ONS Open Knowledge Format

okf-ons is a metadata-only discovery layer for public statistics exposed through Office for National Statistics services. It is designed to help a person or an agent find the exact dataset, see easily confused alternatives, understand the statistical-quality evidence that is available, and prepare a non-executing candidate plan that a downstream service must live-validate and authorise before retrieval.

The project deliberately separates four jobs:

1. The static OKF bundle discovers and explains datasets, versions, dimensions, provenance, standards evidence, and alternatives.

2. OKF Explorer narrows and compares a large static corpus without an LLM or a hosted search service.

3. The repository's local MCP broker gives AI clients bounded access to the same frozen metadata and prepares a non-executing selection plan.

4. A downstream live-data MCP server executes an ONS or Nomis query only after the required dataset-specific choices are complete.

The local broker is not the downstream live-data server: it makes no network calls and returns no observation values. No observations, API keys, or private data are stored in the bundle.

OKF 0.2 core and Explorer extensions

The checked-in bundle targets Open Knowledge Format 0.2. Its generated portable core starts at index.md, which declares okf_version: "0.2" and progressively links to typed concepts for the catalogue, frozen snapshot, four source lanes, provider state, governance, standards and MCP selection.

Every concept uses generated and sources. No verified event is claimed: the automated checks prove structural conformance and frozen-input integrity, not human review or statistical truth. No stale_after value is invented while the governed freshness policy remains undefined. Lifecycle status is therefore explicit and live execution continues to require provider revalidation.

The large-corpus descriptor, JSON/YAML-LD, static search, facets, relationships, federation, integrity catalogues and provider datapacks remain additive Explorer extensions. New concepts also retain the v0.1 timestamp and # Citations fallbacks so older consumers can continue best-effort discovery while v0.2 consumers prefer generated and sources.

Related MCP server: ONS + Nomis MCP server

Access and documentation

These are the canonical entry points for the Pages deployment from main. The immutable application release v0.2.0 predates the OKF specification 0.2 migration and remains available as historical release evidence.

Live and machine-readable access

Subordinate dataset, resource, search and selection-option shards are discovered through the data and search manifests above; their generated paths are not independent stable entry points.

Repositories, release and provenance

• OKF-ONS repository, all GitHub Releases, and release v0.2.0

• Immutable v0.2.0 downloads: bundle ZIP and SHA-256 digest

• OKF Explorer repository

• Pinned ONSdigital Explore Local Statistics commit

• Source register, OKF publication metadata, release snapshot manifest, current enrichment snapshot manifest, and release changelog

Documentation map

• Product and demonstration: demo guide, product contract, ONS hackathon brief, and accessibility statement

• Repository operation: repository guide, security policy, release changelog, and CI publication workflow; the AI-client change fragment is retained as pre-release history

• Metadata and assurance: metadata model, scope and denominator, and standards register, plus the timed metadata-enrichment campaign and the OKF Explorer campaign handoff, with the machine-readable stopping audit

• MCP and AI access: MCP selection contract, MCP client rollout, and agent-access and evaluation proposal

• Evaluation: evaluation method, cross-client trial analysis, and the machine-readable study, client registry, tasks, expected results, personas and journeys, issue register, and gold queries

• Research and communications: research register, research evidence manifest, architecture manifest, governed-AI research prompt, governed-AI architecture report, and publication draft

• Dated AI-client research records: Claude Desktop access trace, Antigravity briefing, and Antigravity postmortem

• Portable research outputs: Claude trace DOCX, M365 access briefing DOCX, M365 hosting research DOCX, governed-AI presentation, enterprise-AI presentation, and the discovery-bridge visual

OKF Explorer can load the bundle today through the direct link above. A separate Explorer registry and presentation update is recommended so the bundle is suggested without pasting its URL and the new authority, rights and governance fields are shown as first-class UI rather than only in raw JSON.

SDMX support

The bundle registers SDMX 3.1 (ISO 17369), maps seven canonical OKF fields to SDMX concepts, and preserves the Nomis lane's SDMX agency, identifier, version, dimension order, component roles and code-list references. Nomis selections also retain bounded FREQ code-label options and strict available TIME extents where that evidence is usable. FREQ is statistical/reference frequency, not publication cadence, and TIME-period revision annotations are not dataset revision status. All other required dimensions still need live validation and selection; completed live execution uses MCP-Geo's nomis_query.

