Grounding the test fixture in SDG — a requirements-driven recommendation for Aegir

Status: Atelier-side rewire shipped (GT.* retired, SDG.* emitted, sdg_requirements.json produced); awaiting Aegir adoption.

Status: recommendation. Built and extended in Atelier; handed to Aegir, which owns SDG, to adopt or refine.

Why

The test-gittables fixture previously carried an invented GT.* namespace (retired 2026-05-31) — it would have been the fifth overlapping governance vocabulary alongside sdg:, SIGDG:, atelier-vocab.ttl, and signals’ GDC.*. Inventing a sixth dilutes the refinement effort; the fix was to iterate on the one shared surface, the Signals Data Governance ontology (sdg:, Aegir’s src/aegir/ontology/sdg-vocab.ttl, BFO 2020 + CCO grounded). The fixture builder now emits SDG.*-grounded terms instead of GT.*. See [feedback_iterate_shared_sdg_surface] and cco-coverage.

SDG already fits — the property map

SDG is property-centric and reuses CCO’s ICE classes (sdg:identifies, sdg:hasValueType, sdg:hasIdentifier all rdfs:domain cco:DesignativeICE). Every axis the fixture encodes is already an SDG property — we were reinventing them as GT.*:

So the CTA-vs-CPA distinction we encoded as GT.CUR.CURRENCY vs GT.REL.CURRENCY is, in SDG, the same ICE sdg:hasValueType currency vs sdg:describesProperty currency — one surface, two properties.

The grounding model (replaces GT.*)

A fixture leaf is not a new code; it is an SDG-grounded term:

• the column is a cco:InformationContentEntity (Designative or Descriptive — the ICE trichotomy we already carry as ice_class);
• its referent CCO module is the existing cco_module axis;
• a CTA leaf is a value type (sdg:hasValueType <term>), a CPA leaf is a relation (sdg:describesProperty <term>);
• the concrete <term> is sdg:-namespaced, with the DBpedia IRI as dcterms:source / our definition_source and cco:acronym from the mnemonic — the CCO annotations we already emit;
• the unit is sdg:hasUnit, left unfilled where unresolved — i.e. our unit: UNRESOLVED absence is an unfilled sdg:hasUnit / cco:has_token_unit.

Net: the fixture stops minting GT.* and instead instantiates SDG value types + relations, grounded in CCO. The taxonomy becomes a test-scoped subset of SDG, and building it is an SDG coverage audit.

Requirements for Aegir (adopt or refine)

The fixture needs concrete sdg: terms for the types/relations it exercises. These are the requirements — proposed as SDG extensions for Aegir to adopt or reshape:

1. Value-type terms for the GitTables CTA types covering 9 CCO modules (e.g. length, weight, currency, country, author, date, …) as sdg:hasValueType ranges, each grounded in its CCO module + DBpedia IRI.
2. Relation terms for the SOTAB CPA relations (author, publisher, publicationDate, currency, price, …) as sdg:describesProperty ranges (Extended Relation data face).
3. sdg:hasUnit resolution path — the unresolved-unit case (the only un-covered CCO module, Units of Measure) needs an EAV/unit producer to fill sdg:hasUnit; until then it is a positively-represented absence, not a silent gap. This is the highest-priority refinement.
4. Namespace reconciliation — pick sdg: as canonical and retire/redirect SIGDG:, atelier-vocab.ttl, and GDC.* so the surface stops forking.

Plan

1. DONE — Rewired the fixture builder to emit SDG-grounded terms (CCO-module referent + sdg:hasValueType / sdg:describesProperty + DBpedia source), retiring GT.*. Unmapped types are recorded as SDG-coverage gaps.
2. DONE — Emits a machine-readable sdg_requirements.json from the build — the exact value-type/relation terms the fixture needs — as the artifact Aegir consumes.
3. Aegir adopts/refines into sdg-vocab.ttl + catalogs; Atelier re-consumes. (Pending — awaiting Aegir adoption.)