implemented 2026-08-18

Organise the site around SPDTF and the PDTF schema

Update 2026-09-05 — the Modelling section expands from eleven to twenty pages under its existing canonical route. “Understand ontologies” covers purpose, benefits, participation, reading and questions; “How we model SPDTF” covers the manifesto, eight ODR-0071 concerns, contexts, identity, modelling patterns, languages, mappings, validation and normative decision basis. Both paths use the shared page/navigation templates and searchable routes. ADR-0063 clarifies the selected source ODRs’ normative status without claiming candidate conformance. Existing routes and fragments remain; the frozen migration receipts remain historical evidence, not an inventory to rewrite for this content expansion. This amendment records local implementation, not a new publication authority.

Update 2026-09-03 — the canonical reader route for the Development destination is now /development/**, replacing /spdtf/**. This update supersedes every canonical /spdtf reader-route reference below while retaining those references as migration history. Internal navigation, search records, generated page routes and static tool paths use /development/**; the former /spdtf/** family is retired without redirects. Stable /pdtf/** RDF identifiers, /spdtf-2/** historical receipts and the SPDTF semantic-package workspace identifier do not change.

Update 2026-09-03 — the exact IA and family manifests remain the audit receipt for the completed migration, but are no longer evaluated on every unrelated release. Ongoing releases use the route/resource crawl and browser journeys; make check-ia-preservation remains available when a later migration needs to be compared with the frozen baseline. This changes gate proportionality, not the accepted route, authority, status or preservation decisions.

Update 2026-09-01 — display labels are shortened to Programme, Governance, Modelling, Development, Groups and Resources. The routes, destination keys, ownership and full terminology used within page content remain unchanged.

Update 2026-08-30 — ADR-0080 amends only the root homepage’s editorial composition. It replaces the separate status strip with integrated visible status facts while preserving the registry-derived six-card directory, exact destination order and URLs, sole-root rule and the PDTF schema’s nested third-party position. Publication and deployment remain unauthorised.

Update 2026-08-23 — public-homepage alignment implemented: / now derives six audience-led task cards from the accepted global-destination registry, in the same order. Its hero centres collaborative SPDTF work and visible authority status; the PDTF schema remains reachable only through SPDTF Development’s attributed third-party inputs rather than appearing in the hero, status strip, primary actions or peer destinations, or becoming the homepage’s organising story. Publication and deployment remain separate, unauthorised actions.

Update 2026-08-24 — duplicate-homepage retirement accepted: / is the sole OPDA Knowledge Base homepage and carries the full audience-led landing composition. The former /home route is retired without a redirect, rewrite alias or duplicate page; internal links must use /. This is a bounded route consolidation: every destination remains reachable from the root and the retirement receipt, route registry, crawl and preservation gates must record the absence of /home before release.

Update 2026-08-23 — accepted global-navigation and semantic-modelling correction: the six destinations are Programme, Governance, Semantic modelling, SPDTF Development, Working groups and Resources, in that order. SPDTF Development is the navigation label for /spdtf, not a renamed or adopted scheme. Semantic-modelling reader pages move as one exact-suffix family from /spdtf/ontologies and /spdtf/ontologies/** to /semantic-modelling and /semantic-modelling/**; the former routes are retired without redirects, rewrite aliases or duplicate pages. The PDTF schema remains a third-party SPDTF input beneath /spdtf/inputs/pdtf-schema/**, and stable /pdtf/** RDF identifiers remain unchanged. Implemented in repository source; release and deployment remain separately gated.

Update 2026-08-19: the user accepted this decision and authorised implementation in a separate feature worktree. The migration and release gates passed at audited evidence baseline 24f9fb4ca8405343dc13d2d4b7119a30e1b883d7, so this ADR is Implemented. This status does not mean published or deployed, and the redesigned root information architecture remains outside the frozen /v2/** route family.

Update 2026-08-19 — preview reconciliation: the initial implementation retained the legacy 13-section local rail even though the six destinations were present in the global header. src/lib/site-navigation.ts now composes every legacy section route under its current owner and drives all six left rails, breadcrumbs and exact-match previous/next sequences. The heading-derived page navigation is visible in-article or in the optional right rail, and container-responsive panels preserve the reading width. Status remains Implemented; this note makes no new deployment claim.

Update 2026-08-21 — accepted correction, partially implemented: ADR-0075 now treats /v2/** as the Property Pack ontology component of SPDTF, replaces the generic Development input branch with a canonical Property Pack workstream, exposes the PDTF schema and schema-derived ontology as distinct inputs, and records a Technical Working Group determination followed by later domain review. The Property Pack route consolidation and two-part PDTF schema navigation are implemented; ADR-0075 remains Accepted while its governance and complete lineage gates remain open.

