technology — Keyboard layouts for text and office systems is an ISO standard defining layouts of computer keyboards. It defines a keyboard as having three groups of key assignments:...
-7 assigned to this key a graphical symbol ⎄, which exists in Unicode as U+2384 since version 3.0.0 of the standard. However, this symbol doesn't appear to be used by the industry.
Originally the currency sign on the keyboards were nationalized,
and not every keyboard sold in the world contained a dollar sign ($),
which explains why it appears there{{Clarify|date=February 2009}},
although it is part of any standard{{By whom|date=May 2011}} keyboard since the 1990s.
In particular the $ compose sequence
ceased to work {{when|date=May 2011}} on modern {{Which?|date=May 2011}} systems.
The historic backslash sequence (compose-//) witnesses of the similar situation for this key
and is still working on modern systems.
Microsoft WindowsMicrosoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
does not use a compose key as such, but a few programs such as
PuTTYPuTTY is a free and open source terminal emulator application which can act as a client for the SSH, Telnet, rlogin, and raw TCP computing protocols and as a serial console client...
provide compose key support. There are also a number of
open sourceThe term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
utilitiesIn economics, utility is a measure of customer satisfaction, referring to the total satisfaction received by a consumer from consuming a good or service....
(such as
AllChars) and installable keyboard layouts available that emulate the compose key using a selectable modifier key like Control or AltGr.
Common compose combinations
The table shown below contains the current common compositions for Xorg 7. Other compositions may work, based on the de-facto
SunSun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
/
DECDigital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
/Falco standard. Particularly for modern systems which support customizable compose sequences and
UnicodeUnicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
, the table would be far from complete. Given the vast number of sequences permissible and the vast number of characters available in Unicode, a complete list would be very long.
Hitting
compose
then
this | and
then
this | renders
this |
| ' |
a |
á |
| ' |
A |
Á |
| " |
a |
ä |
| " |
A |
Ä |
| ` |
a |
à |
| ` |
A |
À |
| ~ |
a |
ã |
| ~ |
A |
à |
| ^ |
a |
â |
| ^ |
A |
 |
| c |
a |
ǎ |
| c |
A |
Ǎ |
| o |
a |
å |
| o |
A |
Å |
| _ |
a |
ā |
| _ |
A |
Ā |
| ; |
a |
ą |
| ; |
A |
Ą |
| b |
a |
ă |
| b |
A |
Ă |
| Vowels support most of the above |
|
Hitting
compose
then
this | and
then
this | renders
this |
| s |
s |
ß |
| , |
c |
çA cedilla , also known as cedilha or cédille, is a hook added under certain letters as a diacritical mark to modify their pronunciation.-Origin:...
|
| , |
C |
ÇA cedilla , also known as cedilha or cédille, is a hook added under certain letters as a diacritical mark to modify their pronunciation.-Origin:...
|
| O |
R |
® A trademark, trade mark, or trade-mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or...
|
| O |
C |
©Copyright is a legal concept, enacted by most governments, giving the creator of an original work exclusive rights to it, usually for a limited time...
|
| t |
m |
™ A trademark, trade mark, or trade-mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or...
|
| < |
< |
« |
| > |
> |
» |
| " |
< |
“ |
| " |
> |
” |
| ' |
< |
‘ |
| ' |
> |
’ |
| . |
. |
… |
| . |
^ |
· |
| x |
x |
× |
| - |
: |
÷ |
| ^ |
0 |
⁰ |
| ^ |
1 |
¹ |
| ^ |
2 |
² |
| ^ |
3 |
³ |
| 1 |
2 |
½ |
| 1 |
4 |
¼ |
| 3 |
4 |
¾ |
|
Hitting
compose
then
this | and
then
this | renders
this |
| s |
o |
§ The section sign , also called the "double S", "sectional symbol" or signum sectiōnis, is a typographical character used mainly to refer to a particular section of a document, such as a legal code. It is frequently used along with the pilcrow , or paragraph sign...
|
| / |
o |
ø |
| / |
O |
Ø |
| - |
d |
đ Đ , formed from D with the addition of a bar or stroke through the letter. This is the same modification that was used to create eth , but eth is based on an insular variant of d while đ is based on its usual upright shape...
|
| - |
D |
Đ Đ , formed from D with the addition of a bar or stroke through the letter. This is the same modification that was used to create eth , but eth is based on an insular variant of d while đ is based on its usual upright shape...
|
| d |
h |
ð Eth is a letter used in Old English, Icelandic, Faroese , and Elfdalian. It was also used in Scandinavia during the Middle Ages, but was subsequently replaced with dh and later d. The capital eth resembles a D with a line through the vertical stroke...
|
| D |
H |
Ð Eth is a letter used in Old English, Icelandic, Faroese , and Elfdalian. It was also used in Scandinavia during the Middle Ages, but was subsequently replaced with dh and later d. The capital eth resembles a D with a line through the vertical stroke...
|
| ~ |
n |
ñ Ñ is a letter of the modern Latin alphabet, formed by an N with a diacritical tilde. It is used in the Spanish alphabet, Galician alphabet, Asturian alphabet, Basque alphabet, Aragonese old alphabet , Filipino alphabet, Chamorro alphabet and the Guarani alphabet, where it represents...
|
| t |
h |
þ Thorn or þorn , is a letter in the Old English, Old Norse, and Icelandic alphabets, as well as some dialects of Middle English. It was also used in medieval Scandinavia, but was later replaced with the digraph th. The letter originated from the rune in the Elder Fuþark, called thorn in the...
|
| T |
H |
Þ Thorn or þorn , is a letter in the Old English, Old Norse, and Icelandic alphabets, as well as some dialects of Middle English. It was also used in medieval Scandinavia, but was later replaced with the digraph th. The letter originated from the rune in the Elder Fuþark, called thorn in the...
|
| a |
e |
æ Æ is a grapheme formed from the letters a and e. Originally a ligature representing a Latin diphthong, it has been promoted to the full status of a letter in the alphabets of some languages, including Danish, Faroese, Norwegian and Icelandic...
|
| A |
E |
Æ Æ is a grapheme formed from the letters a and e. Originally a ligature representing a Latin diphthong, it has been promoted to the full status of a letter in the alphabets of some languages, including Danish, Faroese, Norwegian and Icelandic...
|
| ! |
! |
¡ |
| ? |
? |
¿ |
| - |
L |
£ |
| = |
E |
€ |
| = |
Y |
¥ |
| | |
c |
¢ |
| o |
x |
¤ |
| / |
/ |
\ |
| o |
o |
° |
|
See also
- Modifier key
In computing, a modifier key is a special key on a computer keyboard that modifies the normal action of another key when the two are pressed in combination....
- Dead key
A dead key is a special kind of a modifier key on a typewriter or computer keyboard that is typically used to attach a specific diacritic to a base letter. The dead key does not generate a character by itself but modifies the character generated by the key struck immediately after...
- AltGr key
AltGr is a modifier key found on many computer keyboards and primarily used to type characters that are unusual for the locale of the keyboard layout, such as currency symbols and accented letters...
- Windows Alt keycodes
- Precomposed character
A precomposed character is a Unicode entity that can be defined as a combination of two or more other characters. A precomposed character may typically represent a letter with a diacritical mark, such as é...
- Combining character
In digital typography, combining characters are characters that are intended to modify other characters. The most common combining characters in the Latin script are the combining diacritical marks ....
External links
{{keyboard keys}}
{{DEFAULTSORT:Compose Key}}