Cross-register mappings

A cross-register mapping is a registered item (class cross-register-mapping) that states a correspondence between identifiers or semantics in two registers — for example, that a Chinese national standard corresponds to an IEC standard for the purposes of some conformity evidence. Mappings are versioned, dated, and integrity-checked like every other registry item; they are how peers and foreign registers reconcile without merging.

The registry endpoints

The mapping class has a subregister surface (/cross-register-mappings) and dedicated queries:

Endpoint	What
GET /cross-register-mappings?item=&source=&target=&register=&at=	mappings by item, source register, target register
GET /cross-register-mappings/{id}	one mapping
POST /items (class cross-register-mapping)	register a mapping
GET /cross-register-mappings/{id}/supersession	the mapping’s version chain

The worked example (recorded)

The pilot’s seeded mapping — GB 4943.1-2022 ↔ IEC 62368-1 for charger conformity evidence:

$ curl -s 'http://127.0.0.1:8390/cross-register-mappings?limit=2' \
    | jq '.items[0] | {identifier, title, version: .version.status, effective: .version.effective_from}'
{
  "identifier": "urn:unidpp:map:gb4943-iec62368",
  "title": "GB 4943.1-2022 corresponds to IEC 62368-1 for the purposes of charger conformity evidence",
  "version": "valid",
  "effective": "2026-09-01T00:00:00Z"
}

Note the shape of the claim: not “GB 4943.1 = IEC 62368-1” (two standards are never identical), but a scoped correspondence — for the purposes of — with a version and an effective date. A mapping is a legal fact, and it is dated like one.

Integrity checks

Mapping intake is one of the registry’s three named intake checks (alongside the profile-manifest schema and profile satisfiability): the referenced items, source and target registers must resolve. A mapping to a nonexistent item is rejected at registration, not discovered at query time.

Why mappings are global

A mapping’s value is that both sides trust it. A jurisdiction’s register can hold its own mappings, but the mappings between external registers — GB ↔ IEC, or a jurisdiction profile ↔ a sector profile — belong in the global register where every peer can resolve them. This is the split the JP peer page summarizes: the global node keeps what is governance-shaped; jurisdiction-shaped data lives with the jurisdiction.

What mappings are not

• Not transforms. The transform class (/transforms) is executable semantics — unit conversions, classifications, code-list mappings a projector view runs. A mapping is a registered claim about correspondence; a transform is a function. (The GB↔IEC item doubles as a transform in the pilot’s seed corpus, which is why its submitting organization names the equivalence seed.)
• Not identifier resolution. Resolving one identifier to another is the resolver’s job; mappings state why two identifiers correspond.