Update 2026-08-19 — route-continuity exception: the operator subsequently chose one canonical /spdtf/property-pack/** family and explicitly declined compatibility routes for /v2/** and /modelling/property-pack. ADR-0075 supersedes this ADR’s stable-route clauses only for those Property Pack routes. Atomic information, fragment and feedback-thread preservation remain release gates.

Update 2026-08-20 — local navigation categories: each left-rail category heading is now its canonical landing-page link, with a separate disclosure button for child pages. The landing no longer appears as a duplicate child, but remains in breadcrumb and previous/next sequences. The schema-derived ontology branch further groups lineage, audience views, architecture, terms, validation, trust and tooling beneath substantive linked landings; nested model tiers retain their real overview pages. Existing routes remain available and keep their authority and status.

Update 2026-08-20 — semantic-modelling depth: the implemented branch now has two linked audience paths: Understand ontologies, including a model-reading guide; and How we model SPDTF, including the evidence-up method and explicit modelling rules. The repeated in-page journey widget is removed in favour of the shared left navigation, page contents and previous/next sequence. Standards pages distinguish specification maturity, OPDA governance status and actual candidate use. This implements the semantic-documentation portion of ADR-0075 without promoting that still-Accepted decision or the Proposed ADR-0065/0068 workflows.

Update 2026-08-21 — PDTF schema route consolidation: ADR-0076 supersedes this ADR’s stable-route clauses for PDTF schema reader documentation. Those pages move beneath /spdtf/inputs/pdtf-schema/**; their old routes and the /manual/** aliases are removed without redirects. Atomic information, fragment, status and feedback-thread preservation remain release gates. /pdtf/** is not a compatibility family: it remains the unchanged RDF identifier and dereferenceability namespace.

Update 2026-08-21 — decision-corpus navigation: Governance now links once to the ADR index and once to the ODR index. Individual decision records remain canonical pages reached from those indexes, but no longer expand the left rail or participate in its previous/next sequence.

Update 2026-08-21 — Governance and working-group guidance: the Governance rail now mirrors the six substantive clusters on its landing page through linked gateways, while retaining every existing child route and its own status. Working groups now exposes a separate member guide for access, Teams, SharePoint evidence, meetings and model review before the eight workspaces. Recruitment remains a standalone public route, and the guide does not expose private operational links or promote proposed ADR-0065/0068 rules. This note makes no publication claim.

Context and Problem Statement

The website currently presents thirteen peer navigation sections. Seven of them — Modelling, Model, Ontology, Mapping, Schema, Implementation and Adoption — document the PDTF schema, supporting material and schema-derived semantic corpus. Those descendants do not have uniform authority: technical publication does not make the schema an OPDA-endorsed scheme, and the schema-derived ontology, model, mapping and stub pages retain their own maturity and review status.

The current programme is SPDTF, the Smart Property Data Trust Framework: the first scheme draft being written collaboratively across industry and stakeholders. It uses domain-led, evidence-up modelling through bounded-context working groups, with a separate Interoperability Working Group and human authority over meaning. The PDTF schema, its schema-derived ontology and participant resources are inputs; they contribute compatibility, constraints, coverage and migration evidence but do not determine SPDTF domain meaning. This is a schema-to-scheme continuation, not a numbered-version succession.

The current navigation mixes programme context, PDTF schema implementation, the machine-generated Property Pack seed, current governance and resources. It therefore cannot reliably tell readers which material is published, under development, non-normative or historically named.

It also provides no canonical current journey explaining why ontologies are used, how the working groups turn evidence into context-owned candidates, which semantic outputs stay aligned, how the eight formal modelling concerns differ from the presentation’s eleven themes, or which standards are targets, candidates, projections or legacy tools.

DBT Smart Data is an external, cross-economy government programme enabled by the Data (Use and Access) Act 2025. Property is under evidence gathering and prospective scheme design; no operating statutory property scheme or government-approved SPDTF standard has been identified. OPDA work is recognised as market activity and evidence, not as delegated government authority.

ADR-0064 requires a follow-on decision for the coherent information architecture, status model, migration plan and release gate. This implementation satisfies that follow-on requirement; ADR-0064’s unrelated decisions remain operative.

