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.
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 category may contain pages that use ((Authority control)) or are associated with the template, and which need attention. They are sorted under the various different issues, listed below.
A: Invalid QID specified with |additional= parameter.
D: A page is connected to a Wikidata item but has a |qid= parameter which does not match. (This parameter will be ignored by the template, but it's probably worth to check what has happened and remove the invalid parameter.)
L: One or more Wikidata items is lacking an English label so cannot be displayed.
N: Page has a non-existent authority control category. The most likely cause is that a new identifier has recently been added, but the editor has yet to create the corresponding categories.
P: Unrecognised property number in |suppress= parameter.
R: Additional parameter is a duplicate of qid parameter.
S: A page is using an unrecognised |state= parameter. It should be either collapsed, expanded or autocollapse. Any invalid values can be fixed or removed.
U: Categories listed here do not conform to any expected naming convention, rendering the template useless. The solution is to either remove the template from the category, or improve/update the module to accommodate the new category naming convention.