Dead key
Encyclopedia
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 (complete) character by itself but modifies the character generated by the key struck immediately after. Thus, a dedicated key is not needed for each possible combination of a diacritic and a letter, but rather only one dead key for each diacritic is needed, in addition to the normal base letter keys.
For example, if a keyboard has a dead key for the grave accent
(`), the French character à can be generated by first pressing and then , whereas è can be generated by first pressing and then . Usually, the diacritic in an isolated form can be generated with the dead key followed by space, so a plain grave accent can be typed by pressing and then .
On a typewriter, the dead-key functionality is accomplished mechanically by striking the diacritical mark without advancing the carriage (thus, the following letter will strike the same spot on the paper). By construction, this has no restrictions on a typewriter, so one could place an acute accent
(
Computers do not, however, work this way. On a computer, the dead key temporarily changes the mapping of the keyboard for the next keystroke, so instead of the normal letter, a precomposed
variant of it with the appropriate diacritic is generated. Each combination of a diacritic and a base letter must be specified in the character set and supported by the font
in use. As there is no precomposed character to combine the acute accent with the letter q, striking and then is likely to result in ´q, with the accent and letter as separate characters, or in some systems the invalid typing sequence may be discarded silently. (Using the combining character
s available in the Unicode
character set, it may be possible to generate a combination that more or less looks like a q with an acute accent – q́ – but this is a technique quite distinct from the dead key functionality.)
, places some dead keys directly on similar-looking punctuation marks. Old computer systems, such as the MSX
, often had a special key labeled dead key, which in combination with the Ctrl and Shift
keys could be used to add some of the diacritics commonly needed in the Western Europe
an languages (
In the absence of a default dead key, even a normal printing key can temporarily be altered to function as a dead key by simultaneously holding down another modifier key (typically AltGr
or Option
). In Microsoft Word
, using the Control key
with a key that usually resembles the diacritic (e.g.
) acts as a dead key.
On the Macintosh
, many keyboard layouts employ dead keys. In the U.S. layout, the following selection of dead keys appears: → á, é, í, ó, ú → à, è, ì, ò, ù → ä, ë, ï, ö, ü, ÿ → â, ê, î, ô, û → ã, õ, ñ
For example, when are first pressed simultaneously and then followed by , the result is á. On a Macintosh, pressing one of these Option-key combinations creates the accent and highlights it, then the final character appears when the key for the base character is pressed. However, some diacritically-marked Latin letters less common in the Western European languages, such as ŵ
(used in Welsh
) or š
(used in many Eastern Europe
an languages), cannot be typed with the U.S. layout, which predates Unicode
and only provides access to characters found in the legacy Mac Roman character set. Access to many more diacritics is provided by the U.S. Extended keyboard layout.
In AmigaOS
, dead keys are generated by pressing in combination with (acute), (grave), (circumflex), (tilde) or (trema) (e.g., the
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....
on a typewriter
Typewriter
A typewriter is a mechanical or electromechanical device with keys that, when pressed, cause characters to be printed on a medium, usually paper. Typically one character is printed per keypress, and the machine prints the characters by making ink impressions of type elements similar to the pieces...
or computer keyboard
Computer keyboard
In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
that is typically used to attach a specific diacritic
Diacritic
A 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 a base letter
Letter (alphabet)
A letter is a grapheme in an alphabetic system of writing, such as the Greek alphabet and its descendants. Letters compose phonemes and each phoneme represents a phone in the spoken form of the language....
. The dead key does not generate a (complete) character by itself but modifies the character generated by the key struck immediately after. Thus, a dedicated key is not needed for each possible combination of a diacritic and a letter, but rather only one dead key for each diacritic is needed, in addition to the normal base letter keys.
For example, if a keyboard has a dead key for the grave accent
Grave accent
The grave accent is a diacritical mark used in written Breton, Catalan, Corsican, Dutch, French, Greek , Italian, Mohawk, Norwegian, Occitan, Portuguese, Scottish Gaelic, Vietnamese, Welsh, Romansh, and other languages.-Greek:The grave accent was first used in the polytonic orthography of Ancient...
(`), the French character à can be generated by first pressing and then , whereas è can be generated by first pressing and then . Usually, the diacritic in an isolated form can be generated with the dead key followed by space, so a plain grave accent can be typed by pressing and then .
Usage
A dead key is different from a typical modifier key (such as or ) in that, rather than being pressed and held while another key is struck, the dead key is pressed and released before striking the key to be modified. In some computer systems, there is no indication to the user that a dead key has been struck, so the key appears dead, but in some text-entry systems the diacritic is displayed along with an indication that the system is waiting for another keystroke to complete the typing sequence.On a typewriter, the dead-key functionality is accomplished mechanically by striking the diacritical mark without advancing the carriage (thus, the following letter will strike the same spot on the paper). By construction, this has no restrictions on a typewriter, so one could place an acute accent
Acute accent
The acute accent is a diacritic used in many modern written languages with alphabets based on the Latin, Cyrillic, and Greek scripts.-Apex:An early precursor of the acute accent was the apex, used in Latin inscriptions to mark long vowels.-Greek:...
