Category:Hidden categories

From Festipedia, hosted by the FR Heritage Group

Hidden categories are those that have been tagged with the magic word __HIDDENCAT__.

Hidden categories are not listed on articles by default. If you are wondering why the category you have added to an article has not appeared, check to see if the category is hidden. Editing a page will list hidden categories at the bottom of the page, below the list of templates used.

Hidden categories are not hidden on category pages.

You can turn this feature off by clicking the box to "Show hidden categories", under the "Misc" tab at "my preferences".