Monolingual Text Value Type
Date: 2026-09-19
Status: Accepted
Context
A text value is a list of plain strings, so a property holding a film's original title in Basque and in Spanish cannot say which is which; no value shape carries a language. A Mapping can tag a property with lang, but that is one tag for every value of that property.
Decision
monolingualText is a Property Type, and a Value Type of its own beside string, number, boolean and relation. Its value is a list of { "text", "language" } objects.
The language is a field, not a convention inside the text. Semantic MediaWiki writes Text@en in the stored string. That needs no new value shape, but every consumer then parses the tag back out, and a text that itself ends in @en cannot be told from a tagged one.
A value, not a Subject. Text-plus-language could be a Subject linked by a relation, but it has no identity of its own, and would project as a node where a consumer of an ontology expects a literal.
A type, not an option on text. One property would otherwise hold either shape, and what tells a reader which it has — the writer's schema on the Statement (ADR 11) — records a type.
A tag is accepted on its shape: hyphen-separated subtags of one to eight characters, the primary one alphabetic. It is not checked against MediaWiki's language list, so a vocabulary using und or a script subtag is not locked out. Tags are stored lowercase, making pt-BR and pt-br one language.
A language may repeat: a thing can have two names in Spanish. uniqueItems therefore compares text and language together.
Constraints apply per part. minLength and maxLength bound each part's text, and required is satisfied by any one part. A part whose text is empty is dropped, so no part carries a language and nothing else.
A projection has to keep each part's text and language separately recoverable. RDF does so natively: one language-tagged literal per part (rdf:langString). Neo4j has neither tagged strings nor maps on properties, so a part becomes Zinema@eu, split on the last @. The in-string tag rejected above is acceptable here: a projection is rebuilt from the stored parts and never edited, so reading the tag back out is a query's job rather than a writer's.
A Mapping's lang and datatype do not reach such a value. The tag is data and differs per part, so a property-wide override could only make it less specific. lang keeps its job on a text property whose values are all in one language.
Consequences
A new value shape reaches every contract that enumerates them: the Subject JSON format, the graph model, RDF export and the Lua API.
Nothing converts values written while the property was text.
A View shows the parts in the reader's interface language, falling back along MediaWiki's language fallback chain and then to the content language, with the other parts one click away; the scalar accessors give the text without its tag.