Administrators: Please do not delete this category as empty! This category may be empty occasionally or even most of the time.

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. This category is hidden on its member pages—unless the corresponding user preference (Appearance → Show hidden categories) is set. 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. These categories also serve to aggregate members of several lists or sub-categories into a larger, more efficient list (discriminated by classifications).

This category contains pages transcluding Template:Non-free use rationale poster ( 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.

Unknown parameters can be detected using Module:Check for unknown parameters in the template. To show the information listed here on a category page, use {{ Unknown parameters category}} on the category page.