Editing AltGr key (section)

== X Window System ==
In the [[X Window System]] (Linux, BSD, Unix), AltGr can often be used to produce additional characters with almost every key on the keyboard. 
Furthermore, with some keys, AltGr will produce a [[dead key]]; for example on a [[Keyboard layout#UK|UK keyboard]], [[semicolon]] can be used to add an [[acute accent]] to a base letter, and left [[square bracket]] can be used to add a [[trema (diacritic)|trema]]:
* {{keypress|AltGr|<nowiki>;</nowiki>}} followed by {{keypress|E}} → <big>é</big>
* {{keypress|AltGr|<nowiki>[</nowiki>}} followed by {{keypress|Shift|O}} → <big>Ö</big>

This use of dead keys enables one to type a wide variety of [[precomposed character]]s that combine various diacritics with either uppercase or lowercase letters, achieving a similar effect to the [[Compose key]].

===Keyboard maps===

Below are some diagrams and examples of country-specific key maps. For the diagrams, the grey symbols are the standard characters, yellow is with {{keypress|shift}}, red is with {{keypress|AltGr}}, and blue is with {{keypress|Shift|AltGr}}.

====Danish keyboard====

The Danish keymap features the following key combinations:
* {{keypress|AltGr|Shift|Q}} → <big>Ω</big>
* {{keypress|AltGr|O}} → <big>œ</big>
* {{keypress|AltGr|M}} → <big>{{not a typo|µ}}</big>

====Italian keyboard====
The Italian keymap includes, among other combinations, the following:
{{Col-begin}}
{{Col-break|width=25%}}
* {{keypress|AltGr|H}} → <big>ħ</big>
* {{keypress|AltGr|ì}} → <big>~</big>
{{Col-break}}
* {{keypress|AltGr|'}} → <big>`</big>
* {{keypress|AltGr|<nowiki>;</nowiki>}} → <big>×</big>
{{Col-end}}

==== Norwegian keyboard ====
[[File:Norwegian X Window key map with its AltGr combinations.png|450px|thumb|center|The complete Norwegian X Window key map with its AltGr combinations]]

==== Polish keyboard ====
The Polish keymap on X-based systems features changed combination for € sign:
* {{keypress|AltGr|5}} → <big>€</big>
{{keypress|AltGr|U}} results in ↓ instead.
It also introduces several symbols and characters from different languages, including among others:
* {{keypress|AltGr|T}} → <big>ß</big>
* {{keypress|AltGr|P}} → <big>þ</big>
* {{keypress|AltGr|D}} → <big>ð</big>
* {{keypress|AltGr|Q}} → <big>π</big>
* {{keypress|AltGr|Shift|Q}} → <big>Ω</big>
* {{keypress|AltGr|M}} → <big>{{not a typo|µ}}</big>
* {{keypress|AltGr|Shift|M}} → <big>∞</big>
* {{keypress|AltGr|F}} → <big>æ</big>
* {{keypress|AltGr|W}} → <big>œ</big>

==== Swedish keyboard ====
[[File:KB Sweden AltGr.svg|thumb|450px|center|The complete Swedish X Window key map with its AltGr combinations]]