Dead Keys

Dead keys are most commonly used in European keyboard layouts; a diacritic is generally used as the dead key. An example of this can be found on the Finnish keyboard, where typing a diaeresis (U+00A8) will initially do nothing, but then typing any of the characters in the first column in Table 1 will cause the character in the second column of Table 1 to be displayed. For example, if a user types a diaeresis, followed by a small letter a, Latin small letter A diaeresis (ä) will be displayed.

Table : The Diaeresis dead key on the Finnish keyboard

The last two rows in gray of the above table are important to note. The first gray row is a common convention on most keyboards with dead keys; if you type the dead key and then a space, you will get the spacing version of the character. The second one is not a part of the keyboard layout definition, but is simply what happens if you type a dead key followed by a character that is not defined in the keyboard layout as a base character for that dead key: the deadkey is printed (input), followed by that second character. For example, Latin small letter C is not defined in the keyboard layout as being a base character for the diaeresis deadkey. If U+00A8 is typed, followed by 'c', those two code points will be input. No combining character will be created. While deadkeys are not limited to European keyboard layouts, that is where they are most commonly used.