The bundle is not itself an SDMX message. It is serialized as JSON-LD using DCAT 3, SKOS, PROV-O and RDF Data Cube terms, with no SDMX namespace in its context. The generated data/standards/sdmx.json reports the exact mapping and Nomis evidence counts without asserting upstream conformance or certification.

Monday demonstrator

The pre-hackathon demonstrator is frozen so the Monday presentation can use a reproducible, reviewable snapshot rather than changing live acquisitions. It publishes:

• a source and coverage ledger that makes incompleteness explicit;

• a frozen 5,097-record metadata snapshot from ONS Data API (337), Nomis (1,617), ONS Open Geography (3,035), and ONS Explore Local Statistics (108);

• qualified source-producer, service-operator, bundle-publisher and semantic authority roles, with explicit non-endorsement;

• deterministic search and first-class filter postings;

• evidence-backed alternative/contrast relationships;

• exact Census table-code reconciliation across ONS Data API and Nomis;

• statistical-quality and standards evidence without false assurance claims;

• an MCP selection-plan contract; and

• a reproducible retrieval and metadata-quality evaluation report.

The immutable snapshot ID monday-2026-07-17-r2 extends the Friday 17 July freeze with the pinned ELS metadata projection. The r2 suffix prevents the expanded corpus from reusing the original v0.1 snapshot identity; “monday” is the demonstrator name, not a claim that 17 July was a Monday.

The Explore Local Statistics lane is a deterministic, allowlisted projection of the pinned application submodule. It carries 108 ONS-curated indicators from 24 attributed producers, explains 12 unpublished manifest entries, preserves 46 valid historical aliases, and removes observation values, status arrays, value domains, binaries and geometry. It is a development fixture rather than a claim that the internal ELS API is a stable public execution contract. Its verified Git commitAsOf is kept separate from acquisition time; the frozen fixture does not invent a retrieval timestamp that was not recorded.

The bundle also publishes a provider datapack that makes the ELS snapshot/live distinction visible without weakening reproducibility. The governed snapshot remains pinned to 795eaf2 from 17 July 2026. A separately reviewed upstream reference at d5f0ac9 records a known example difference: average house price ends in April 2026 in the snapshot and May 2026 in the reviewed reference. That reference was last checked on 23 July 2026, is explicitly external and is not a live validation. Its comparison is a non-exhaustive reviewed example, not a claim that all 108 indicators were compared. The descriptor hashes the provider manifest and the manifest hashes the pack, so the dated review cannot be replaced under the same snapshot ID without failing Explorer's integrity checks. See the provider datapack contract.

This experimental bundle is independently published by the OKF ONS project. Source attribution does not imply endorsement by ONS or another producer.

Build

Python 3.11 or later is required. A recursive clone is required because normal GitHub source archives do not contain the pinned ELS submodule. The release bundle ZIP linked above is the self-contained publication artifact.

To reproduce v0.2.0 from its checked-in frozen snapshot:

git clone --recurse-submodules --branch v0.2.0 \
  https://github.com/chris-page-gov/okf-ons.git
cd okf-ons
python scripts/project_els_snapshot.py \
  --submodule-dir vendor/explore-local-statistics-app \
  --output output/ons-explore-local-statistics.json
cmp output/ons-explore-local-statistics.json \
  source/demo-snapshot/ons-explore-local-statistics.json
python scripts/build_bundle.py \
  --snapshot-dir source/demo-snapshot \
  --output bundle
python scripts/build_bundle.py \
  --snapshot-dir source/demo-snapshot \
  --output bundle \
  --check
python scripts/check_okf_v02.py bundle

The metadata-enrichment campaign also includes immutable successor snapshot metadata-enrichment-2026-07-21-r6. Relative to the v0.2.0 snapshot, r3 refreshes the bounded ONS Data API catalogue, r4 adds bounded metadata-only Nomis compact overviews, and r5 adds only the reviewed dimension projection from each frozen ONS latest-version URL. r6 follows the exact FREQ and TIME codelist references in the frozen r5 Nomis cohort and retains only code-label metadata and explicit period revision-status annotations. The ONS Data API, Explore Local Statistics and Open Geography source envelopes in r6 are byte-identical to r5. Rebuild and profile r6 without network access:

python scripts/build_bundle.py \
  --snapshot-dir source/metadata-enrichment-2026-07-21-r6 \
  --output bundle
python scripts/build_bundle.py \
  --snapshot-dir source/metadata-enrichment-2026-07-21-r6 \
  --output bundle \
  --check
python scripts/profile_metadata_gaps.py \
  --bundle bundle \
  --output evaluation/metadata-completeness/current.json

The live Pages and Explorer URLs above still serve governed release v0.2.0. The r6 campaign snapshot is checked in as governed campaign evidence but remains an undeployed release candidate until the release metadata and Pages-selected snapshot are deliberately switched.

