Investigation notes - current OwlUnit + RdfParserUnit baseline vs RDF 1.2

EXPORT SIDE (OwlUnit, 0002232:0001916 lines, single ExportOWL entry point)

• Serialisation: RDF/XML only, string-stitched into a TStringList and written via SaveToUtf8File. An IXMLDocument is created and then unused.
• Namespaces declared up front: rdf, rdfs, owl, xsd, dc, dcterms, skos, swrl plus four OWL-S namespaces (profile, grounding, process, service) and daml that are NEVER referenced in the body - dead declarations from an abandoned experiment, worth removing.
• Datatypes: DataTypeMap routes through dbdmd.RetrieveDataType("XML", ...) to xsd:* (string/date/time/integer/boolean/decimal/dateTimeStamp/hexBinary, plus owl:rational/owl:real). xsd: is rewritten to the full XMLSchema# IRI at output.
• Literals are language-tagged via xml:lang. BUG: the region subtag is stripped (en-US -> en) at lines 511-512, 575-576 and elsewhere. RDF 1.2 supports full BCP 47 - the strip is lossy.
• Multi-locale support is gated on Features.MultiLocale; each translation walked from Translations.Sections.
• OWL 2 idioms already present: owl:Restriction with owl:minCardinality/owl:maxCardinality (xsd:nonNegativeInteger), owl:hasKey rdf:parseType="Collection", owl:oneOf as rdf:first/rdf:rest cons-lists, owl:unionOf rdf:parseType="Collection".
• CaseTalk-specific data attached as <local:...> annotation properties (AddCustomAttribute) plus a DeclareCustomAnnotations pass to register them. Role readings forced into synthetic <local:Incoming rdf:ID="in..."/> + <local:Outgoing rdf:ID="out..."/> resources - a hand-rolled reification because RDF 1.1 has no clean way to attach metadata to a triple.
• Optional SKOS mixin (mixSKOS): skos:inScheme, skos:definition, skos:note, skos:example, skos:prefLabel.

PARSER SIDE (RdfParserUnit, 93 lines, TRDFParser)

• Single regex: ^<...>\s+<...>\s+(<...>|"...")\s.\s$ - strict N-Triples ONLY.
• No datatyped literals ("5"^^xsd:integer), no language tags ("hi"@en), no blank nodes (:b), no comments, no Turtle prefixes, no escape handling, no multi-line. Triple is (Subject, Predicate, Object) as bare strings.
• Effectively a toy - will not round-trip its own export (export is RDF/XML, parser only reads NT).

RDF 1.2 SHIFTS RELEVANT TO CASETALK

• Triple terms (<<:s :p :o>>) become first-class objects. Direct replacement for our synthetic local:Incoming/local:Outgoing rdf:ID reification - attach role-reading metadata to the triple itself.
• Base direction on language strings ("text"@en--ltr / --rtl) and rdf:dirLangString datatype.
• Quoted vs asserted triples distinction (model-level, not syntactic).
• BCP 47 language tags fully supported - vindicates removing the en-US -> en strip.
• Triple terms have no idiomatic RDF/XML syntax - they are Turtle/TriG/N-Quads-native. A Turtle export is the natural vehicle for adopting RDF 1.2.

PROPOSED FOLLOW-UPS (split into separate tickets once scope is agreed)

1. Add a Turtle (.ttl) export path next to the RDF/XML path. Reuse the structural logic in OwlUnit; only change the serialiser.
2. Replace the local:Incoming/Outgoing reification with RDF 1.2 triple terms in the Turtle path - keep the RDF/XML path unchanged for tooling that still consumes 1.1.
3. Stop stripping the language-tag region (full BCP 47).
4. Drop the dead OWL-S / daml namespace declarations.
5. Decide what RdfParserUnit is for. If it is meant to import RDF, upgrade it to a real Turtle/RDF 1.2 parser (Jena is already shipped under Tools/jena and can preprocess to NT via riot if a Delphi rewrite is too costly). If it is dead code, remove it.
6. Add a few RDF 1.2 datatypes to DataTypeMap (rdf:dirLangString and friends).

Out of scope here: SHACL/ShEx export, named-graph framing - those are RDF-stack improvements but not what the email asked about.

