User:DexDor/Categories

Introduction

The following notes have been made in attempt to understand how categories currently work in WP and how the guidance (e.g. WP:DEFINING) can be improved. Comments (e.g. on the talk page) are welcome.

I've been thinking about how WP:DEFINING can be improved for a while. A good step would be to separate the guidance for categorization of articles about individual (unique) things and that for articles about concepts as IMO trying to have one sentence that covers both is the main reason why WP:DEFINING is currently so meaningless/ambiguous. Maybe something like:

Articles about individual people and (unique) items (John Smith, BBC, RMS Titanic ...) should be categorized by the characteristic(s) that makes the person/item notable (e.g. a person may be notable as an actor) and by biographical characteristics (in particular the year of birth/establishment/construction). Articles about other subjects (e.g. concepts) should be categorized by what the subject is a subset of - for example the subject of warships is part of the subjects of naval warfare and ships.

Most WP articles are already categorized as per the above guidance. Many articles also have other categories (e.g. "alumni of"); the above guidance could be extended to allow such categorization where it would not cause lots of categories to be added to an article (see [1] for an example of what we don't want).

For some articles a blend of the two aspects of this guidance could be used - e.g. not every Supermarine Spitfire was a fighter aircraft (some were unarmed), but the Spitfire achieved notability as a fighter so its article can be categorized as such.

That a rule is often broken is not a good reason to rescind the rule. An analogy: in the UK the speed limit on motorways is 70mph, but many drivers sometimes (marginally) exceed it. If the limit was increased to 80mph some drivers would exceed that ...

Types of categories

This is a list of (some of) the types of categories that WP categorization guidance refers to. This list has been drawn up in attempt to see if any simplifications can be made and/or to avoid other types being defined.

