Graphene Theme Documentation Wiki:Categorization

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File:Category explanation.ogv

This page contains guidance on the proper use of the categorization function in Graphene Theme Documentation Wiki. For information on the mechanics of the function, category syntax, etc., see Help:Category. For quick answers, see the Categorization FAQ. For the category system itself, see Category:Contents.


The central goal of the category system is to provide links to all Graphene Theme Documentation Wiki articles in a hierarchy of categories which readers can browse, knowing essential, defining characteristics of a topic, and quickly find sets of articles on topics that are defined by those characteristics.

Categories are not the only means of enabling users to browse sets of related articles. Other tools which may be used instead of or alongside categories in particular instances include lists and navigation boxes. For a comparison of these techniques, see Categories, lists and navigation templates.

Every Graphene Theme Documentation Wiki article should belong to at least one category. This guide sets out the means to:

  • identify the defining characteristics of an article's topic,
  • create new categories if necessary,
  • categorise articles accordingly, and
  • organise and link inter-related categories.

The following sub-pages detail certain, specific aspects of the guide:

Defining characteristics

A central concept used in categorisation is that of the defining characteristics of a subject. A defining characteristic is one that reliable sources commonly and consistently define<ref>in prose, as opposed to a tabular or list form</ref> the subject as having—such as nationality or notable profession (in the case of people), type of location or region (in the case of places), etc. For example, here: "Caravaggio, an Italian artist of the Baroque movement ...", Italian, artist, and Baroque may all be considered to be defining characteristics of the subject Caravaggio. A category embodies one or more defining characteristic—how this is achieved in practice is described in the following sections.

Category organization

Categories are organized as overlapping “trees”, formed by creating links between inter-related categories. Any category may contain (or “branch into”) subcategories, and it is possible for a category to be a subcategory of more than one “parent” category. (A is said to be a parent category of B when B is a subcategory of A). <ref>Mathematically speaking, this means that the system approximates a directed acyclic graph.</ref>

There is one top-level category, Category:Contents. All other categories are found below this. Hence every category apart from this top one must be a subcategory of at least one other category.

There are two main kinds of category:

  • Topic categories are named after a topic (usually sharing a name with the Graphene Theme Documentation Wiki article on that topic). For example, Category:France contains articles relating to the topic France.
  • Set categories are named after a class (usually in the plural). For example, Category:Cities in France contains articles whose subjects are cities in France.

Sometimes, for convenience, the two types can be combined, to create a set-and-topic category (such as Category:Voivodeships of Poland, which contains articles about particular voivodeships as well as articles relating to voivodeships in general).

If logical membership of one category implies logical membership of a second, then the first category should be made a subcategory (directly or indirectly) of the second. For example, Cities in France is a subcategory of Populated places in France, which in turn is a subcategory of Geography of France.

Partial view of Graphene Theme Documentation Wiki's category system. Note how the arrows point downwards.

Categorizing pages

Often, an uncategorised article will fit into existing categories; to determine if suitable categories already exist:

  • check the categories of articles on similar topics (by looking at the category list at the bottom of those articles),
  • check likely parent categories.

It should be clear, from the name of an existing category, which pages it should contain; additional explanation however, is sometimes given in the text of the category page.

If you think a new category needs to be created, see What categories should be created below. If you don't know where to put an article, add the {{uncategorized}} template to it—other editors (such as those monitoring Graphene Theme Documentation Wiki:WikiProject Categories/uncategorized) will find good categories for it.

For information on whether and how to categorize pages other than articles, see Non-article and maintenance categories below.