Decision Drivers

Make SPDTF participant review the primary development surface.
Keep the PDTF schema and schema-derived ontology directly findable and distinct.
Prevent machine-generated material from acquiring human standards authority.
Use SPDTF for current collaborative scheme work and PDTF schema for the existing technical input.
Define one cross-programme authority and status system.
Explain the ontology method in business language without conflating semantic meaning, validation, downstream projections or approval.
Make standards status, conformance scope and mapping type explicit.
Account for every reader route and preserve stable semantic identifiers before changing navigation paths; a reader-route preservation receipt does not require a compatibility route.
Apply migration rules to complete generated route families, not individual pages.

Considered Options

Mirror the PDTF schema and SPDTF. Rejected because this would imply two equivalent generations or schemes rather than an asymmetric schema-to-scheme continuation.
Keep the thirteen-section navigation. Add work-area and status banners to the current structure.
Use an asymmetric task-and-authority architecture (chosen). Separate the two bodies of work while sharing Programme, Governance and Resources, and expose direct Semantic modelling and Working groups task paths.

Decision Outcome

Accepted: adopt six global destinations, in this order:

Programme.
Governance.
Semantic modelling.
SPDTF Development.
Working groups — a shortcut to the single canonical family within SPDTF Development.
Resources.

SPDTF Development is the navigation label for /spdtf; it does not rename SPDTF, create a numbered generation or imply adoption. SPDTF is the current collaborative scheme draft in development, not an adopted standard. The PDTF schema input area beneath SPDTF Development contains the existing schema, supporting material and separately identified schema-derived ontology, each with its own status. It must not be presented as an OPDA-endorsed predecessor scheme.

The existing /v2/** corpus is labelled SPDTF Property Pack candidate — machine-generated pre-draft — non-normative — no working-group review or approval recorded. It remains structured and reviewable, but is not called the complete SPDTF ontology, an approved working-group draft or a replacement contract.

Governance owns one versioned registry with separate fields for work area, authority, maturity, version and provenance. Interoperability is a peer of domain working groups within SPDTF development and links to Governance for its decision rights.

Semantic modelling is one canonical peer global destination at /semantic-modelling, with two audience paths. Understand ontologies explains why ontologies are used and how to read the model. How we model SPDTF documents the evidence-up method, six-part semantic package, context boundary, modelling rules, coverage, standards, evidence and mappings, validation and projections.

The branch distinguishes three taxonomies:

six reviewable semantic outputs — glossary, dictionary, taxonomies, controlled vocabularies, resources and relationships;
eleven participant-facing workshop themes arranged under Meaning, Trust, Correctness and Exchange; and
eight formal ontology-coverage concerns from ADR-0063/0067, each disposed as model here, reuse shared, boundary contribution or not applicable.

Its standards profile records purpose, exact version/conformance, mechanism, status, owner, evidence/decision and re-open trigger. RDF 1.2 Basic, a portable SPARQL 1.2 subset and SHACL 1.2 Core are bounded targets; broader claims require feature evidence. External vocabularies and modelling frameworks are assessed rather than inherited. JSON Schema, JSON-LD, forms, APIs and documentation are tested projections, not independent semantic authorities.

“Mapping” is always qualified: legacy RML schema–ontology verification, planned JSON-LD contexts, current cross-context semantic mapping, Property Pack coverage links, or an optional runtime transformation. Coverage links are not RML/R2RML.

Semantic-package workspace contract identifier

The canonical public identifier for the semantic-package workspace contract is https://opda.org.uk/spdtf/semantic-package/workspace-contract, at revision 2026-08-22. It supersedes the intermediate https://opda.org.uk/spdtf-2/semantic-package/workspace-contract identifier at its 1.0.0 state solely because the Chair-authorised terminology correction changes the public identifier. The intermediate identifier is retained only as migration metadata: it is not a current alias or compatibility route, and neither its path nor its version denotes an SPDTF generation. The contract’s semantic-package meaning and evidence history are preserved; this remint is the bounded exception required to remove the withdrawn public version label. Stable /pdtf/** identifiers for the separate schema-derived ontology remain unchanged.

Programme owns the canonical DBT Smart Data context. Governance describes external statutory and prospective-scheme constraints, Resources holds official sources, and SPDTF development links relevant evidence as an input. In accordance with ADR-0063, the working-group roster includes an OPDA-internal DBT Smart Data cross-sector scheme-design group. It is not a government-established property-scheme body and cannot confer statutory or government-approved status on SPDTF.

The complete hierarchy, route placement, page contract and migration gates are defined in docs/spdtf-information-architecture.md.

This ADR amends only the top-level navigation and content-owner placement clauses of ADR-0002, ADR-0041, ADR-0059 and ADR-0062. Their stable routes, ontology-generation rules, mapping provenance, Smart Data source treatment and other technical decisions remain. It does not supersede those ADRs as a whole.

