Help:Template: Difference between revisions

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{{Short description|Main technical help page on templates}}

{{Redirect-multi|2|H:T|Wikipedia:Template|help regarding tables|Help:Table|content guidelines|Wikipedia:Template namespace}}

{{For|lists of commonly used templates|WP:Template index}}

{{For-multi|lists of commonly used templates|Wikipedia:Template index|a quick introduction to templates|Help:A quick guide to templates}}

{{Redirect|H:T|help regarding tables|Help:Table}}

{{Redirect|Wikipedia:Template|content guidelines|Wikipedia:Template namespace}}

{{Pp-semi-indef}}

{{Wikipedia how to|H:T|WP:TEMPLATE}}

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Calling a template causes it to be either ''transcluded'' or ''substituted'' in the page that calls it (the ''target page'').

[[Wikipedia:Transclusion|Transcluding]] a template means that when MediaWiki <em>displays</em> the page, it treats the template as if it were directly in the page’s source. [[Substitutionary atonementWikipedia:Substitution|Substituting]] a template differs in that it inserts the content of the template permanently into the target page when it is <em>saved</em>

and subsequent editors cannot tell that it originated from a template.

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The value of a parameter can be an [[empty string]], such as when the pipe (<code>|</code>) or equals sign is followed immediately by the next pipe or the closing braces. For example, <code><nowiki>{{Template name|1=|2=test}}</nowiki></code> produces the same output as <code><nowiki>{{Template name||2=test}}</nowiki></code>. This is different from not specifying the parameter at all, which results in a default value, although templates are often coded so as to behave the same in both cases.

If a template call specifies a parameter which is not defined in the template, it has no effect. Editors sometime specify a parameter they know is not defined in the template, &mdash; Forfor example, editors sometimes include a parameter like {{tag|reason|open}} to add a brief explanation within the source as a [[Wikipedia:Manual of Style/Hidden text|hidden comment]]. (But some templates, such as [[Template:Requested move|Requested move]], are programmed to show the reason parameter if provided). Certain templates, especially complex ones like [[Wikipedia:Infobox|infoboxes]], may use the [[Module:Check for unknown parameters|check for unknown parameters module]] to alert editors about any [[:Category:Unknown parameters|unrecognized parameters]] to helpthey avoidcode unintentionalby errorsmistake.

If a parameter is specified as blank (e.g., {{para|1}}), it is treated as an empty string, which differs from leaving it out altogether (in which case the default value applies). However, templates are often coded to act the same in both cases.

==== Whitespace handling ====