View source for Template:Category pair/doc

{{Documentation subpage}}
{{High-use|3007}}
<!-- PLEASE ADD CATEGORIES AT THE BOTTOM OF THIS PAGE -->
{{Lua|Module:Check for unknown parameters}}

==Usage==
Typical usage should be on dissimilar preceding/succeeding categories, or where a large gap exists in otherwise sequential categories. For similarly named sequential categories with gaps less than 5 years, use {{tl|Navseasoncats}} instead.

* For 2 adjacent categories, a preceding <code>Category:NAME1</code>, and a succeeding <code>Category:NAME2</code>, place:
: {{tlx|Category pair|NAME1|NAME2}}
: at the top of the category page. Each category is displayed only if it exists. If neither category exists, nothing will be displayed.

* If there is no succeeding category, you may simply place:
: {{tlx|Category pair|NAME1}}
: at the top of the category page.

* If there is no preceding category, then leave the first parameter empty, and simply place:
: {{tlx|Category pair|<nowiki></nowiki>|NAME2}}
: at the top of the category page.

==Examples==
;Preceding and succeeding categories, both exist
* {{tlx|Category pair|1934 FIFA World Cup|1950 FIFA World Cup}} → {{Category pair|1934 FIFA World Cup|1950 FIFA World Cup}}

;Preceding category only, which exists
* {{tlx|Category pair|1934 FIFA World Cup}} → {{Category pair|1934 FIFA World Cup}}

;Succeeding category only, which exists
* {{tlx|Category pair|<nowiki></nowiki>|1950 FIFA World Cup}} → {{Category pair||1950 FIFA World Cup}}

;Preceding and succeeding categories, only preceding exists
* {{tlx|Category pair|1934 British Empire Games|1942 British Empire Games}} → {{Category pair|1934 British Empire Games|1942 British Empire Games}}

;Preceding and succeeding categories, only succeeding exists
* {{tlx|Category pair|1946 British Empire Games|1954 British Empire and Commonwealth Games}} → {{Category pair|1946 British Empire Games|1954 British Empire and Commonwealth Games}}

; Two non-existent categories, so no output:
* {{tlx|Category pair|AD 10 FIFA World Cup|AD 18 FIFA World Cup}} → {{Category pair|AD 10 FIFA World Cup|AD 18 FIFA World Cup}}

== Error checking ==
Only the first two parameters are processed, others are ignored.

If more than two parameters are supplied, a warning message is shown when the page is previewed. When it is saved, the page is added to the hidden tracking category: [[:Category:Pages using category pair with more than 2 parameters]].

If more than two parameters are supplied, the template is unlikely to do what the editor intended. For <code>Category:NAME1</code>, <code>Category:NAME2</code>, and <code>Category:NAME3</code>, for example:
* {{tlc|Category pair|NAME1|NAME2|NAME3}} will ignore <code>Category:NAME3</code>, and
* {{tlc|Category pair|NAME1||NAME2}} will ignore <code>Category:NAME2</code>, because a duplicate <code>|</code> character between the two categories causes <code>Category:NAME2</code> to be the third parameter rather the second.

== Tracking categories ==
* {{clc|Pages using category pair with no output}}
: If neither parameter is a category which currently exists the template will produce no output. This is ''not necessarily an error''; the other categories may simply be part of an incomplete series which will be completed in due course
* {{clc|Pages using category pair with more than 2 parameters}}
: See above: [[#Error checking|Error checking]]

==See also==
* {{tl|Navseasoncats}} — for similarly named sequential categories
* {{tl|Preceding category}}
* {{tl|Succeeding category}}

{{Category hatnote templates}}

<includeonly>{{sandbox other||
[[Category:Internal category-link templates]]
[[Category:Hatnote templates for category pages]]
[[Category:Templates that add a tracking category]]
}}
</includeonly>