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Diagnostic Exemplar

opda:DiagnosticExemplar

Diagnostic Exemplar

A Diagnostic Exemplar is a minimal worked-example dataset that exposes exactly one Identity-Criterion-bearing surface, used as input to a Council session’s validation of that Identity Criterion.

Why it matters

Exemplars are how the Linked Data Council pressure-tests an Identity Criterion before it ratifies it. A modelling proposal that survives a registered freehold house but breaks on an unregistered house pre-first-registration is not ratified until the breakage is reconciled. Diagnostic Exemplars are the receipts for that pressure-testing — they exist so a reviewer can replay the original test and confirm the IC still discharges its hard cases.

If you are a Council member, an ontology integrator, or an auditor checking why a particular IC was chosen, you want the Exemplar that ratified it.

Hard cases

  • Registered freehold house. The textbook case — title-number lineage holds, UPRN is stable, address is canonical. The Exemplar exists so the IC’s behaviour on the boring case is not assumed.
  • Unregistered house pre-first-registration. No HMLR title number. The Exemplar forces the IC to handle the absence of registry evidence without collapsing identity.
  • Flat with split UPRN. One physical flat receives a UPRN split into two address-records. The Exemplar forces the IC to choose between collapsing identity (one Property) and splitting it (two Properties).

Identity Criterion

Each Diagnostic Exemplar is identified by the named hard case it exposes — the case-name (e.g. “unregistered house pre-first-registration”) plus the minimum data needed to make that case concrete. Two Exemplars are the same Exemplar only if they expose the same named hard case with byte-identical content. See the Logical tier → for the field-level shape.

  • Generator Run — the build pipeline emits Exemplars alongside the ontology TTLs, paired so every emission is reproducible from a recorded (version, commit) pair
  • Validation Context — overlay profiles are validated against Exemplars before the profile is ratified
%%{init: {"theme": "base"}}%% flowchart LR accTitle: Diagnostic Exemplar related-Kinds neighbourhood graph accDescr: Diagnostic Exemplar as a Council-validation receipt; emitted by a Generator Run; used by a Validation Context to confirm an Identity Criterion handles its named hard case. classDef centre fill:#E1BEE7,stroke:#6A1B9A,stroke-width:3px,color:#4A148C classDef cls fill:#B3E5FC,stroke:#0277BD,stroke-width:2px,color:#01579B Exemplar["DiagnosticExemplar
(per named hard case)"]:::centre Run["GeneratorRun"]:::cls VC["ValidationContext"]:::cls Run -->|"emits alongside TTLs"| Exemplar VC -->|"validatedAgainst"| Exemplar

Source ODR

ODR-0004 — PDTF ontology foundation §8a

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