Categories are a wiki feature which enables pages to be automatically added to listings. It helps to keep a structure throughout the site for easier navigation for pages with similar subjects.
A category page will list the pages that have been added to a particular category. In certain category's you may also see that there is even subcategory's listed for a particular category. This basically just helps in the tree-like structure in the particular category.
Wiki software maintains tables of categories, to which any editable page can be added to a particular category. To add a page to a category, include "[[Category:Category name]]" or "[[Category:Category name|Sortkey]]" in that page's editable text. The categories to which a page belongs appear in a box at the bottom of the page.
Assign Pages to Categories
A page belongs in a category if the editable text contains a declartion for that category. A category declaration takes the form [[Category:Category name]] or [[Category:Category name|Sortkey]]. Since the declaration must be processed, keep in mind it will not work if it appears between <nowiki>...</nowiki> or <includeonly>...</includeonly> tags, or in a comment. Also note that a category cannot begin with a lowercase letter, and if it does, it will be interpreted as an upper case letter.
If a page has been categorized, you will notice a box on the bottom of the page known as the category box. It will list the categorys that the particular page you are on belongs to. Just like other links in a wiki, if the category does not exist, it will appear as a red link.
NOTE: When starting or editing a repair article for any vehicle make sure you include [[Category:Repairs]] to have the repair show up on the front page in the recent repairs!
Hide a Category
When the magic word __HIDDENCAT__ is placed on a category page, that category will become hidden, which means that it will not be displayed on the pages belonging to that category. The feature is mostly used to prevent project maintenance categories from showing up to ordinary readers on article pages.
Exceptions for when idden categories are displayed (although listed as hidden):
- on category pages (whether as parent categories or subcategories);
- at preview during editing;
- if the user has selected "Show hidden categories" in user preferences.
Searching within Category's
In addition to browsing through hierarchies of categories, it is possible to use the search tool to find specific articles in specific categories. To search for articles in a specific category, type incategory:"CategoryName" in the search box.
For example, enter the search text
- incategory:"BMW" incategory:"Cars"
to find the articles that are common to both categories.
Similarly, an "OR" can be added to join the contents of one category with the contents of another. For example, enter
- incategory:"BMW" OR incategory:"Cars"
to return all pages that belong to either (or both) of the categories.
- Note that using search to find categories will not find articles which have been categorized using templates.
Listing the Category's
Special:Categories provides an alphabetic list of all categories, with the number of members of each; this number does not include the content of the subcategories, but it includes the subcategories themselves, i.e., each counting as one.
The above list contains all categories that have members, regardless of whether they have corresponding category pages. To list all existing category pages (regardless of whether they have members), use Special:AllPages/Category:.