generated: '2026-07-26'
method: derived
source: openapi/landgate-slip-public-arcgis-openapi.yml, openapi/landgate-data-wa-ckan-openapi.yml,
  openapi/landgate-slip-public-ogc-openapi.yml, plus live probes 2026-07-26
note: |
  Landgate publishes no API design guide, no developer portal and no conventions page. Every
  convention below is derived from the behaviour of the three public surfaces as observed
  live, or from the upstream product standard those surfaces implement (Esri ArcGIS REST,
  OGC WMS/WFS, CKAN Action API). Where a convention does not exist, it is recorded as absent
  rather than guessed.
authentication:
  style: none on the public tier; OAuth 2.0 / OIDC on the gated MyLandgate tier
  detail: authentication/landgate-authentication.yml
idempotency:
  supported: false
  note: |
    No idempotency contract exists. All three public surfaces are read-only GET surfaces —
    there is no write operation to make idempotent, no Idempotency-Key header is documented
    or accepted, and no such parameter appears in any harvested contract. Do NOT wire an
    Idempotency pointer for this provider.
pagination:
  - surface: SLIP ArcGIS REST feature query
    style: offset
    params: [resultOffset, resultRecordCount]
    response_fields: [exceededTransferLimit, features]
    limits:
      maxRecordCount: 10000
    evidence: probed 2026-07-26 — SLIP_Public_Services/Boundaries/MapServer reports
      maxRecordCount 10000; returnCountOnly=true on layer 14 returned {"count":139}
  - surface: Data WA CKAN Action API
    style: offset
    params: [rows, start]
    response_fields: [count, results]
    limits:
      default_rows: 10
      max_rows: 1000
    evidence: CKAN help_show?name=package_search documents rows default 10, upper limit 1000
  - surface: SLIP OGC WFS 2.0.0
    style: index
    params: [count, startIndex]
    caution: |
      A GetFeature with count=1 against esri:DFES_Regions__DFES-015_ returned a 1.65 MB GML
      FeatureCollection on 2026-07-26 — server-side limiting should not be assumed on this
      deployment. Filter with bbox or a CQL/OGC filter instead of relying on count.
filtering:
  - surface: SLIP ArcGIS REST
    params: [where, geometry, geometryType, inSR, outSR, outFields, returnGeometry]
    note: SQL-style `where` clause plus spatial geometry filters.
  - surface: Data WA CKAN
    params: [q, fq, sort, facet.field]
    note: Solr query surface. `fq=organization:landgate` narrows the 2,872-dataset catalogue
      to the 395 Landgate publishes.
  - surface: SLIP OGC WFS
    params: [typeNames, bbox, srsName]
content_negotiation:
  style: query parameter, not Accept header
  detail: |
    ArcGIS REST selects the representation with `f` (html default, json/pjson/image/kmz);
    OGC services select with `format`/`outputFormat`; CKAN always returns JSON on /api/3/action
    and JSON-LD on /catalog.jsonld. Sending an Accept header does not change the ArcGIS
    default — `f=json` is required to get machine-readable output.
field_selection:
  supported: true
  note: ArcGIS `outFields` (comma list or `*`). CKAN has no sparse-fieldset parameter.
expansion:
  supported: partial
  note: CKAN `organization_show?include_datasets=true` and package_show inline `resources[]`
    are the only expansion-like behaviours. No generic expand parameter.
metadata:
  user_defined: false
  note: Catalogue metadata is publisher-controlled (CKAN package extras, ArcGIS documentInfo);
    consumers cannot attach their own metadata to anything.
request_tracing:
  request_id_header: none observed
  note: No X-Request-Id / correlation header was returned by any probed endpoint on 2026-07-26.
versioning:
  - surface: SLIP ArcGIS REST
    scheme: server-version-in-payload
    current: '12.1'
    detail: /public/rest/info reports currentVersion 12.1, fullVersion 12.1.0. The version is
      not in the URI, so a server upgrade changes behaviour under the same URLs.
  - surface: Data WA CKAN
    scheme: uri-path
    current: '3'
    detail: /api/3/action/*. /api/action/* also resolves to the same v3 surface.
  - surface: SLIP OGC
    scheme: query-parameter
    current: WMS 1.3.0, WFS 2.0.0
    detail: "`version` query parameter; WMS also answers 1.1.1."
error_envelope:
  rfc9457: false
  detail: errors/landgate-problem-types.yml
  surfaces:
  - surface: Data WA CKAN
    shape: '{"help": "...", "success": false, "error": {"__type": "...", "<field>": ["Missing value"]}}'
    http_status_used: true
    observed: [400, 409]
  - surface: SLIP ArcGIS REST
    shape: '{"error": {"code": <int>, "message": "...", "details": []}}'
    http_status_used: false
    caution: errors are returned with HTTP 200 — clients MUST inspect the body, not the status.
  - surface: SLIP OGC
    shape: XML ServiceExceptionReport / ows:ExceptionReport, or an ArcGIS Server HTML error page
    http_status_used: partial
rate_limits:
  published: false
  note: No rate-limit documentation, no RateLimit/X-RateLimit response headers observed on any
    probed endpoint (2026-07-26). The only published ceiling is the ArcGIS maxRecordCount of
    10000 features per query response.
caching:
  note: ArcGIS export/tile responses are cacheable; no explicit caching policy is published.
cross_links:
  errors: errors/landgate-problem-types.yml
  lifecycle: lifecycle/landgate-lifecycle.yml
  authentication: authentication/landgate-authentication.yml
  scopes: scopes/landgate-scopes.yml
  conformance: conformance/landgate-conformance.yml