Terms used to describe categories in Wikipedia
Definition and example quote(s) using the term	Notes
An administration category (or project category) is a category that contains pages that are not articles, or it groups articles by status rather than content. Administration categories should not be in content categories. These categories are used mainly by Wikipedia's editors, rather than for browsing. Examples of administration categories include Category:Wikipedia backlog and stub categories. Administration categories or project categories [are] categories used mainly by Wikipedia's editors for project management purposes, rather than for browsing. Category:Wikipedia backlog links to many categories with articles that need to be worked on, sorted by reasons. Another common category is the stub category... ^{(Wikipedia:FAQ/Categories)}	??
A birth/death/living category - (e.g. on CAT:NOCAT) xxx ^(yyy)	??
A category category is a category containing categories that are not subcategories. (see Template:Category_header) xxx ^(yyy)	??
A container category is a category that contains (or is intended to contain) only subcategories rather than articles. (from Wikipedia:Container category) xxx ^(yyy)	??
A content category is a category that contains encyclopaedic contents. (from Template:Category_header) (e.g. on CAT:NOCAT) xxx ^(yyy)	??
A disambiguation category is a soft redirect to 2 or more categories. Example: Category:Bayside Subcategories of this category should not contain any members. Instead, they serve to inform editors of the titles of similarly-named categories where things should go instead, analogous to disambiguation pages for articles. ^{(Category:Disambiguation categories)}	This should not be confused with categories for disambiguation pages. There is a reference to this from Template:Db-c1.
A distinguished subcategory - see non-diffusing subcategory xxx ^(yyy)	??
An eponymous category is a category which covers the exact same topic as an article. (WP:EPON) xxx ^(yyy)	??
A hidden category is ???? (e.g. on CAT:NOCAT) xxx ^(yyy)	??
A holding category is ??? (e.g. in the text of Category:National Register of Historic Places articles needing infoboxes) xxx ^(yyy)	This CFD deleted a holding category.
An intermediate category is a category used to organize large classes of subcategories, such as Category:Albums by artist.^{(Wikipedia:FAQ/Categories)} xxx ^(yyy)	??
An intersection category is ??? Many categories are in essence the intersection of two or more larger categories. For example, Category:American film directors can be thought of as the intersection of Category:Film directors and Category:American people. There are many intersection categories that do not exist that some people might find useful. ^(WP:CATI)	??
A maintenance category is ???? This is a maintenance category. It is used for maintenance of the Wikipedia project and is not part of the encyclopedia. It contains pages that are not articles, or it groups articles by status rather than content. Do not include this category in content categories. ^{(Template:Wikipedia category)}	Maintenance categories are temporary categories.???
A navigational category is ??? A navigational category is a category which contains subdirectories. An example of this is Category:American people by occupation. Navigational categories should not contain any articles. ^(WP:CATI)	In the quoted text the last sentence should have "directly" added.
A nationality/occupation category is ???? (e.g. on CAT:NOCAT) xxx ^(yyy)	??
A non-diffusing subcategory (aka distinguished subcategory) of a category includes articles that can also be found in the parent category. (Template:Distinguished subcategory, WP:DUPCAT) xxx ^(yyy)	??
A parent-only category is TBD. This stub category is a parent-only category, that is, all stubs within it should be in one of its subcategories, or marked with a template which may eventually have a separate subcategory. To add an article to this category, please use the appropriate template for one of its subcategories. ^{(Template:Parent-only stub category)}	??
A permanent category is any category other than a temporary category (e.g. on CAT:NOCAT) xxx ^(yyy)	??
A primary category or primary (topic level) category is ???? (from Wikipedia:Category_intersection) xxx ^(yyy)	??
A project category (see administration category) xxx ^(yyy)	??
A polluted category is TBD - Wikipedia:Database reports/Polluted categories xxx ^(yyy)	??
A redlinked category is ????. An article is also not properly categorized if it contains redlinked categories which don't actually exist; either find or create an appropriate category, as articles cannot be left sitting in redlinked categories. ^(CAT:NOCAT)	??
A subcategory is ????. (WP:SUBCAT) xxx ^(yyy)	??
A set category is a category of articles on subjects in a particular class, such as Category:Villages in Poland.^{(Wikipedia:FAQ/Categories)} xxx ^(yyy)	??
A set-and-topic category is a category that is a combination of a set category and topic category.^{(Wikipedia:FAQ/Categories)} xxx ^(yyy)	??
A stub category is ?????. Stub categories are temporary categories. (e.g. on CAT:NOCAT) [A common administration] category is the stub category, which contains very short ("stub") articles that need expansion. Wikipedia:WikiProject Stub sorting/Stub types contains a giant list of stubs, sorted by topic.^{(Wikipedia:FAQ/Categories)}	??
A temporary category is ????. Examples include stub categories and maintenance categories. Stub and maintenance categories are considered only "temporary" categories; stubbed articles should be included in permanent categories as soon as possible. An article is not considered to be properly categorized if it does not have at least one permanent content category on it. An article is also not properly categorized if it contains redlinked categories which don't actually exist; either find or create an appropriate category, as articles cannot be left sitting in redlinked categories.^(CAT:NOCAT)	This doesn't mean that the category itself is temporary.
A topic category is a category of articles relating to a particular topic, such as Category:Geography or Category:Paris.^{(Wikipedia:FAQ/Categories)} (e.g. on WP:CAT) xxx ^(yyy)	??
A tracking category is a category intended to build and maintain a list of pages primarily for the sake of the list itself (see Template:Tracking category) xxx ^(yyy)	??
A universal category is a category used to provide a complete list of articles which are otherwise normally divided into subcategories. Universal categories – categories used to provide a complete list of articles which are otherwise normally divided into subcategories. ^{(Wikipedia:FAQ/Categories)}	This term is (as of 2016) very little used. Perhaps it should be removed from the FAQ page.
A wanted category isn't actually a category .... - see Special:WantedCategories xxx ^(yyy)	??
A Wikipedia category is a category needed for Wikipedia administrative purposes, but that is not part of the encyclopedia itself. (Template:Wikipedia category) xxx ^(yyy)	??
A work category is TBD. All categories that start with "Wikipedia" in the name are work categories. ^{(Category:Wikipedia maps)}	The quoted text isn't entirely correct - e.g. see Category:Wikipedia and some of its subcategories.

Wikipedia:Database_reports

Year of birth/death categories

"Normal" categories group together articles about similar topics (e.g. 19th century French painters) which can be of use to readers/editors. When such categories get large there's usually some way in which they can be split to make them more useful. The year-of-birth/death categories don't group together such similar articles, but they may be useful (e.g. for editors maintaining BLP tags) and they have low cost - e.g. they cause little watchlist noise (typically they only need to be edited when the article is created and when the person dies) and they don't cause much category clutter. Hybrid categories would have the costs without (afaics) providing much (if any) benefits. Examples of CFDs discussing hybrid categories: Wikipedia:Categories_for_discussion/Log/2017_May_28#Category:Racing_drivers_born_in_YYYY, Wikipedia:Categories_for_discussion/Log/2017_May_30#Deaths_of_Greek_people_by_year.

Reference is often made to these categories at CFD by editors who appear to be unaware that these categories are used differently to normal categories.

