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This category may be empty occasionally or even most of the time.

This is an administrative category, used for maintenance of the Wikipedia project. It is not part of the encyclopedia and contains non-article pages, or groups articles by status rather than subject. Do not include this category in content categories (except for eponymous maintenance categories).

This is a tracking category. It builds and maintains a list of pages primarily for the sake of the list itself. They are not part of the encyclopedia's categorization scheme.

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• These categories can be used to track, build and organize lists of pages needing "attention en masse" (for example, pages using deprecated syntax), or that may need to be edited at someone's earliest convenience.
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This category contains pages transcluding Template:Math (talk) with unknown parameters (undefined, misspelled, etc.).

Pages are typically sorted alphabetically by the unknown parameter that is used, e.g. pages using unknown parameter |foo= will be sorted under "F". The name of the page is typically used as a secondary sort key. See additional information from the Parameter usage report for Template:Math.

Note: the following code habit is not an error.

{{math|{1, 2, 3}|}} is not an error, and should be left unedited.

In code: the indices can range over the set {{math|{1, 2, 3}|}}

Text shown: "... the indices can range over the set {1, 2, 3}"

The extra pipe symbol in {{math|{1, 2, 3}|}} is unused but does not corrupt the math text. It helps understanding the input text (distinguishing the various }-symbol).

It produces a categorisation here, and a Warning: "unknown parameter |2=". However, since it is helpful, it is not an error, and it should not be edited out. As of Jan 2021^[update], 18 articles are listed with this feature.