Particular considerations for categorizing articles are as follows:

  • Articles should be categorized by the defining characteristics of the article topic. Categorization should not be made by the type of an article. A biographical article about a specific person, for example, does not belong in Category:Biography.
  • Categorization must be verifiable: it should be clear from verifiable information in the article why it was placed in each of its categories. Use the {{Category unsourced}} template if you find an article in a category that is not shown by sources to be appropriate, or the {{Category relevant?}} template if the article gives no clear indication for inclusion in a category.
  • Categorization must maintain a neutral point of view: categorizations appear on pages without annotations or referencing to justify or explain their addition; editors should be conscious of the need to maintain a neutral point of view when creating categories or adding them to articles. Categorizations should generally be uncontroversial; if the category's topic is likely to spark controversy, then a list article (which can be annotated and referenced) is probably more appropriate.
  • Each article should be placed in all of the most specific categories to which it logically belongs. This means that if a page belongs to a subcategory of C (or a subcategory of a subcategory of C, and so on) then it is not normally placed directly into C. For exceptions to this rule, see Eponymous categories and Non-diffusing subcategories below.
  • Articles on fictional subjects should not be categorized in a manner that confuses them with real subjects.
  • An article should never be left with a non-existent (redlinked) category on it. Either the category should be created, or else the link should be removed or changed to a category that does exist.
  • By convention, category declarations are placed at the end of the wikitext, but before any stub templates (which themselves transclude categories) and interlanguage links.
  • The order in which categories are placed on a page is not governed by any single rule (for example, it does not need to be alphabetical, although partially alphabetical ordering can sometimes be helpful). Normally the most essential, significant categories appear first. If an article has an eponymous category (see below), then that category should be listed first of all. For example, Category:George Orwell is listed before other categories on the George Orwell page.
  • If the desired display text in a particular category is different from the title of the article, it may be appropriate to categorize a redirect, either instead of or along with the article itself. For example, if John Smith was notable as both a musician and a writer, but used the stage name Johnny Rocket in his musical career, then the musician category declarations can be placed on the "Johnny Rocket" redirect page as well as (or instead of) on "John Smith". (Redirects appear in italics in category listings.) See also Graphene Theme Documentation Wiki:Categorizing redirects.

How and when to create categories

If it has been determined (per the previous section) that a new category should be created, it should be done in overall accordance with the guide (above and below), and in harmony with existing categories.

Categories should not be created based on incidental or subjective features; other examples of types of categories that should not be created can be found at Graphene Theme Documentation Wiki:Overcategorization.

Categories follow the same general naming rules as articles; for example, common nouns are not automatically capitalized. For specific rules, see Graphene Theme Documentation Wiki:Naming conventions (categories).

To actually create a category, first add an article to the category. It will appear as a red link in the category list at the bottom of the page. Click on the red link, and add the new category to an appropriate parent category.

How to delete, merge, rename

For proposals to delete, merge, or rename categories, follow the instructions at Categories for discussion.



Many subcategories have two or more parent categories. For example, Category:British writers should be in both Category:Writers by nationality and Category:British people by occupation. When making one category a subcategory of another, ensure that the members of the first really can be expected (with possibly a few exceptions) to belong to the second also. Category chains formed by parent-child relationships should never form closed loops. If two categories are closely related but are not in a subset relation, then links between them can be included in the text of the category pages.

Diffusing large categories


Although there is no limit on the size of categories, a large category will often be broken down ("diffused") into smaller, more specific subcategories. For example, Category:Rivers of Europe is broken down by country into the subcategories Rivers of Albania, Rivers of Andorra, etc.

A category may be diffused using several coexisting schemes; for example, Category:Albums is broken down by artist, by date, by genre etc. Metacategories may be created as ways of organizing schemes of subcategories. For example, the subcategories called "Artistname albums" are not placed directly into Category:Albums, but into the metacategory Category:Albums by artist, which itself appears in Category:Albums.

It is possible for a category to be only partially diffused – some members are placed in subcategories, while others remain in the main category.

Information about how a category is diffused may be given on the category page. Categories which are intended to be fully broken down into subcategories can be marked with the {{catdiffuse}} template, which indicates that any pages which editors might add to the main category should be moved to the appropriate subcategories when sufficient information is available. (If the proper subcategory for an article does not exist yet, either create the subcategory or leave the article in the parent category for the time being.)

To suggest that a category is so large that it ought to be diffused into subcategories, you can add the {{verylarge}} template to the category page.