Consequences

Good, because SPDTF development, the PDTF schema and the schema-derived ontology become unambiguous.
Good, because participants can enter through working groups and review meaning in business language.
Good, because implementers retain a two-interaction path to schemas and validation.
Good, because one status system prevents competing work-area-specific authority claims.
Good, because participants gain a plain-language ontology journey while implementers retain qualified technical views.
Good, because six outputs, eleven themes and eight formal concerns cannot silently collapse into one misleading taxonomy.
Good, because the current route inventory becomes a deterministic migration ledger.
Bad, because six new labels will disrupt familiarity with the thirteen-item header.
Bad, because coherent status metadata must be applied across thousands of pages.
Neutral, because route continuity is decision-specific: semantic-modelling content and feedback identity are preserved while the former reader routes intentionally disappear.

Confirmation

The original information architecture was Implemented on the isolated feat/spdtf-2-ia branch. Its audited implementation baseline is 24f9fb4ca8405343dc13d2d4b7119a30e1b883d7; the status-change commit is a later governance-only change. The 2026-08-23 global-navigation correction is implemented in repository source; release and deployment remain separately gated. Neither the historical commits nor this correction authorises publication or deployment.

Human approval was required before acceptance; implementation then required the complete migration and release gates listed below.

The original branch contains the route/status registry, canonical landings and workspaces, search facets, runtime journeys, and exact preservation manifests. It satisfied the then-current gates for:

a disposition for every route, generated family, bundled artefact, published source object and compatibility alias in the current-site IA inventory;
checksum/consumer preservation ledgers for sources, council records, ontology/data artefacts, support assets and runtime authentication, comments and submissions;
one canonical working-group URL family under SPDTF;
one canonical two-audience Ontologies and semantic modelling journey with the exact six/eleven/eight distinction and four category dispositions;
a status-controlled standards profile and unambiguous mapping vocabulary;
the revisioned semantic-package workspace contract at its canonical SPDTF identifier, competency questions, coverage receipts and immutable candidate diffs so projections cannot become independent meaning sources;
inherited five-field status metadata on every generated page;
a machine-readable migration manifest;
task tests for participant, implementer and governance journeys;
complete route, fragment, search, accessibility, responsive, keyboard, visual, unit and build gates;
a coherent release rather than piecemeal changes.

The 2026-08-23 correction additionally requires:

the exact global order Programme, Governance, Semantic modelling, SPDTF Development, Working groups and Resources;
the public root derives six audience/task cards with those exact labels and URLs from the global registry, introduces SPDTF’s collaborative purpose and in-development authority, and gives the PDTF schema no hero, status, primary-action or peer position;
one canonical top-level /semantic-modelling/** reader family containing both audience paths, with no Semantic modelling branch beneath SPDTF Development;
exact-suffix preservation receipts from /spdtf/ontologies and /spdtf/ontologies/**, while emitting no old route, redirect, rewrite alias or duplicate page; and
unchanged placement and authority for /spdtf/inputs/pdtf-schema/**, with every stable /pdtf/** RDF identifier and representation unchanged.

The 2026-08-24 homepage-route consolidation additionally requires:

/ to be the sole OPDA Knowledge Base homepage, with the full root landing composition and all six canonical destination cards; and
/home to be classified as retired and absent from the emitted site, internal links, rewrites and redirects, with a route-retirement receipt that records its former role and confirms that every destination remains reachable from /.

The schema-v5 preservation receipt accounts for 562,664 baseline information-block occurrences: 561,743 exact, 868 source/hash-bound semantic reframes and 53 provenance-bound superseded navigation copies. Its eight exact families are the source archive, council Markdown, ontology artefacts, deployed data, UI assets, image assets, ontology tools and the 690-route /v2/** atomic seed. The checker rejects a new route beneath /v2/**.

At the evidence baseline, make ci-browser passed the 2,604-page Astro data build, 3,485/3,485 HTML preservation check, 3,485-HTML/5,284-file crawl with zero unresolved or unlinked outputs, and 84/84 Playwright tests. The different counts are deliberate: Astro reports pages it renders, the preservation/crawl includes copied static HTML, and the emitted-file count also includes non-HTML assets. make ci passed 140/140 unit tests, 5/5 schema tests, zero schema drift, 74 ADR records, and every ontology, documentation, graph and IA-parity gate. Two consecutive production data builds kept content-addressed asset tokens and strict preservation stable.

Fable and Claude Sonnet each scored the implementation 98/100 with zero blockers; the OpenAI Devil’s Advocate scored it 100/100 with zero blockers. A native subscription Claude–Codex deliberation then returned accepted with publication authority withheld. These reviews corroborate the executable gates; they do not replace them.

