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This is a maintenance 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.
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.
The subcategories of this category are hidden categories. To add a category to this category, add
This category contains hidden categories. Unlike normal categories, these are not displayed at the bottom of pages that are included in them, and are therefore hidden from readers.
Typically categories should be hidden if they are concerned with the maintenance or administration of the Wikipedia project itself but include mainspace articles.
Previewing a page whilst editing it will list the hidden categories used at the bottom of the page. If you have created a user account, you can make hidden categories show up next to normal categories at the bottom of all pages by setting the user preference 'Show hidden categories'.