Non-diffusing subcategories


Not all subcategories serve the "diffusion" function described above; some are simply subsets which have some special characteristic of interest, such as Best Actor Academy Award winners as a subcategory of Film actors, Toll bridges in New York City as a subcategory of Bridges in New York City, and Musical films as a subcategory of Musicals. These are called non-diffusing subcategories. They sometimes provide an exception to the general rule that pages are not placed in both a category and its subcategory: there is no need to take pages out of the parent category purely because of their membership of a non-diffusing subcategory. (Of course, if the pages also belong to other subcategories that do cause diffusion, then they will not appear in the parent category directly.)

It is useful to identify non-diffusing subcategories with a note on the category page. The {{All included}} and {{Distinguished subcategory}} templates can be used.

Subcategories defined by ethnicity and sexuality are often non-diffusing subcategories. See also the gender, race and sexuality categorization guideline.

Eponymous categories


Often an article and a topic category will share the same name, as in George W. Bush and Category:George W. Bush, or occasionally similar names referring to the same thing, as with Mekong and Category:Mekong River. Such a category is called an eponymous category. Usually the article itself will be a member of the category (and should be sorted to appear at the start of the listing, as described below under Sort keys). A clear link to the main topic article from an eponymous category page can be created using the template {{cat main}}.

The question arises as to whether eponymous categories should be placed in (made subcategories of) the categories which their corresponding articles belong to. Logically they usually should not (for example, France belongs to Category:European countries, but Category:France does not constitute a subset of European countries). However, by convention, many categories do contain their articles' eponymous categories as subcategories, even though they are not "true" subcategories. In any case, an article should not be excluded from any set category on the grounds that its eponymous category is made a "subcategory" of that category.

If eponymous categories are categorized separately from their articles, it will be helpful to make links between the category page containing the articles and the category page containing the eponymous categories. The template {{Related category}} can be used for this. An example of this set-up is the linked categories Category:American politicians and Category:Categories named after American politicians.

Sort keys


Sort keys are sometimes needed to produce a correct ordering of member pages and subcategories on the category page. For the mechanics, see Sort order on the help page.

Because the software uses an imperfect computer sorting rather than true alphabetical ordering (see details), it is important that some sort keys be adjusted consistently. Until recently, the biggest needed adjustment was to consistently capitalize the first letter of each word and make lower case all other letters. However, the software has been improved and the largest remaining adjustment required is the replacement of non-English accented characters, such as "ź" with English counterparts, e.g. "z".

Categories of people are usually sorted by last name rather than first name, so "surname, forename" sort keys are used (as in "Washington, George"). For more information, see Ordering names in a category in the people categorization guideline.

Entries containing modified letters should be sorted as if the letters were unmodified (for example, Łódź has the sort key "Lodz").

Other sort key considerations:

