PDTF schema lineage and semantic crosswalk
The PDTF schema contains the source paths used to define the Property Pack. A separate draft ontology was derived from that schema, its dictionary, glossary and supporting evidence. The SPDTF Property Pack candidate reconsiders the bounded profile by contextual meaning; it is neither a renamed schema nor a revised list of terms.
Bottom line
The main change is modelling authority and evidence discipline—not a move from JSON to RDF. A separate graph ontology was derived from the PDTF schema, but neither artefact has scheme authority. The Property Pack candidate asks domain-led questions afresh, keeps source facts separate from semantic proposals and assigns every candidate resource one explicit semantic home.
Crosswalk status
All 451 required Property Pack paths occur in the PDTF schema. Only 34 have an exact full-path entry in the schema-derived ontology provenance index. Consolidation and one-to-many modelling mean this is not a semantic coverage percentage. The maintained 451-row crosswalk from schema path to schema-derived construct or gap, and then to the Property Pack candidate, remains incomplete. It must record each retained, revised, consolidated, split or missing disposition.
This report distinguishes the PDTF schema, the separate schema-derived ontology, and the Property Pack ontology candidate. The candidate is an accelerated SPDTF component, not an adoption, release, replacement or external-authority claim.
Quantitative snapshot
Not a like-for-like size comparison
The schema-derived ontology covers evidence from the broader PDTF schema and overlays. The candidate covers only the required Property Pack profile and consolidates repeated source paths into semantic patterns. These figures describe each corpus; they do not rank quality or completeness.
Ontology derived from the PDTF schema
A separate technical corpus organised through concern modules and industry views; it is not an endorsed scheme.
- 321
- OWL resources
- 41
- classes
- 75
- object properties
- 205
- datatype properties
- 48
- value schemes · 319 concepts
- 402
- SHACL shapes · 66 indexed constraints
- 31
- overlay profiles
- 17
- diagnostic exemplars
SPDTF · Property Pack ontology candidate
A separate candidate namespace with explicit context ownership and source-item traceability.
- 159
- OWL resources
- 53
- classes
- 77
- object properties
- 29
- datatype properties
- 14
- value schemes · 85 concepts
- 45
- SHACL shapes · 100 property constraints
- 451
- required source data points
- 413
- source-topic concepts
Side-by-side comparison
Starting question
How can the PDTF schema, glossary, dictionary and form overlays be expressed and checked as linked data?
What semantic model is needed to represent the 451 required Property Pack data points correctly?
Evidence: PDTF schema reference · ADR-0066 · closed Property Pack scope
Business-data scope
Broad PDTF schema v3.5.0 package spanning the transaction schema and form overlays.
Closed initial scope of exactly 451 workbook rows marked Required.
Evidence: PDTF schema reference · Property Pack source coverage
Source authority
The PDTF schema, glossary, dictionary, ODR and council evidence all shaped the separate schema-derived graph.
The 451 rows fix coverage; domain evidence establishes meaning. The PDTF schema and schema-derived ontology are attributed evidence, not silent semantic seeds.
Evidence: Schema-derived ontology provenance · ADR-0066 · closed Property Pack scope
Architecture
One schema-derived ontology namespace organised into seven concern modules: foundation, property, agent, transaction, claim, governance and descriptive.
A separate candidate namespace with six bounded contexts, a deliberately small Common boundary and a DBT Smart Data scheme context.
Evidence: Schema-derived ontology reference · Property Pack contextual boundaries
Context ownership
Industry contexts are perspectives derived across the shared model and overlay profiles.
Every OPDA-defined resource and every source item has exactly one proposed semantic home.
Evidence: Schema-derived overlay profiles · ADR-0067 · context-owned candidate
From fields to meaning
The draft index is property-heavy: 41 classes, 75 object properties and 205 datatype properties.
The candidate consolidates repeated source paths into 53 classes, 77 object properties and 29 datatype properties.
Evidence: Schema-derived ontology reference · Property Pack ontology resources
Common meaning
A shared namespace is interpreted through concern modules and industry-context views.
Only meaning evidenced as genuinely shared belongs in the Common boundary; current cross-domain mappings remain unasserted.
Evidence: Property Pack contextual boundaries · ADR-0067 · context-owned candidate
Controlled vocabularies
The indexed corpus contains 48 SKOS schemes and 319 concepts across the broader schema-derived scope.
Fourteen value schemes contain 85 curated concepts; a separate source-topic layer contains 413 concepts.
Evidence: Schema-derived ontology reference · Property Pack controlled vocabularies
Validation
The indexed corpus contains 402 SHACL shapes, 31 form-overlay profiles and 17 diagnostic exemplars.
The candidate contains 45 target-class node shapes and 100 emitted property constraints, plus deterministic candidate checks.
Evidence: Schema-derived overlay profiles · Property Pack SHACL shapes · Property Pack validation evidence
Traceability
Term-level provenance and RML connect ontology resources back to their schema locations.
