For example, one template can display "football" for |engvar=en-UK articles, and "soccer" for |engvar=en-US articles.

1. Articles specify the English variety parameter for relevant templates like {{example|engvar=en-US}}. They do not use {{engvar}}.
2. Templates use {{engvar}}. It should not forget to pass-through |engvar={{{engvar|}}}

...
| label3 = {{engvar |defaultWord=Colour |defaultLang=en-UK |en-US=Color |engvar={{{engvar|auto}}} }}
|  data3 = {{{color|}}}
| label4 = {{engvar |defaultWord=Football |defaultLang=en-UK |en-US=Soccer |engvar={{{engvar|auto}}} }} team
|  data4 = {{{team|}}}
...

The |defaultWord= be shown by default. But if an article asks for an English variety that has a corresponding parameter specified in the template, the value will be shown.

In the example, the template specified a British English word as default whenever no |engvar= is specified by the article. The word can be changed in an American English article by that article specifying |engvar=en-US. The fallback 'auto' value means it will try to determine the language based on templates like {{Use British English}} or {{Use American English}} being present on the page if no engvar is specified.

Note: {{engvar}} is unrelated to parameter names like |color= vs. |colour=. See programming option |data3={{{color|{{{colour|}}} }}}

Consider an example template, a fictive {{infobox personal likes}}. The demo is encoded in {{Engvar/doc/infobox demo}}.

{{infobox
| title       = Personal likes
| above       = Demo: using [[WP:ENGVAR|WP:Engvar]] in templates
| abovestyle  = background:#ddd; font-weight:normal; font-size:smaller;
| headerstyle = background:lemonchiffon
| label1      = Home country
| data1       = {{{home country|}}}
| header2     = {{engvar|defaultWord=Favourite |defaultLang=en-GB | engvar={{{engvar|auto}}}
                        |en-US=Favorite }} things
| label3      = {{engvar|defaultWord=Colour |defaultLang=en-GB | engvar={{{engvar|auto}}}
                        |en-US=Color }}
| data3       = {{{color|}}}
| label4      = {{engvar|defaultWord=Football |defaultLang=en-GB | engvar={{{engvar|auto}}}
                        |en-US=Soccer |en-AU=Association Football}} team
| data4       = {{{team|}}}
| below       = In this demo 'article', the template parameter is set: {{para|1=engvar|2={{{engvar|(unspecified)}}}}}
| belowstyle  = background:#ddd;
}}

{{Engvar/doc/infobox demo
| home country = Wales
| color = Blue
| team  = [[FC Kuusysi]]
<!-- |engvar= not set; expect defaults -->
}}

{{Engvar/doc/infobox demo
| home country = Alaska
| color = Blue
| team  = [[FC Kuusysi]]
| engvar= en-US
}}

{{Engvar/doc/infobox demo
| home country = Australia
| color = Blue
| team  = [[FC Kuusysi]]
| engvar= Australian
}}

Currently, {{infobox element}} has five {{engvar}} words. Phosphorus shows |engvar=en-UK despite the |engvar=en-US default.

{{engvar
| defaultWord =
| defaultLang =
| engvar = <!-- Pass-through the editor's choice, set to 'auto' to automatically detect -->
| en-XX = <!-- add country code for XX, and the nation language word -->
| en-YY = <!-- add more varieties as might be needed -->
| engvarCat =  <!-- '=no' will suppress message category in article page -->
| fallback = <!-- set to 'true' to allow commonwealth languages to fallback to 'en-GB'. False by default unless engvar='auto'. -->
}}

{{example
| engvar =
| engvarCat =
}}

In the template, use the exact ISO-code as the parameter name like |en-GB=vapour. Write |en-US=soccer not |American English=soccer. Needed varieties have articles using the template and words differing from the default.

There is backwards compatibility for leeway in articles. |engvar=en-US, |engvar=United States, |engvar=US can all show the |en-US=football variety.

Articles with an invalid |engvar= will be placed in the hidden maintenance category Category:Articles using an unknown Template:Engvar option. Articles listed may need editing.

An article's requested |engvar= may be unspecified in the template. For example, if an article uses {{example|engvar=South African English}} but the template has no |en-ZA=, then the template will return |defaultWord=default color name. The category will not be used.

When this categorization is not desired for a whole template, set |engvarCat=no in the template

Otherwise pass-through this setting from the article: |engvarCat={{{engvarCat|yes}}}. This allows the editor to switch categorization off per article.

Articles are sorted by |engvarCatSort= or {{pagename}} by default. Note that other templates will fill this category. Set this parameter like |engvarCatSort=Personal prefs in a template to group its listings under "P".

• HELP:ENGVAR
• Category:Articles using an unknown Template:Engvar option
• ISO 3166-1 alpha-2 -- The 2-letter country code
• {{#invoke:Engvar|explain|...}} - debugging