Compose key
From Wikipedia, the free encyclopedia
On some computer systems, a compose key is a key which is designated to signal the software to interpret the next keystrokes as a combination in order to produce a character not found on the keyboard.
For example, typing compose, then a, then e may produce the AE ligature, æ. Typing compose, then ', then e can yield an e with an acute accent, é.
The compose key is known as "Multi_key" in the X Window System. In XFree86 and X.Org Server, many keyboard layouts have a variant that maps Multi_key to some key, usually (on PC keyboards) to either of the Windows keys (most often the "Context Menu" key, since "Start" is already used to open the start menu). It can also be specified in XkbOptions (for example, "compose:rwin"). Multi_key can also be assigned with the xmodmap(1) utility.
| Hitting compose then this |
and then this |
renders this |
|---|---|---|
| ' | a | á |
| ' | A | Á |
| " | a | ä |
| " | A | Ä |
| ` | a | à |
| ` | A | À |
| ~ | a | ã |
| ~ | A | Ã |
| ^ | a | â |
| ^ | A | Â |
| o | a | å |
| o | A | Å |
| s | s | ß |
| Vowels support most of the above | ||
| , | c | ç |
| , | C | Ç |
| O | R | ® |
| O | C | © |
| < | < | « |
| > | > | » |
| . | . | · |
| x | x | × |
| - | : | ÷ |
| ^ | 0 | ° |
| ^ | 1 | ¹ |
| ^ | 2 | ² |
| ^ | 3 | ³ |
| s | o/0 | § |
| 1 | 2 | ½ |
| 1 | 4 | ¼ |
| 3 | 4 | ¾ |
| / | O | ø |
| / | O | Ø |
| - | d | ð |
| - | D | Ð |
| ~ | n | ñ |
| t | h | þ |
| T | H | Þ |
| a | e | æ |
| A | E | Æ |
| ! | ! | ¡ |
| ? | ? | ¿ |
| - | L | £ |
| = | E | € |
| = | Y | ¥ |
| | | c | ¢ |
| o | x | ¤ |
| / | / | \ |
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, although it is part of any standard keyboard since the 1990s. In particular the $ compose sequence ceased to work on modern systems. The historic backslash sequence (compose-//) witnesses of the similar situation for this key and is still working on modern systems.
The table shown contains the current common compositions for Xorg 7. Other compositions may work, based on the de-facto Sun/DEC/Falco standard. Particularly for modern systems which support customisable compose sequences and Unicode, the table would be far from complete. Given the vast number of sequences permissible and the vast number of characters desirable in Unicode, a complete table would be incredibly long.
The compose key can be found on the LK201 family of keyboards from Digital Equipment Corporation and its successors. The key can also be found on keyboards from Sun Microsystems.
On Mac OS X, the "option" key provides access to some extended characters. For example, holding down option and pressing a results in å; holding down option and pressing ` will create a highlighted ` character which will be added to the next letter if possible - so if an e is then pressed, the resultant character is è, while if an r is pressed the two characters are not compatible so the result is `r.
Microsoft Windows does not use a compose key, but it does support dead keys and AltGr for many characters. Other characters can be generated by holding down Alt, and then typing the ASCII code or Unicode code corresponding to the desired character on the numeric keypad. A few programs such as putty also directly provide Compose key support.
There is also an Open Source utility available called AllChars that emulates the compose key using a selectable modifier key like Control or Shift. What characters it can create depend on the currently chosen code page and screen font, but most Western, Central, and Eastern European character sets are covered by predefined configuration files. The compose combinations can be customized by the user.
[edit] External links
- XFree86 Compose Key character map by XFree86
- Everything2's list of Compose Key combinations
- SUN's Compose Key combinations used under CDE
- Setting up Compose Key in the X Window System
- Using the Compose Key in the X Window System
- A Unix utility to lookup the Compose Key for the specified character
- AllChars, an open-source utility that emulates the Compose key under MS-Windows
- JLG Extended Keyboard Layout - yet another utility based on the Compose Key mechanism under Windows
| Esc | F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8 | F9 | F10 | F11 | F12 | PrtSc | ScrLk | Pause | |||||||||
 |
Ins | Home | PgUp | NumLk | / | * | - | |||||||||||||||||
| Del | End | PgDn | 7 | 8 | 9 | + | ||||||||||||||||||
| 4 | 5 | 6 | ||||||||||||||||||||||
| ↑ | 1 | 2 | 3 | Ent | ||||||||||||||||||||
| ← | ↓ | → | 0 | . | ||||||||||||||||||||
|
||||||||||||||||||||
