Workgroup:Categories/guidelines

See Help:Category for the what, why and how of categories, including a quick summary.

Categorization is a feature of the MediaWiki software, enabling pages to be placed in categories which can then be used to find collections of resources on related topics. Categories can be defined as subcategories of other categories, facilitating navigation between connected subject areas. This helps readers find resources on particular topics even if they don't know which resources exist or what they are called. The term category is used in a number of related ways:
 * Category: a collection of WikiEducator pages
 * Category page: a page listing all members of a category; a member of the Category: namespace
 * Category member: a page (either a main page or category page) containing a link of the form [[Category:X]]
 * Subcategory: a category that is a member of another category; also called a child category
 * Parent category: a category containing a collection of one or more other categories
 * Category: namespace: the collection of pages beginning with "Category:"

=30-second summary= Including Category:Name in the text of any editable page causes that page to be placed in a category called "Name". This link will not show up where it appears in the text, but a corresponding link will appear in the "Categories" box at the bottom of the page. The target of this link is a page called "Category:Name" – the link will be red until such a page is created. Conventionally, these category declarations are placed at the end of the page text.

The category page is itself a normal editable page, but has a special mode of display – it lists all the pages that have been placed in the category it represents. If any of these pages is itself a category page, then it is treated as a subcategory; these are listed first. Otherwise it is treated as a member page of the category; these are listed below the subcategories. Any ordinary page content appearing in the text of the category page is displayed before the lists of subcategories and member pages. For further details about category pages, including sort order, see Display of category pages below.

To make a normal link to a category page from another page, precede the word "Category" with a colon, as in Category:Mathematics, which appears as Category:Mathematics. These links do not put the page in the category, and can be piped like ordinary wikilinks.

Vision for WikiEducator category structure
"WE's category structure is a bit out of shape at the moment. For example, about 30% of the categories used don't actually exist, yet; there are a handful of central/root/contents categories, none of which go deeper than a few levels; there are (as I write this) 12,200 uncategorised pages out of 68,992 total, or about 15%; and most of the existing categories aren't connected to any other category."
 * --Jesse Groppi in a post to the WikiEducator google group on 12 Oct 2009

WE envision a category system that functions as a hierarchical structure of multiple, interconnected trees, with each category having a direct path branching to the root (top) category. Category:Contents is suggested as the sole root category.

WE envision a few types of categories, noting that there are likely some that are combinations of these:

Topic categories tend to be written in the singular, and include resources related to the topic. Each member page is a resource related to that subject. Example: Category:OER includes subcategories and pages about the creation or use of OER, not actual OER resources, which, if created, would include all of the resources on WikiEducator.

List categories tend to be written as plural, and include resources that are an instance of the subject described in the category name. Example:

Resource categories describe a multi-page project, node, or learning resource and include all of the related pages, often subpages of the main page, e.g., ....

If the member resources of one category page belong logically to to a second, the first is made a subcategory of the second. A category page is subcategorized when a category declaration is placed in it. The category  belongs to the category . For the   category to appear in the   category, the page makes the category declaration

A page need not be added explicitly to all of the categories that logically contain it: normally a page (or subcategory) would not be added explicitly to a category if it is contained in one of that category's subcategories. However, there are quite common exceptions to this.

Categorisation using templates
Some notes to feed our thinking on this topic....

From Wikipedia's guidelines on categorisation 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 project 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; ordering of categories on the page is less controllable; and the "incategory" search term will not find such pages.

When templates are used to populate project 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 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.

Some thoughts on what to include in these guidelines

 * Categories overview - what they are, why -- first draft, --Alison Snieckus 20:31, 24 January 2010 (UTC)
 * How to's
 * categorisation of subpages
 * categorisation of user subpages
 * use of sort lists to organise listing of entries in the category
 * categorisation of adapted resource
 * overcategorisation
 * adding new categories and subcategories
 * use of Template:OER_Metadata for categorization
 * Care and feeding of categories map and guidelines
 * workgroup
 * structure map
 * add new categories
 * revise existing
 * retire unused
 * revise existing
 * retire unused

Information about this resource
Some of the sections included in these guidelines are adapted from Wikipedia's Wikipedia:Categorization page.