User:Pathoschild/Wiktionary:Style guide (categories)

Naming
The category name should use sentence case— first letter capitalised, subsequent letters lowercase except for normal exceptions like proper nouns. Where relevant, category titles should be plural (for example, "Category:Animals" and not "Category:Animal").

Category page
All category pages should contain a brief explanation of the category, and be themselves categorised. Where a large number of subcategories share the same purpose with minor variations, it is possible to transclude the parent category description page with a variable. For example, see how Category:English abbreviations transcludes Category:Abbreviations with the variable "English".

Tutorial
Many templates automate categorisation; please see the section on categorisation in the relevant style guide (for example, see the style guide on dictionary entries for dictionary entry categorisation).

To include an article in a category manually, add a category tag. The list of articles on the category page will be alphabetized in the strict Unicode order of the titles unless you dictate otherwise. One effect of this is that all English articles beginning with a capital letter will be listed before any that begins with a lower case letter, which is not desireable. You can fix this problem with a piped link; placing on Aspirin will categorise it under a instead of A.

Placement
Categories should be placed in alphabetical order at the bottom of the edit box, above any interwiki links. The exception is discussion pages; categories should be placed at the top so users don't accidentally post new comments below them. Placing these tags consistently simplifies maintenance and editing.