Wikipedia:SUBST

To substitute, add subst: after the opening braces, as in {{subst:page name}}. For example: substitution {{subst:Medicine}} in contrast to transclusion {{Medicine}}. The contents of will be expanded (for any templates) and stored at each point where "{{subst:Medicine}}" is placed in a page. Note that ref-tags refuse to run "subst:" unless temporarily renamed as "<xref name=xx>" or similar.

The subst: keyword (short for "substitution") is used inside template code, placed as a prefix before the name of the template but within the curly braces ({{}}). It changes the way the software expands the template.

Ordinarily, a template will be expanded "on the fly"; that is, the template code on a page calls a separate page every time it is rendered. Although most page views are served from the cache, pages need to be rendered for previews, and rendered again when the page changes. When someone is editing a page with a normal template call, they see the template call.

Placing "subst:" inside the curly braces tells the software to permanently replace the template with the text of the template (i.e., the text that is on the template's article page when the template is added to the page). Therefore, {{template}} becomes {{subst:template}}, until you save the page. The next editor sees not the template call, but instead the text of the template when you saved; it does not change even if the original template is edited.

You can substitute a template tag by adding "subst:" to it. For example, use {{subst:test5}} instead of {{test5}}.

When this is a major component of an edit, it is strongly suggested that the template be mentioned in the edit summary (for instance, put "{{subst:test}}", "subst:test" or "test1 applied" in your edit summary) so other editors can easily see what you have done.

Additionally, when creating or editing templates that are commonly substituted, adding a hidden comment to the template page helps article editors to see how templates are being used (e.g. <!-- Substituted from -->).

This is a list of templates that should always be substituted, organized by namespace. Each list is ordered alphabetically with grouped series. This is not a comprehensive list, other less-used templates may also need to be substituted, see the template's documentation for details.

All of the templates listed in Category:User warning templates and Category:Welcome templates should be substituted. This does not apply to templates on the user page.

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