This is a tracking category. It is used to build and maintain lists of pages—primarily for the sake of the lists themselves and their use in article and category maintenance. It is not part of the encyclopedia's categorization scheme. More information: This category is hidden on its member pages—unless the corresponding user preference (Appearance → Show hidden categories) is set. These categories are 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). Typically, tracking categories are automatically populated by templates invoked in pages or by the MediaWiki software (see Special:TrackingCategories for an overview of the latter).

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

This maintenance category contains pages where {{ Category series navigation}} or Module:Category series navigation uses an unknown parameter. This could be either:

• an unnamed parameter such as {{ Category series navigation|example}}, or {{ Category series navigation| }}, or
• a named unknown parameter such as {{ Category series navigation|catt = example}}, or {{ Category series navigation|decade = example}}.

To correct the problem, investigate the adjacent categories and the category hierarchy, then modify {{ Category series navigation}} as appropriate, being aware that the intended parameter (or lack thereof) might be necessary on the errored category or a surrounding category.

Pages in this category should only be added by Template:Category series navigation and Module:Category series navigation.