Stable Property Pack item IDs trace all 451 source points to candidate constructs, with direct and structural evidence distinguished.
Evidence: Schema-to-ontology RML mapping · Property Pack source coverage
Outputs and compatibility
OWL, SKOS, SHACL, RML, overlays, exemplars and dereferenceable documentation support the established JSON-schema ecosystem.
OWL, SKOS, SHACL, glossary, dictionary, coverage and validation artefacts form the current candidate package. JSON Schema and form projections are later outputs.
Evidence: Schema-to-ontology RML mapping · Property Pack standards profile
Authority and status
The PDTF schema is an existing technical implementation; the separate schema-derived ontology remains a draft reference for its committed corpus.
Public review candidate: 0.1.0-draft, machine-proposed and non-normative. Human review and recorded disposition remain required.
Evidence: Schema-derived ontology reference · Property Pack candidate overview · Property Pack validation evidence
Concrete semantic differences
Both models are graphs
The schema-derived ontology moved beyond the JSON tree and made explicit identity, class and relationship decisions. The Property Pack candidate changes how those decisions are sourced and owned; it does not introduce graph modelling for the first time.
The overlap is limited
Only 20 of 159 candidate resources share an exact local name with a schema-derived ontology resource. Only 16 also retain the same broad resource kind. Names alone do not establish equivalence.
Exact local-name matches with the same resource kind
This is a mechanical identifier check: each row uses the same local name in both models and is classified at the same broad level, such as a class or an object property. It identifies a useful starting point for crosswalk review; it does not establish that the definitions, identity rules, relationships or constraints mean the same thing.
16 names to review. Compare the meaning and evidence behind each pair before treating it as continuity.
Address class
applicationDate datatype property
builtForm object property
hasAddress object property
hasRegisteredTitle object property
heatingType object property
inclusionStatus object property
mediaUrl datatype property
ownershipType object property
postcode datatype property
priceQualifier object property
Property class
propertyType object property
RegisteredTitle class
Search class
titleNumber datatype property
Exact local-name matches that were reclassified
These names also occur in both models, but their broad resource kind has changed. For example, a term may be a class in one model and a property in the other. This is a clear signal not to infer a mapping from spelling alone: the modelling role has already changed and needs an explicit decision under the Category 8 mapping method.
4 reclassification questions. Each row needs a decision on whether the two uses are related, distinct or simply coincidental.
applicationType datatype property
councilTaxBand datatype property
designationType datatype property
leaseTerm object property
A substantive identity question remains open
The schema-derived ontology defines Property through spatial-material continuity and explicitly treats UPRN as a contingent identifier, not the identity criterion. The Property Pack ontology candidate Property candidate currently associates continuity with the same assigned UPRN. That is a semantic difference for working-group review—not a settled SPDTF decision.
Present in the schema-derived ontology, outside the initial Property Pack scope
Examples include Transaction, Person, Organisation, Buyer, Seller, Claim, Evidence and Trust Framework. Their absence from this candidate does not retire them; the 451-item Property Pack ontology candidate simply does not yet justify every broader schema-derived concept.
Prominent Property Pack ontology candidate patterns
Boundary Statement, Disclosure Statement, Fixture Schedule, Register Extract, Search Finding, Utility Service Record and Data Sharing Authorisation make Property Pack meaning more explicit within proposed semantic homes.
What carries forward from PDTF schema
- The PDTF schema remains useful implementation and migration evidence, while its derived ontology remains qualified semantic and provenance evidence.
- The linked-data standards family continues: RDF, RDFS, OWL, SKOS, SHACL, Dublin Core and provenance vocabularies.
- Existing definitions and design decisions can support a Property Pack decision when they are cited and reviewed.
- The build, validation and documentation lessons from the schema-derived ontology are reused without silently importing its semantic structure.
What this means in practice
Review meaning, not ontology syntax
Test definitions, identity criteria, context ownership, relationships and constraints against real domain evidence.
Keep using the current contracts
The Property Pack ontology candidate is not a replacement schema or migration target. Current integrations remain anchored to the published PDTF schema implementation.
Challenge the Common boundary
Review genuinely shared meaning and propose mappings without overriding each bounded context's internal vocabulary. Use the governed mapping workflow.
Make migration explicit
Record reviewed equivalence, transformation and projection decisions before generating replacement schemas or forms.
What the comparison does not prove
- A smaller or larger term count does not demonstrate better modelling: the business scopes and counting rules differ.
- Lexical matches do not establish identity, equivalence or a migration mapping between the two namespaces.
- Passing parser, SHACL and regeneration checks establishes technical integrity, not domain approval.
- Covering all 451 required Property Pack data points does not cover every schema-derived concept, PDTF schema field or overlay.
Evidence and method
The figures are calculated at build time from the current generated ontology model, the committed schema-derived ontology profile and exemplar directories, and the isolated Property Pack ontology candidate projections. The lexical comparison uses exact local names only and deliberately makes no equivalence claim. Narrative conclusions are constrained by the recorded scope and architecture decisions.
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