  • Leading articles—a, an, and the—are one of the most common reasons for using sortkeys, moving the article to the end of the key, as in {{DEFAULTSORT:Lady, The}}. Please also apply these sort keys to deliberate misspellings of these words—e.g. "da" or "tha" for "the", as well as foreign language articles, such as "el" or "der" (but beware of non-articles that have the same spelling).
  • Spell out abbreviations and characters used in place of words so that they can be found easily in categories. E.g. the sortkey for Mr. Bean should be {{DEFAULTSORT:Mister Bean}} and Dungeons & Dragons should be sorted {{DEFAULTSORT:Dungeons And Dragons}}.
  • Entries containing numbers sometimes need special sort keys to ensure numerical rather than alphabetical ordering (for example, 19 and 103 come before 2 in alphabetical order, and IX comes before V). So Haydn's 13th symphony might have the sort key "Symphony 013", the zero ensuring that it is listed before symphonies 100–108; Pope John IX might have a sort key "John 09". It is important to stick to the same system for all similar entries in a given category.
  • Systematic sort keys are also used in other categories where the logical sort order is not alphabetical (for example, individual month articles in year categories such as Category:2004 use sort keys like "*2004-04" for April). Again, such systems must be used consistently within a category.
  • In some categories, sort keys are used to exclude prefixes that are common to all or many of the entries, or are considered unimportant (such as "List of" or "The"). For example, in Category:2004 the page 2004 in film would have the sort key "Film", and in Category:2004 in Canada the page 2004 Canadian federal budget would have the sort key "Federal Budget".
  • Use a space as the sort key for an article matching an eponymous category, or for a key article for the category. Typically, these eponymous articles or categories are best listed first even if they do not appear first in alphabetical order. For example, the article Barack Obama includes the category sort key [[Category:Barack Obama| ]]. This places the article at the start of the listing for that category. (Note: If the key article should not be a member, simply edit the category text itself to add it, perhaps using {{Cat main}}.)
  • Use other sort keys beginning with a space (or an asterisk or a plus sign) for any "List of ..." and other pages that should appear after the key article and before the main alphabetical listings. The same technique is sometimes used to bring particular subcategories to the start of the list.
  • To place entries after the main alphabetical list, use sort keys beginning with tilde ("~"). Other characters used for this purpose are "µ" (mu), used to place stub categories at the end of subcategory lists; "β" (beta) for Graphene Theme Documentation Wiki books; "Ι" (iota) for images; "Ρ" (rho) for portals; "Τ" (tau) for templates; and "Ω" (omega) for WikiProjects.
  • If a page is to be given the same sort key in all or several of its categories, the {{DEFAULTSORT}} magic word can be used. Conventionally, this is placed just before the list of category declarations. Default sort keys are sometimes defined even where they do not seem necessary—when they are the same as the page name, for example—in order to prevent other editors or automated tools from trying to infer a different default.

Content of category pages

Rather than leave the text of a category page empty (containing only parent category declarations), it is helpful – to both readers and editors – to include a description of the category, indicating what pages it contains, how they should be subcategorized, and so on. The description can also contain links to other pages, in particular to other related categories which do not appear directly as subcategories or parent categories, and to "sister categories" on other projects, such as Commons. Another technique that can be used is described at Graphene Theme Documentation Wiki:Classification.

Various templates have been developed to make it easier to produce category descriptions; see Category namespace templates. There are hatnote templates including {{Cat main}} and {{Category see also}}; others are listed at Template:Hatnote templates documentation#Categories.

A maximum of 200 category entries are displayed per screen. To make navigating large categories easier, a table of contents can be used on the category page. The following templates are some of the ways of doing this:

  • {{Category TOC}} – adds a complete table of contents (Top, 0–9, A–Z)
  • {{CatAZ}} – the same as {{Category TOC}}, but without the numbers 0–9
  • {{Large category TOC 2}} – adds a complete table of contents with five subdivisions for each letter (Aa Ae Aj Ao At)
  • {{Large category TOC}} – adds a complete table of contents with twenty-six subdivisions for each letter (Aa ... Az)

Subcategories are split alphabetically along with the articles, which means that the initial screen of a split category may not include all its subcategories. To make all subcategories display on each screen, add a category tree to the text of the category page, as described at the help page under Displaying category trees and page counts.

Interlanguage links work on category pages just as they do for articles, and can be used to link to corresponding categories on other language Graphene Theme Documentation Wikis.

Category descriptions

Sometimes, a common-sense guess based on the title of the category isn't enough to figure out whether a page should be listed in the category. For example, a category may be given a name that is relatively short and common rather than one that is precise or complete, e.g., Category:Diabetes rather than Category:Diabetes, but not including diabetes insipidus.

In such cases, the desired contents of the category should be described on the category page, similar to how the list selection criteria are described in a stand-alone list. The category description should make direct statements about the criteria by which pages should be selected for inclusion in the category. This description, not the category's name, defines the proper content of the category. Do not leave future editors to guess about what or who should be included from the title of the category. Even if the selection criteria might seem obvious to you, an explicit standard is helpful to others, especially if they are less familiar with the subject.

Non-article and maintenance categories


A distinction is made between two types of category:

  • Administration categories, intended for use by editors or by automated tools, based on features of the current state of articles, or used to categorize non-article pages.
  • Content categories, intended as part of the encyclopedia, to help readers find articles, based on features of the subjects of those articles;

Administration categories include stub categories (generally produced by stub templates), maintenance categories (often produced by tag templates such as {{cleanup}} and {{fact}}, and used for maintenance projects), WikiProject and assessment categories, and categories of pages in non-main namespaces.