Should these categories be considered as maintenance categories?

Question: Do these categories therefore count as maintenance categories (e.g. should they be hidden from readers) ?

Making these categories hidden would have several advantages -

It would prevent readers opening a category page that is unlikely to be any use for navigation (because of the 10s of thousands of articles in it) and may confuse them about how categories are intended to be used.
It would reduce the frequency of editors failing to distinguish these from normal article cstegories - e.g. In CFD duscussions or by creating subcats.
It would make it easier to find pages that are only categorized by yob/yod/lp (e.g. using tools.wmflabs.org/dplbot/cat/uncategorized_pages.php). Such pages are unlikely to have been found by a wikiproject. There may be other ways (e.g. using AWB) of finding such pages.

However, editors may argue that the year of birth (for example) is a characteristic of the person (the subject of the article) and that hidden categories should only be for characteristics of the article itself (e.g. being unreferenced).

Checking categories

How many (if any) of these should be categorized under Category:Articles ?

Redirect categories - see WP:RCAT.
Portals and Portal categories [2]
Disambiguation pages - see WP:DBC. [3]
Category:Wikipedia requested photographs of mythology subjects etc
WikiProjects
Templates - see WP:CAT#T. Note: there are at least 3 other ways of getting to a template (template categories, talk page categories, from article that uses template). [4]
Talk pages
Stub categories
Categories like Category:Wikipedia articles incorporating text from the United States National Library of Medicine

Understanding WP:DEFINING

Proposal A

There are 3 types of characteristics that a subject can have that determine what Wikipedia categories a Wikipedia article about that subject should be in:

1. The subject is completely within another (more general) subject. E.g. the subject of Political history is a subset of the subject of History. The title of the subject normally makes clear what subjects it is a subset of.

2. The subject is notable with respect to another subject (e.g. a person may be a notable politician or artist). This applies mainly, but not exclusively, where the subject is an individual person. In a Wikipedia article the notable characteristics are normally found in the lead of the article.

3. "Biographical" characteristics (year of birth, nationality etc). This applies to people, but also to individual animals, organisations (e.g. year of establishment of a company) etc. In a Wikipedia article this information is often in the lead and/or in an infobox.

These 3 types of characteristics can sometimes overlap.

A Wikipedia category is for articles that have one or more (i.e. an intersection) of these characteristics.

In addition there are Wikipedia administration categories. Many of these are hidden from readers.

Proposal B

Articles about specific named things (e.g. individual people) are categorised based on two types of characteristics - characteristics based on the reason(s) for notability (e.g. being a famous actor) and biographical characteristics (year of birth, nationality etc). Articles about individual organisations, individual buildings, individual animals, specific types of aircraft etc are similarly categorised both by reason for notability and for "biographical" information (e.g. year of establishment of a company). For a few categories it may not be clear from the category name which of these 2 kinds of characteristic it is based on (e.g. Category:People with cancer, Category:Murder victims).

Articles about concepts are categorised based on what the concept is a subset of. For example the Political history article is in Category:History and Category:Politics.

Many categories are for articles that have a combination of characteristics (e.g. Category:British fighter aircraft 1930–1939 is the intersection of Category:Fighter aircraft 1930–1939 and Category:British fighter aircraft).

In addition there are Wikipedia administration categories, many of which are hidden from readers.

Projects

Category:Terminology

In November 2011 there were over 600 articles in the "Aviation terminology" category. Not one of these articles was actually about terminology (a subset of linguistics). Having an article inappropriately in a terminology category is not itself much of a problem, but there were about 100 aviation articles that weren't in any other aviation category - for example anyone looking in Category:Types of take-off and landing would not have found the article about Brodie landing system. Each article in the "Aviation terminology" category was examined and categorised more appropriately (e.g. into Category:Aircraft navigation) or deleted (e.g. by replacing with a redirect or PRODing).

Putting an article in a terminology category because the article title is a term is an easy mistake to make (I've done it myself in the past) although in many cases (Bay of Bengal Cooperative Air Traffic Flow Management System, Aviation Maintenance Technician Day etc) even the title isn't really a term.

If an article really is about terminology (i.e. terminology is a defining characteristic of the article's subject) then, of course, it should stay in the Terminology category. Sometimes (e.g. Medical terminology) this should be in addition to a subject-based category. Wikipedia is supposed to be about subjects, not words (Cf Wiktionary), therefore the categorisation should be based on the subject of the article, not whether the article title is an acronym, terminology, phrase, name etc.