The measured batch history, metric definitions, timings and machine-readable profiles are linked from the metadata-enrichment campaign, including the stopping audit.

For an existing clone, run git submodule update --init --recursive before the projector. To acquire a future snapshot, keep the raw cache outside the repository, use --mode refresh, and choose a new immutable identity—never overwrite an existing snapshot. To refresh only the ONS catalogue while carrying the other validated source envelopes forward:

python scripts/acquire_snapshot.py \
  --cache-dir /path/to/raw-cache \
  --output-dir source \
  --snapshot-id NEW_UNIQUE_SNAPSHOT_ID \
  --base-snapshot source/metadata-enrichment-2026-07-21-r4 \
  --source ons-data-api \
  --mode refresh \
  --page-size 1000 \
  --maximum-pages 1 \
  --require-complete

To reproduce or refresh the bounded Nomis compact overviews, use the validated pre-enrichment r3 snapshot as the base: replacement envelopes are digest-bound to that exact cohort and enrichment snapshots are not chained as acquisition bases. First acquire into an external replacement envelope, then compose that envelope over r3. The acquisition script independently derives its cohort from the frozen Nomis source and publishes neither raw responses nor cache paths:

python scripts/acquire_nomis_overviews.py \
  --snapshot-dir source/metadata-enrichment-2026-07-21-r3 \
  --cache-dir /path/to/raw-cache \
  --output /path/to/nomis-overviews.json \
  --limit 1617 \
  --mode refresh \
  --request-interval 0.2
python scripts/acquire_snapshot.py \
  --cache-dir /path/to/raw-cache \
  --output-dir source \
  --snapshot-id NEW_UNIQUE_SNAPSHOT_ID \
  --base-snapshot source/metadata-enrichment-2026-07-21-r3 \
  --replacement-acquisition /path/to/nomis-overviews.json \
  --require-complete

To reproduce or refresh the bounded ONS latest-version dimension projection, use r4 as the validated pre-enrichment base. The acquisition follows only the 337 exact links.latest_version.href values frozen in r4, stores only the allowlisted projection in an external cache, and does not fetch observations, dimension options, codelists or downloads:

python scripts/acquire_ons_version_metadata.py \
  --snapshot-dir source/metadata-enrichment-2026-07-21-r4 \
  --cache-dir /path/to/external-cache \
  --output /path/to/ons-version-metadata.json \
  --limit 337 \
  --mode refresh \
  --request-interval 0.5
python scripts/acquire_snapshot.py \
  --cache-dir /path/to/external-cache \
  --output-dir source \
  --snapshot-id NEW_UNIQUE_SNAPSHOT_ID \
  --base-snapshot source/metadata-enrichment-2026-07-21-r4 \
  --replacement-acquisition /path/to/ons-version-metadata.json \
  --require-complete

To reproduce or refresh the bounded Nomis FREQ/TIME codelist projection, use r5 as the exact base. The acquisition follows 3,234 frozen metadata-only codelist references sequentially, retains explicit failed outcomes in the denominator, and stores only its allowlisted projection in a versioned external cache:

python scripts/acquire_nomis_codelists.py \
  --snapshot-dir source/metadata-enrichment-2026-07-21-r5 \
  --cache-dir /path/to/external-cache \
  --output /path/to/nomis-codelists.json \
  --limit 1617 \
  --mode refresh \
  --request-interval 0.2
python scripts/acquire_snapshot.py \
  --cache-dir /path/to/external-cache \
  --output-dir source \
  --snapshot-id NEW_UNIQUE_SNAPSHOT_ID \
  --base-snapshot source/metadata-enrichment-2026-07-21-r5 \
  --replacement-acquisition /path/to/nomis-codelists.json \
  --require-complete

