(This change is relevant for all Wikidata users working with labels, descriptions, and aliases.)
Based on a long-standing community request we have enabled a new language code for labels, descriptions, and aliases on Test Wikidata: “mul”, a special language code meaning “multiple languages”. It is intended to replace the current duplication of certain labels and aliases in many languages: instead of the given name Douglas (Q463035) having the label “Douglas” in hundreds of Latin-script languages, it should be enough to add it once as the “mul” label and have all other languages falling back to that (before, as usual, falling back to “en” as a last resort). This should reduce the amount of redundant data in Wikidata, and relieve some pressure from the query service. A big thank you goes to all people involved in the discussions!
The purpose of the Test Wikidata version of this feature is to determine whether the current functionality is already sufficient, or whether the feature needs more work before it can be enabled on Wikidata proper.
You can interact with the new language code using the API.
The new language code appears in the table of labels at the top of an item page for users whose Babel information includes “mul” (or who use ?uselang=mul in the URL). If there is already a “mul” label, it will be available for everyone under the usual “all entered languages” option.
The page heading will fall back to the “mul” label if necessary. Fallbacks to “mul” have the usual “indicator” that shows a fallback took place (CSS class wb-language-fallback-mul).
For more details, see T285156 (or T297393 for the Test Wikidata implementation). You are welcome to leave any feedback about the technical implementation of the new language code on these tickets.
The new language code will very likely need adjustment of Wikidata policies and guidelines. In case you would like to contribute to drafting preliminary new guidelines, a good starting point is: Help talk:Label#Drafting of guidelines for new language code mul.