(
´) on a q, for example.Computers do not, however, work this way. On a computer, the dead key temporarily changes the mapping of the keyboard for the next keystroke, so instead of the normal letter, a precomposed
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...
variant of it with the appropriate diacritic is generated. Each combination of a diacritic and a base letter must be specified in the character set and supported by the font
Font
In 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. As there is no precomposed character to combine the acute accent with the letter q, striking and then is likely to result in ´q, with the accent and letter as separate characters, or in some systems the invalid typing sequence may be discarded silently. (Using the combining character
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 ....
s available in the Unicode
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
character set, it may be possible to generate a combination that more or less looks like a q with an acute accent – q́ – but this is a technique quite distinct from the dead key functionality.)
Dead keys on various keyboard layouts
A key may function as a dead key by default, and many non-English keyboard layouts in particular have dead keys directly on the keyboard. The basic US keyboard does not have any dead keys, but the US-International keyboard layout, available on Windows and the X Window SystemX Window System
The 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...
, places some dead keys directly on similar-looking punctuation marks. Old computer systems, such as the MSX
MSX
MSX was the name of a standardized home computer architecture in the 1980s conceived by Kazuhiko Nishi, then Vice-president at Microsoft Japan and Director at ASCII Corporation...
, often had a special key labeled dead key, which in combination with the Ctrl and Shift
Shift key
The 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...
keys could be used to add some of the diacritics commonly needed in the Western Europe
Western Europe
Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...
an languages (
´, `, ˆ and ¨) to vowels that were typed subsequently.In the absence of a default dead key, even a normal printing key can temporarily be altered to function as a dead key by simultaneously holding down another modifier key (typically AltGr
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...
or Option
Option key
The 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 Microsoft Word
Microsoft Word
Microsoft Word is a word processor designed by Microsoft. It was first released in 1983 under the name Multi-Tool Word for Xenix systems. Subsequent versions were later written for several other platforms including IBM PCs running DOS , the Apple Macintosh , the AT&T Unix PC , Atari ST , SCO UNIX,...
, using the Control key
Control key
In computing, a Control key is a modifier key which, when pressed in conjunction with another key, will perform a special operation ; similar to the Shift key, the Control key rarely performs any function when pressed by itself...
with a key that usually resembles the diacritic (e.g.
^ for a circumflexCircumflex
The circumflex is a diacritic used in the written forms of many languages, and is also commonly used in various romanization and transcription schemes. It received its English name from Latin circumflexus —a translation of the Greek περισπωμένη...
) acts as a dead key.
On the Macintosh
Macintosh
The Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...
, many keyboard layouts employ dead keys. In the U.S. layout, the following selection of dead keys appears: → á, é, í, ó, ú → à, è, ì, ò, ù → ä, ë, ï, ö, ü, ÿ → â, ê, î, ô, û → ã, õ, ñ
For example, when are first pressed simultaneously and then followed by , the result is á. On a Macintosh, pressing one of these Option-key combinations creates the accent and highlights it, then the final character appears when the key for the base character is pressed. However, some diacritically-marked Latin letters less common in the Western European languages, such as ŵ
W
W is the 23rd letter in the basic modern Latin alphabet.In other Germanic languages, including German, its pronunciation is similar or identical to that of English V...
(used in Welsh
Welsh language
Welsh is a member of the Brythonic branch of the Celtic languages spoken natively in Wales, by some along the Welsh border in England, and in Y Wladfa...
) or š
Š
The grapheme Š, š is used in various contexts, usually denoting the voiceless postalveolar fricative. In the International Phonetic Alphabet this sound is denoted with , but the lowercase š is used in the Americanist phonetic notation, as well as in the Uralic Phonetic Alphabet.For use in computer...
(used in many Eastern Europe
Eastern Europe
Eastern Europe is the eastern part of Europe. The term has widely disparate geopolitical, geographical, cultural and socioeconomic readings, which makes it highly context-dependent and even volatile, and there are "almost as many definitions of Eastern Europe as there are scholars of the region"...
an languages), cannot be typed with the U.S. layout, which predates Unicode
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
and only provides access to characters found in the legacy Mac Roman character set. Access to many more diacritics is provided by the U.S. Extended keyboard layout.
In AmigaOS
AmigaOS
AmigaOS is the default native operating system of the Amiga personal computer. It was developed first by Commodore International, and initially introduced in 1985 with the Amiga 1000...
, dead keys are generated by pressing in combination with (acute), (grave), (circumflex), (tilde) or (trema) (e.g., the
ALT-F combination followed by the a key generates á and ALT-F followed by e generates é, whereas ALT-G followed by a generates à and ALT-G followed by e generates è).See also
- Modifier keyModifier 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....
- Compose keyCompose keyA compose key, available on some computer keyboards, is a special kind of modifier key designated to signal the software to interpret the following sequence of two keystrokes as a combination in order to produce a character not found directly on the keyboard...
- AltGr keyAltGr keyAltGr 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 characterPrecomposed 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...
- Combining characterCombining characterIn 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 ....