For a full registered-source refresh, first produce the pinned local ELS projection, then acquire all HTTP lanes and include it:

python scripts/project_els_snapshot.py \
  --submodule-dir vendor/explore-local-statistics-app \
  --output /path/to/els-projection.json
python scripts/acquire_snapshot.py \
  --cache-dir /path/to/raw-cache \
  --output-dir /path/to/public-snapshots \
  --snapshot-id NEW_UNIQUE_SNAPSHOT_ID \
  --mode refresh \
  --projected-acquisition /path/to/els-projection.json \
  --require-complete

Acquisition is resumable and external. bundle/ is deterministic from a validated frozen snapshot.

The sendable ONS hackathon brief explains the work package, demo route and questions for ONS. See also the standards register, evaluation method, and scope and denominator.

AI access research and evaluation

The repository preserves and SHA-256-pins 18 July 2026 trials from Claude Desktop Cowork, Google Antigravity CLI and Microsoft 365 Copilot Researcher in research/. Only technically reviewed, sanitized public DOCX derivatives are published. The original Office packages are withheld outside Git and identified only by their pinned source hashes. Normalized observations keep public derivatives, session-reported identity, later verification and our interpretations distinct.

The case study now seeds a provider-neutral, fixture-safe harness:

python3 scripts/ai_client_harness.py validate
python3 scripts/ai_client_harness.py validate-research
python3 scripts/ai_client_harness.py clients --initial-only
python3 scripts/ai_client_harness.py probe-clients
python3 scripts/ai_client_harness.py tasks

The harness defines OKF, open-web and raw-API arms; eight development smoke tasks; six ONS-specific personas and eight journeys; a ten-item observed-issue register; a common structured answer; answer-bound independent assessment; deterministic component scoring; enforced-versus-self-reported separation; and separate readiness outcomes so a blocked client is not scored as a wrong answer. CI performs no live, authenticated or paid model calls.

A dependency-free, metadata-only MCP broker now exposes deterministic descriptor, search, exact-record, comparison, read-only MCP-plan and answer-submission tools. Antigravity CLI (agy) can load it from the repository-scoped .agents/mcp_config.json. That configuration was added after the preserved Antigravity trial; no new paid or live model run is claimed. The broker uses the frozen corpus, makes no network call, stores no credentials and returns no observation values.

AI-system connection map

The MCP rollout guide is the canonical setup and status guide for every AI surface in the evaluation registry. It distinguishes four access and deployment layers:

• Static bundle access: any permitted HTTP client can read the Pages descriptor and JSON, but native fetch limits differ by host.

• Local metadata MCP: command-line and desktop clients that support local stdio MCP can start scripts/okf_ons_mcp.py. The committed AGY workspace configuration is the only repository-scoped client configuration; the guide gives the separate Codex, Claude, Gemini, VS Code/Copilot and Inspector routes without treating installation as a successful trial.

• Planned remote metadata MCP: ChatGPT custom apps need a supported remote endpoint or tunnel route; Claude Research, remote-session Cowork and Microsoft 365 Copilot Researcher need an authenticated remote endpoint. Desktop-local Cowork may use local MCP, subject to device policy. This repository deploys neither a remote endpoint nor a tunnel. The M365 federated-connector route is documented, but it has not been created or enabled for a tenant.

• Downstream live MCP: once selection is complete, a separate ONS or Nomis integration may execute the plan. The repository broker deliberately never does so.

The machine-readable client-profiles.json is the complete 16-profile client registry; study.json pins the evaluation design. The public tasks.json, personas-and-journeys.json and issue-register.json keep the tasks, users, journeys, observed failures and remediations in lockstep with that design.

See the cross-client trial analysis for the evidence, issue/remediation matrix, personas, efficiency protocol and prioritized work packages.

What “all” means

The repository may describe itself as covering all public ONS metadata only when every in-scope source in source/source-register.json has a measured denominator and the generated coverage ledger reports unexplained_omissions = 0.

Observation cells, secure microdata, and duplicate binary payloads are intentionally out of scope. See scope and denominator.

Licensing

Code is MIT licensed. Source metadata remains subject to its stated upstream licence, often the Open Government Licence v3.0. The bundle makes no blanket licence claim: ELS record rights remain not-evaluated pending source-by-source review, and generated records preserve the available source and rights evidence.