Rendered from docs/obligations/0046-the-identifier-scheme-grammar.md in the Headwater corpus. Every document on this half of the site is typed by the taxonomy the descriptor names: corpus.json.

The identifier scheme grammar

Context

The same review closed the namespace gap in place, so taxonomy validate refuses a resolved scheme that carries no namespace. core requires nothing of the kind and can require nothing of the kind. The identifier form of a core requirement names a scheme rather than a property of one. What stays open is the shape of a scheme: the prefix that discriminates the kind is a literal inside the pattern string.

Obligation

So no member of a scheme names the prefix. pattern holds it as a run of literal characters between the namespace and the local part.

Disjointness is not what this costs. Identifier integrity reads each pattern into its segments and compares the two sets of strings, which is exact. The reader is headwater_meta::identifier, and both taxonomy validate and the generated check take a pattern through it.

What the missing member costs is a name. An RDF or SKOS projection has no declared part to build a document IRI out of. The worked example derives an IRI from a repository path instead, and a rename of the file breaks every reference to it. A grammar that declares the prefix, the namespace and the local part as separate members gives that projection the parts it needs.

Discharge

A meta-schema that declares prefix, namespace and the local-part form as three members, and every scheme of the lock writing them, discharge this. The rendered form of every identifier stays as it is, which engine/crates/check/fixtures/identifiers.mint records scheme by scheme.

This record stays at current and it does not reach discharged. Half of what it asks for is met. taxonomy validate decides disjointness out of the parsed segments, so identifier integrity is decided in whole. The half that stays open is the name, and #217 tracks it.

The meta-schema has shipped at engine/crates/meta/meta-schema.yml. So the change costs a major version of the meta-schema and of the package that reads it. The cost buys a projection that nobody has asked for yet. Q13 puts each unbuilt format behind a named external consumer, and none exists. Spec 3 is where the grammar belongs.