Article pages should be kept out of administration categories if possible. For example, the templates that generate WikiProject and assessment categories should be placed on talk pages, not on the articles themselves. If it is unavoidable that a administration category appears on article pages (usually because it is generated by a maintenance tag that is placed on articles), then in most cases it should be made a hidden category, as described under Hiding categories below.

There are separate administration categories for different kinds of non-article page (template categories, disambiguation page categories, project page categories etc.). There is no need to categorize user pages, talk pages or redirects, although these can be placed in categories where appropriate. See the guideline on categorizing redirects, and the Categorizing user pages section below.


Whenever possible and appropriate, images should be uploaded and categorized on Wikimedia Commons. Images should be uploaded to Graphene Theme Documentation Wiki only when they are not acceptable to upload to Commons, which is the best place to categorize images.

On Graphene Theme Documentation Wiki, category tags can be added to image pages, but a category generally should not mix articles and images, a separate image category should be created or images, typically as a subcategory of the general category about the same subject, and a subcategory of the wider image category, Graphene Theme Documentation Wiki images. To categorize a new image when uploading, simply add the category tag to the upload summary.

Categorizing user pages


User pages are not articles, and thus do not belong in content categories such as Living people or Biologists. They can however be placed in user categories – subcategories of Graphene Theme Documentation Wikins, such as Graphene Theme Documentation Wikin biologists – which assist collaboration between users. See Graphene Theme Documentation Wiki:User categories for further information.

Similarly, user subpages that are draft versions of articles should be kept out of content categories. If you copy an article from mainspace to userspace and it already contains categories, remove them or comment them out. Restore the categories when you move the draft back into article space.

At Database reports/Polluted categories, a list of affected categories is maintained.

Hiding categories


In cases where, for technical reasons, administration categories appear directly on articles rather than talk pages, they should be made into hidden categories, so that they are not displayed to readers. This rule does not apply to stub categories or "uncategorized article" categories – these types are not hidden.

To hide a category, add the template {{Graphene Theme Documentation Wiki category|hidden=yes}} to the category page (the template uses the magic word __HIDDENCAT__). This also places the page in Category:Hidden categories.

A logged-in user may elect to view all hidden categories, by checking "Show hidden categories" on the "Appearance" tab of My Preferences. Notice that "hidden" parent categories are never in fact hidden on category pages (although they are listed separately).

Categorization using templates


Many templates include category declarations in their transcludable text, for the purpose of placing the pages containing those templates into specific categories. This technique is very commonly used for populating certain kinds of administration categories, including stub categories and maintenance categories.

However, it is recommended that articles should not be placed in ordinary content categories using templates in this way. There are many reasons for this: editors cannot see the category in the wikitext; removing or restructuring the category is made more difficult (partly because automated processes will not work); inappropriate articles and non-article pages may get added to the category; sort keys may be unavailable to be customised per category; ordering of categories on the page is less controllable; and the "incategory" search term will not find such pages.<ref>bugzilla:2285</ref>

When templates are used to populate administration categories, ensure that the code cannot generate nonsensical or non-existent categories, particularly when the category name depends on a parameter. Also, see Category suppression for ways of keeping inappropriate pages out of template-generated categories.

Category declarations in templates often use {{PAGENAME}} as the sort key, particularly if they are designed to be placed on talk pages, as this suppresses the Talk: prefix. Note that this overrides any DEFAULTSORT defined on the page.

Redirected categories

Because of software limitations,<ref>bugzilla:3311</ref> ordinary (hard) redirects should not be used with category pages. If a category name needs to be redirected to another, use the {{Category redirect}} template to create a soft redirect. A bot traverses categories redirected in this manner, moving articles out of the redirected category into the target category. (See Template talk:Category redirect.)

See also

For browsing

For maintenance



als:Graphene Theme Documentation Wiki:Kategorien

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