It has been suggested (e.g. Wikipedia:Stub types for deletion/Log/2011/May) that Terminology categories provide a useful way to separate articles about specific subjects (i.e. where the article title is a name e.g. Air France) from articles about generic subjects (e.g. Airline ticket). It may be useful to separate articles about specific and generic subjects, but terminology categories are not the best way to do this; normal WP practice is to put articles about specific aircraft (for example) in categories such as "... by country" and "... by decade".

Award recipients

Species

Species by country

Example CFD discussions:

Reasons that have been proposed to keep (i.e. to not upmerge) these categories:

These categories should be converted into endemic categories. ("several of the "fish of X" categories ... could have survived on their own merits if even just restricted to endemics") (CFD of 29/8/2014)

Upmerging would make the parent category overpopulated.

These categories would be OK if used correctly. ("If correctly implemented and not abused, country categories nested inside regional categories nested inside continent categories can achieve the goal of reducing category clutter.")

One of these CFDs closed as NC. ("Note that a previous discussion on a "Birds of Country" resulted in no consensus.") (CFD of 29/8/2014)

A species' distribution is defining. ("... whether a species' distribution is defining. I contend it is defining ...") (CFD of 29/8/2014)

Volga

WP:OTHERSTUFF

The CFD nomination is too long. ("Categories that are nominated for deletion ... using a wp:wall of text as rationale should never be deleted.") (CFD)

Deaths by cause

Some discussions:

Related discussions:

Wikipedia_talk:WikiProject_Biography/Archive_50#Categorising_by_place_of_burial

My position:

Biographical articles (i.e. articles in Category:Births by year) should not be categorized by cause of death. The purpose of wp categorization is to categorize wp pages, not to be a database of biographical data (cf. WikiData). For most people with wp articles (sportspeople, actors, politicians etc) their cause of death is not directly related to their notability. Some particular reasons why these categories are bad:

They cause incorrect categorization (e.g. placing someone in Category:Medicine because the person died of a medical condition).
They cause category clutter (making it harder to use more relevant categories). There are often as 5 or more c-o-d category tags on a page (suicides in Fooville, firearm deaths in Fooville, actors who committed suicide ...). E.g. Adolf Hitler has 6 "suicide" categories.
They can lead editors down a route of thinking that as many biographical characteristics as possible should be categorized (descent, burial etc).
They cause watchlist noise.

In some cases it's appropriate to restructure a page from "John Smith" to "Murder of John Smith" (if the person isn't wiki-notable, but the crime is).

Solutions:

Have something at WP:COP (similar to WP:COP#N).

Common objections:

Category:1900 births ...

Examples of difficult cases:

Christopher McCandless - it probably isn't appropriate to turn his article into "Death of Christopher McCandless". This may be a case where a redirect at "Death of..." might be appropriate to go in a category.

People by descent

Example discussions:

Wikipedia:Categories_for_discussion/Log/2015_May_20#People_of_X_descent - keep

An interesting thing about descent categories is how many editors involved in the creation or population of such categories have been blocked (although this may be for totally unrelated reasons).

Special:Contributions/Bossanoven e.g. edits like this[5]
Special:Contributions/Dogfacebob

One editor appears to have been adding ethnicity categories based solely on surnames.^[1] A similar case is fixed by this edit.

Some examples of very specific descent categories:

Category:British people of Levantine-Greek Orthodox Christian descent (related CFDs)
Category:Canadian people of Ulster-Scottish descent

Example of lots of descent etc cats: [6] [7] (added 6 descent categories), Alicia Keys (in 6 descent cats as of Feb 2016).

Example of descent categories being added for no/incorrect reasons: [8]

An example descent CFD is Wikipedia:Categories_for_discussion/Log/2015_December_2#Category:Lebanese_people_of_Maronite_Christian_descent.

References

^ User_talk:Bossanoven/Archive_6#Surnames

Military vehicle types - current categorization

This shows only some of the categories (as of August 2013). Italic font indicates where changes to the category structure are proposed. This does not necessarily list categories in alphabetical order.

