View source for Help:Transclusion

{{Nutshell|Transclusion is a way to use content from one article, on another article without having to copy the content from one to the other. If the original content is changed, the change will automatically show in the article that is using the trancluded content.}}
{{Breadcrumbs|page=Help:Transclusion|url=|wikipedia=yes|openei=no|imwiki=no}}
[[File:Transclusion-multiple-foo.svg|thumb|An illustration of the scope of [[Help:Transclusion#How Transclusion Works|transclusion]]. |404x404px]]{{Clear right}}'''Transclusion''' means the inclusion of the content of one document in another document by reference. In USApedia, it refers to a function of the [[MediaWiki]] software that allows the content of one page to be included in the content of another page, by placing a reference to the source page in the wikitext of the target page. A page that is intended to be transcluded into  other pages is called a [[Help:Template|template]]. Changes made to a template are automatically reflected on all pages into which that template has been transcluded.

In addition to templates, it is possible to share portions of a page using [[#Labeled Section Transclusion|Labeled Section Transclusion]].

== Templates ==
{{Main|Help:Templates}}Templates are the main way in which transclusion occurs on USApedia, often with the use of [[Navboxes]] and [[Infoboxes]].

=== Noinclude, includeonly, and onlyinclude ===
<small>''The info is from [[Help:Templates#Noinclude,_includeonly,_and_onlyinclude]]''</small>
{{#lsth::Help:Templates|Noinclude, includeonly, and onlyinclude}}

== Labeled Section Transclusion ==
{{Main|Help:Labeled Section Transclusion}}
Labeled Section Transclusion allows the transclusion of a specific section of a page rather than an entire page.
{{#lsth:Help:Labeled Section Transclusion|Best practice usage within USApedia}}

== How Transclusion Works ==
To '''transclude''' any '''source''' page (within a single MediaWiki project, such as en:Wikipedia), use the following code in the '''target''' page: 

<code><nowiki>{{SOURCEPAGE}}</nowiki></code>

Any time you write the code (<code><nowiki>{{SOURCEPAGE}}</nowiki></code>) in a target page, you are telling Wikipedia software to put the entire content of <code><nowiki>SOURCEPAGE</nowiki></code> in the target page.

In the example below, look at target page '''A''' and <code><nowiki>SOURCEPAGE</nowiki></code> '''B'''.

If '''B''' is transcluded in '''A''', Wikipedia software will include ''in that specific place'' not the code (<code><nowiki>{{B}}</nowiki></code>) itself but the content of source page '''B''' (which is just the word ''foo''). 

The top row shows how target pages '''A''', '''P''', and '''Q''' will look with the changes in code seen in the bottom row to transclude source page '''B'''. Note the position of the code in each example target page. 

The source page content, ''foo'', will not be highlighted or boxed on the target page. (''Foo'' is in a light blue box here for ease of illustration and understanding.)

<div style="margipadding: 0.5em;">[[File:Transclusion-multiple-foo.svg|link=Special:FilePath/Transclusion-multiple-foo.svg]]</div>
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Transclusion creates a "live" link between a source page and the target page(s) where the source page's contents appear. This means that when you edit a source page, you will be updating its content across all the target pages that include it. Let's say you create a source page in Wikipedia with the address, date, and time of a local Wikimedia event that you want to invite 50 local editors to. Next, you transclude the invitation source page onto your talk page as well as the talk pages of the other 50 editors. A week later you discover the place for the event must be moved. You would then update the source page, and the new address will automatically appear on all the other attendees' talk pages. You could also tell the editors to invite people you may have missed. They could then simply transclude the invitation source page into other editors' talk pages themselves.

Remember to be extremely careful about editing any source page, especially if it contains transclusions from other source pages. Breaking existing transclusions in a source page is called '''breakage'''. Please avoid breakage(s) because not only the larger source page you are editing and all the target pages that include it will be affected. So will both the already embedded (now broken) source page that was used to add content to the larger source page, as well as every target page where the embedded source page was transcluded.

== See also ==
* [[Help:Templates]]
* [[Help:Labeled Section Transclusion]]
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