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Reference Resolution

The /ref endpoint accepts an external reference in its single reference query parameter, auto-detects which reference method it is, and resolves it — redirecting either to a CPRMV API /rules/ path or to an external source.

This allows other systems that produce Juriconnect, ELI, or CPRMV-API references to pass them directly without needing to understand the internal ID format.

How detection works

The endpoint takes no method in its path: the call is simply GET /ref?reference=…. The reference methods acknowledged in cprmvmethods:referencemethods are tried in order — cprmvapi, juriconnect, elifmx4, elinl — and the first whose method module returns a target wins. Each is a class in serve_api/methods/ (cprmvapi.py, juriconnect.py, and eli.py for both ELI methods). A successful match answers with a 307 Temporary Redirect.

Juriconnect

Both jci1.3 and jci1.31 versions are supported. The reference format is jci1.{subversion}:c:BWB{bwbid}&{locatie-string}.

Supported locatie types: the locatie-string keys are mapped to rule identifiers by cprmv-serve:reference-mapping (for example artikel → Artikel, o → onderdeel, lid → lid, hoofdstuk → Hoofdstuk, paragraaf → Paragraaf). Whether a mapped rule can be found depends on the BWB XSLT transform; the endpoint description names artikel, hoofdstuk, paragraaf, onderdeel and lid as supported.

Example reference:

GET /ref?reference=jci1.31:c:BWBR0015703&artikel=20&o=a.

redirects to /rules/BWBR0015703_{today}_latest%2CArtikel%2020%2Conderdeel%20a..

The valid-on date (g / geldig-op) becomes the date of the rule set id and the version valid on that date is looked up; when absent the date defaults to today, with index latest.

The sighting date (z / gezien-op) is not ignored: its value is placed in the version-index position of the rule set id instead of latest. …&g=2025-07-01&z=2025-07-01&artikel=20 therefore resolves to BWBR0015703_2025-07-01_2025-07-01, which skips the SRU lookup. Whether this is intended is asked in standards/cprmv#31.

Limitations:

  • Only single-consolidation references are supported; multi-consolidation (mconsolidatie) is not.
  • The full set of locatie types supported by the Juriconnect standard may not all be implemented in the BWB XSLT transform.
  • The part of the BWB id after BWB must be exactly 8 characters — BWBR0015703 (R0015703) qualifies; the module upper-cases it.
  • A malformed Juriconnect reference (a wrong version, a too-short BWB id, or a locatie-string part without =) is not recognised by the module and falls through to the ELI → CELLAR method, whose query fails on it: the endpoint answers 500 Internal Server Error.

ELI → Formex 4 on EU CELLAR

Implemented by elifmx4.transform_reference in eli.py. The method queries the EU CELLAR SPARQL endpoint for the manifestation item matching the ELI work and redirects to the first item found. Language and format are fixed to NLD and fmx4.

Example:

GET /ref?reference=http://data.europa.eu/eli/reg/2018/1805/oj

redirects to http://publications.europa.eu/resource/cellar/83e4752e-f2e5-11e8-9982-01aa75ed71a1.0017.02/DOC_1.

Because this method queries CELLAR for any reference that reaches it, every reference not handled by cprmvapi or juriconnect costs a CELLAR round trip before elinl is tried.

See also the /cellar-by-eli endpoint for explicit language/format control.

ELI for BWB and CVDR (experimental)

A forward-slash-delimited path after https://wetten.overheid.nl/ is mapped to a CPRMV API /rules/ path (method elinl, reference format https://wetten.overheid.nl/{path}).

Example:

GET /ref?reference=https://wetten.overheid.nl/BWBR0015703/Artikel%2020/onderdeel%20a.

CPRMV API rule id path

A /rules/ URL (on this or another CPRMV API instance) is accepted and re-issued against this instance (method cprmvapi, reference format {baseuri}/rules/{path}); slashes in the path become comma separators.

Example:

GET /ref?reference=https://cprmv.open-regels.nl/rules/BWBR0015703/Artikel%2020/onderdeel%20a.

Reference method configuration

The supported reference methods are acknowledged in the cprmvmethods:referencemethods list in data/cprmvmethods.ttl. Each method node carries its own configuration:

  • cprmv-serve:reference-format — the parse pattern the reference must match.
  • cprmv-serve:reference-mapping (Juriconnect) — a list of key–value pairs that translate locatie-string keys to CPRMV rule ID path segment labels, plus two special entries:
    • cprmv-serve:reference-mapping-valid-on — the locatie-string key that carries the valid-on date (g).
    • cprmv-serve:reference-mapping-seen-on — the locatie-string key for the sighting date (z).

cprmv-serve: is the namespace https://cprmv.open-regels.nl/0.4.2/serve-api/.

If no method matches, the endpoint returns {"error": "not a valid or supported reference..."}.