 Category:Military vehicles (by country, by period)
   Category:Military vehicles by type (tracked, wheeled)
     Category:Military ambulances 
     Category:Artillery tractors   
     Category:Command vehicles
     Category:Military engineering vehicles
       Category:Armoured vehicle-launched bridges
     Category:Military light utility vehicles
     Category:Military recovery vehicles
       Category:Armoured recovery vehicles (by country, tracked, wheeled)
     Category:Reconnaissance vehicles (by country, tracked, wheeled)
     Category:Soft-skinned vehicles
     Category:Military trucks (by country)
       Category:Tank transporters
     Category:Combat vehicles (by country, airborne)
       Category:Combat vehicles by type
         Category:Armoured fighting vehicles (by country, by period, amphib)
           Category:Armoured fighting vehicles by type
             Category:Armoured cars (by country, by period)   
             Category:Self-propelled anti-aircraft weapons  
             Category:Armoured personnel carriers (by country, by period, amphib, tracked, wheeled)
             Category:Armoured recovery vehicles (tracked, wheeled) 
             Category:Tank destroyers (by country, by period)
             Category:Infantry fighting vehicles (by country, by period, amphib, tracked, wheeled)
             Category:Tankettes (by country, by period)
             Category:Internal security vehicles
             Category:Tanks (by country, by period, by period by country)
               Category:Tanks by type (amphib, airborne)
                 Category:Cavalry tanks  
                 Category:Cruiser tanks
                 Category:Flame tanks
                 Category:Heavy tanks
                 Category:Infantry tanks
                 Category:Light tanks
                 Category:Main battle tanks
                 Category:Medium tanks
                 Category:Multi-turreted tanks
                 Category:Superheavy tanks
                 Category:Tanks with autoloaders  
         Category:Fire support vehicles       
         Category:Self-propelled artillery (by country)
           Category:Assault guns
           Category:Mortar carriers (tracked)
           Category:Self-propelled howitzers (tracked, wheeled)
           Category:Self-propelled rocket launchers (tracked, wheeled)
       Category:Unmanned ground combat vehicles

Categories with non-permanent membership

Some examples of mainspace categories whose membership is not permanent:

"Category:Current FBI Ten Most Wanted Fugitives" (has been deleted several times)
Category:Insurgencies currently ongoing
Category:Active ships (and all its subcats)

Categories where corresponding article is a dab page

Sortkey

Stubs

Currently (August 2014) we have two separate category trees for stub articles -

A category tree based on stub tags placed on article pages. This places articles in Category:Stub categories (and subcategories).
A category tree based on wikiproject quality assessment tags placed on article talk pages - i.e. categorizing an article as being stub class. This places article talk pages in Category:Stub-Class articles (and subcategories).

So, for example, we have both Category:Airport stubs and Category:Stub-Class airport articles. This, IMO, is an unnecessary complication in Wikipedia - in checking categorization I've found several cases where an article-side stub category was placed in a wikiproject category (example) or a talk page stub category was placed in an article-side stub category (example). Note: Any overlaps between these two category trees can be detectd by this check. It may be useful for readers to be "warned" that they are looking at a stub article, but there is no reason why a reader (i.e. a person looking for a piece of information) would want to navigate specifically to stub articles. Editors don't need 2 ways of finding stubs on a particular topic. Stub categories cause many discussions at CFD (e.g. i n J u l y 2 0 1 4), partly because stub categories are continually adding/losing articles.

Possible way ahead:

Ensure that there are cross-links between the article-side stub categories and editor-side stub categories.
Hide the stub categories (but see Category_talk:Stubs#Proposal:_Stub_categories_should_be_hidden) - note: the template (including any picture) would still be shown.
CFD the article-side categories for upmerging (mostly via change to template).
Remove stub categories from under Category:Articles.
Remove stub category from WikiProject Stub Sorting - that places all the articles under a wikiproject which is wrong, or at least inconsistent with the rest of Wikipedia (in which project cats contain talk pages, but not articles themselves) - after ensuring there's a clear link from (what was) parent.

See Wikipedia:WikiProject Stub sorting.

I suggest we change the article-side stub templates to place articles in a single category - then delete the empty categories. Note: It's also possible for editors to look at the what-links-here list for a stub template.

Another complication regarding (reader-side) stub categories is that when a category is renamed (e.g. from Category:American broadcasting to Category:Broadcasting in the United States) a subcategory for stubs (e.g. Category:United States broadcasting stubs) isn't automatically moved (by bot) to the new category (presumably because the categorization is controlled by a parameter of Template:Stub Category rather than an actual category tag).

Loops

Copied from User:Danilo.mac/Category loops in Jan 2015

List of first 200 of the 2571 category loops in Wikipedia.

In a book about World War II it would be reasonable to have a chapter titled something like "Aftermath of World War II" (including things that have a varying link to WWII) - and that might have a paragraph on the Cold War. On that basis, the Cold War might be considered a subtopic of WWII. However, similar logic would place ... ... librarian?