ADR-0064’s follow-on IA requirement is complete. Its unrelated decisions remain operative.

Rules

Use SPDTF for the first collaboratively authored scheme draft and its development work.
Use PDTF schema for the existing JSON Schema, dictionary, glossary and overlays; use schema-derived ontology for the technical ontology extracted from that corpus.
Do not imply that the PDTF schema or schema-derived ontology was an OPDA-endorsed predecessor scheme.
Do not call SPDTF an adopted standard before recorded governance approval.
Do not present SPDTF as an approved statutory property Smart Data scheme or treat OPDA participation in government forums as delegated authority.
Do not classify the Property Pack seed as working-group reviewed.
Do not present technical validation as semantic approval.
Do not infer child-artifact authority from the PDTF schema parent label.
Do not inherit legacy standards or modelling-framework choices into SPDTF without an explicit profile disposition.
Do not conflate the six semantic outputs, eleven workshop themes or eight formal ontology-coverage concerns.
Do not use an unqualified “mapping” label.
Do not create duplicate governance, status, glossary or working-group records.
Do not redirect a route without a recorded semantic-equivalence decision and test.
Use / as the sole public Knowledge Base homepage. Do not emit, redirect, rewrite, alias or duplicate /home; record its retirement in the migration evidence.
Use /semantic-modelling and /semantic-modelling/** for semantic-modelling reader pages. Do not emit, redirect, rewrite, alias or duplicate /spdtf/ontologies or /spdtf/ontologies/**; migration receipts and retained feedback identity are not compatibility routes.

Vote and Dissent

A non-voting chair convened a hierarchical, specialised council using Raft consensus. Independent native-model priors came from OpenAI gpt-5.6-terra at high effort, OpenAI gpt-5.6-sol at xhigh effort, and Anthropic claude-fable-5 at maximum effort. Bounded cross-examination used Fable at high and medium effort.

The final OpenAI ballot accepted the original core proposal three to zero. Its earlier 98/100 results and a scoped 100/100 ontology review remain historical evidence only. For the integrated implementation, Anthropic Fable and Claude Sonnet scored 98/100, the OpenAI Devil’s Advocate scored 100/100, and the native Claude–Codex deliberation accepted the transition; every review reported zero hard failures.

Held historical dissent: Fable would have ordered the PDTF schema before SPDTF because implementation was the majority task. The 2026-08-23 operator decision resolves the global order and keeps the PDTF schema as a nested third-party input.

More Information

Amendments

2026-08-24 — case-independent Lease Term representation routes. The two source-model identifiers remain exact, but their static representation documents move to lowercase type-scoped paths. The migration registry, generated links, crawl and preservation receipt enforce the move and absence of old-route compatibility.
2026-08-24 — one canonical homepage. The root route is the sole OPDA Knowledge Base homepage. /home is retired as a duplicate route without backwards compatibility, while all six global destinations remain available from /.
2026-08-23 — Semantic modelling becomes a peer global destination. The global order is Programme, Governance, Semantic modelling, SPDTF Development, Working groups and Resources. Semantic-modelling reader pages move to /semantic-modelling/** as a clean route break with no old-route compatibility. The PDTF schema remains a nested third-party SPDTF input, and stable /pdtf/** identifiers remain unchanged.
2026-08-23 — PDTF schema is an SPDTF third-party input. ADR-0077 removes the PDTF schema from the global destination set and hosts it beneath /spdtf/inputs. Route containment does not confer SPDTF authority, adoption or authorship.
2026-08-22 — Chair-authority terminology correction. Maria Harris, OPDA Chair, clarified that the inherited version-numbered draft technical scheme was not created collaboratively and was not endorsed by OPDA. The site architecture therefore presents the existing PDTF schema and its separately identified schema-derived ontology as evidence and implementation inputs, and SPDTF as the first collaboratively authored scheme draft. The governing relationship is schema to scheme, not one numbered standard generation replacing another. Reader routes move to /spdtf/inputs/pdtf-schema/** and /spdtf/**; stable /pdtf/** RDF identifiers and factual historical provenance remain unchanged.
2026-08-22 — semantic-package contract remint. The canonical workspace-contract identifier is now https://opda.org.uk/spdtf/semantic-package/workspace-contract, revision 2026-08-22. It supersedes the intermediate /spdtf-2/ identifier at its 1.0.0 state only because the public identifier embedded the withdrawn terminology; the old identifier survives as migration metadata and carries no SPDTF-generation meaning.