Consume the ontology

The practical guide for a machine consumer of the schema-derived ontology: which prefixes and namespaces to bind, how to query the graph, how the IRIs dereference, how to validate your own data against the shapes, and where to download the Turtle. Everything here is against the committed corpus — the same TTLs the published reference is generated from.

Prefix & namespace map

Bind these prefixes to read or query the ontology. The OPDA terms split across four kind-keyed namespaces (ADR-0006, as-built): terms, schemes, shapes, and the named graphs each live under their own path beneath opda.org.uk/pdtf/. The remaining prefixes are the standard external vocabularies the model reuses (referenced, not imported — see Decision provenance).

The kind-split (separate /, /scheme/, /shape/, /graph/, /harness/ paths) is the ADR-0006 as-built decision; it is what keeps a class IRI, the SKOS scheme that types its values, and the SHACL shape that constrains it from colliding in one flat namespace.

Runnable SPARQL

Run these against a triplestore loaded with opda-merged.ttl (the GRLC API over Fuseki via make serve-data exposes the same graph at http://localhost:3031/opda/sparql). Both queries use real terms from the corpus.

1 — list every OWL class with its label and source provenance:

PREFIX opda: <https://opda.org.uk/pdtf/>
PREFIX owl:  <http://www.w3.org/2002/07/owl#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX dct:  <http://purl.org/dc/terms/>

SELECT ?class ?label ?source WHERE {
  ?class a owl:Class .
  OPTIONAL { ?class rdfs:label ?label }
  OPTIONAL { ?class dct:source ?source }
}
ORDER BY ?class

2 — find the substantive (Category-G) leaves a form's overlay profile binds — here the BASPI5 profile, walking from each property shape to its constrained path:

PREFIX sh:   <http://www.w3.org/ns/shacl#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>

SELECT ?shape ?targetClass ?path ?datatype WHERE {
  ?shape a sh:NodeShape ;
         sh:targetClass ?targetClass ;
         sh:property ?p .
  ?p sh:path ?path .
  OPTIONAL { ?p sh:datatype ?datatype }
}
ORDER BY ?targetClass ?path

The second query reads the shapes graph (opda-shapes-merged.ttl); SHACL Play! renders the same constraints as readable tables on the bake-off page.

Dereferenceability & content negotiation

OPDA term IRIs are HTTPS, under a single registered authority (opda.org.uk/pdtf/…), so they are designed to be dereferenceable: a term IRI is a real, resolvable web address rather than an opaque identifier. The intended contract is standard linked-data content negotiation —

• Accept: text/turtle (or application/rdf+xml, application/ld+json) returns the machine description of the term;
• Accept: text/html returns the human-readable reference page.

The LeaseTerm class and leaseTerm property keep their exact source-model identifiers but use distinct lowercase, type-scoped static representation paths.

Until the production endpoint serves negotiated representations, the authoritative machine artefacts are the committed Turtle bundles linked under TTL downloads below — load those into your own store and the IRIs resolve locally. Note the one open caveat: the ODR-0004 prose still cites the old w3id.org/opda/# namespace, but the emitted TTL uses opda.org.uk/pdtf/ (the as-built namespace in the map above) — see Known issues.

SHACL-validation recipe

To validate your own PDTF instance data against the OPDA shapes, load three graphs into the validator and run pyshacl with advanced=True:

1. the class graph (opda-merged.ttl — the OWL + SKOS TBox, so shape→class labels resolve);
2. the shapes graph (opda-shapes-merged.ttl — the node / property shapes);
3. the relevant overlay-profile graph (e.g. profiles/baspi5.ttl — the per-form Category-G bindings).

pip install pyshacl

pyshacl \
  --shacl opda-shapes-merged.ttl \
  --ont-graph opda-merged.ttl \
  --advanced \
  --format human \
  my-instance-data.ttl

Or in Python — note advanced=True is required, not optional:

from pyshacl import validate

conforms, report_graph, report_text = validate(
    data_graph="my-instance-data.ttl",
    shacl_graph="opda-shapes-merged.ttl",
    ont_graph="opda-merged.ttl",
    advanced=True,          # REQUIRED — see below
    inference="none",
)
print(conforms)
print(report_text)         # read the sh:ValidationReport

TTL downloads

The authoritative machine artefacts, generated from the committed corpus:

• opda-merged.ttl — the merged TBox (OWL classes & properties + SKOS concept schemes). Load this as the --ont-graph for validation and as the data graph for the class queries above.
• opda-shapes-merged.ttl — the merged SHACL shapes graph (node / property shapes + overlay profiles). This is the --shacl graph.
• source/ — the per-module TTLs — the 25 source files (classes, properties, shapes, annotations, vocabularies, contexts, the foundation graph) before merge, for consumers who want a single layer rather than the bundle.

Related: Decision provenance (why the namespaces split the way they do), Known issues (the validation and namespace caveats), and the Tool bake-off (SHACL Play! renders the shapes graph as tables).