Unexpected use of template ((12)) - see Template:12 for details.^[1]

This is the template sandbox page for Template:12 (diff).

Template documentation

Templates ((1)), ((2)), ((3)), etc. warn readers/editors that a typo exists in the page they are reading/editing. If ((12)) is called, you probably meant the parameter 12 (as (({12))} with triple braces), but in fact only double braces were used, invoking ((12)). In addition to a warning, it also adds pages to Category:Templates with incorrect parameter syntax. For more information on how template parameters work, see mw:Help:Templates#Parameters.

However, the most problems have been caused by omitting the first brace "{" of a parameter and getting ((12))}, as invoking Template:12 +"}" rather than parameter 12. This can be an insidious problem, especially when the transclusion of Template:12 is hidden, so that the effect is invisible to the person editing a page. For that reason, Template:12 now issues a warning to the user.

With that warning, the prior invisible access to Template:12 can now be understood to be a formerly unseen problem coded within a page.

Note: this will also pick up several variations such as ((12|)) for (({12|))} and (({12)).

Periodically, people check what-links-here to see if anyone has accidentally invoked Template:12.

((1))
((2))
((3))
((4))
((5))
((6))
((7))
((8))
((9))
((10))
((11))
((12))
((13))
((14))
((15))
((16))
((17))
((18))
((19))
((20))
((21))
((22))
((23))
((24))
((25))
((26))
((27))
((28))
((29))
((30))

References

These references will appear in the article, but this list appears only on this page.

^ Show template documentation
Templates ((1)), ((2)), ((3)) etc warn readers/editors that a typo exists in the page they are reading/editing. If ((12)) is called, you probably meant the parameter 12 (as (({12))} with triple braces), but in fact only double braces were used, invoking ((12)). In addition to a warning, it also adds pages to Category:Templates with incorrect parameter syntax.
However, the most problems have been caused by omitting the first brace "{" of a parameter and getting ((12))}, as invoking Template:12 +"}" rather than parameter 12. This can be an insidious problem, especially when the transclusion of Template:12 is hidden, so that the effect is invisible to the person editing a page. For that reason, Template:12 now issues a warning to the user.
With that warning, the prior invisible access to Template:12 can now be understood to be a formerly unseen problem coded within a page.
Note: this will also pick up several variations such as ((12|)) for (({12

Editors can experiment in this template's sandbox (edit | diff) and testcases (create) pages.
Subpages of this template.