Refinement: existing Turtle templates - consolidate, do not reinvent

The codebase already ships two Turtle/RDF export templates under develop/modules/templates/:

1. ttl.ini ("Turtle (TTL)", 442 lines) - most polished. Emits @prefix rdf/rdfs/owl/xsd/skos/dcterms/foaf/vann/cc/schema/dbo. Sections cover ontology metadata, classes from Tables, subtypes from FKs, datatype properties from Columns, object properties from FKs, SKOS concept schemes from value-constrained Domains, OWL restrictions (cardinality, allValuesFrom + oneOf), annotation-property declarations, Schema.org alignment heuristics, VoID dataset, PROV-O provenance. Includes table.Verbalization -> :factExpressions / :businessRules triple-string annotations. Visible bugs: unbalanced parens in Schema.org alignment block, @(schema.Tables).Count emitted mid-Turtle as a literal.

2. ig_turtle_export.ini ("Turtle Export", 352 lines) - less polished but multi-artefact: ontology + SHACL shapes + per-table instance file + SPARQL query examples. Uses a dedicated tmg: namespace ([url=http://casetalk.com/tmg/schema" rel="noopener]http://casetalk.com/tmg/schema[/url]#) for CaseTalk-specific predicates - much cleaner namespace design than ttl.ini's bare :hasArtificialKey style.

Scope vs OwlUnit: both templates walk schema.Tables/Columns/ForeignKeys/Domains - the derived relational schema, not the conceptual TMG. They cannot see OTFTs/ExpRels/Roles natively; they only get FCOIM content via table.Verbalization. OwlUnit goes straight at TMG and exports OTFTs, expressions and role readings.

Revised plan

• Keep OwlUnit as the OTFT-level RDF/XML export (the conceptual-model surface).
• Consolidate ttl.ini and ig_turtle_export.ini into a single canonical Turtle template: keep ig_turtle_export.ini's tmg: namespace design, fold in ttl.ini's PROV-O/VoID/annotation-property declarations, fix the parens and the @(...).Count escape, retire the duplicate.
• Adopt RDF 1.2 inside the Turtle template (not in OwlUnit): replace synthetic :factExpressions string annotations with triple terms (<<:Customer :hasReading "Customer places Order">> :assertedBy :CaseTalk), stop hard-coding @en (use database.Locale or table.Locale), and emit rdf:dirLangString for RTL locales. Triple terms have no idiomatic RDF/XML, so this is naturally Turtle-only.

This is filed as a follow-up ticket (template consolidation + RDF 1.2 upgrade) so 0005612 can stay as the broader research/audit issue.

Resolved as the audit-and-first-pass is complete. Concrete RDF 1.2 / OwlUnit work shipped in 15.0:

• OwlUnit cleanup (commit 6198eb560): removed the unused IXMLDocument scaffolding and the four Xml.* units it pulled in; pruned seven dead xmlns declarations (profile, grounding, dcterms, swrl, process, service, daml) from the rdf:RDF root. Output narrowed to what is actually emitted: rdf, rdfs, owl, xsd, dc, skos, casetalk, local.
• Turtle export consolidated and brought to RDF 1.2 in 0005614 (commit d93f7a439): ttl.ini retired, ig_turtle_export.ini becomes the canonical Turtle path with PROV-O / VoID / annotation declarations, verbalisations attached via triple terms (<< :C a owl:Class >> tmg:hasFactExpression "..."), SHACL + SPARQL companions.
• Investigation notes for OwlUnit and RdfParserUnit captured on this ticket - the inventory of what the export currently emits, what is broken, and where RDF 1.2 unlocks cleaner idioms.

Deferred (not blocking 15.0; open new tickets when scheduling):

• Stop stripping the BCP 47 region from the language tag in OwlUnit (en-US -> en).
• Replace OwlUnit's synthetic local:Incoming / local:Outgoing role-reading reification with triple terms in a future Turtle path inside OwlUnit (the .ini template covers the schema-level Turtle output; OwlUnit still emits OTFT-level RDF/XML only).
• RdfParserUnit is still NT-only. Decide whether to upgrade to a real Turtle/RDF 1.2 parser (Jena under Tools/jena can be shelled out as a preprocessor) or remove as dead code.
• A few RDF 1.2 datatypes (rdf:dirLangString and friends) for DataTypeMap.

The current OWL/RDF in XML notation should be extended to also allow RDF 1.2 output which makes reification obsolete.

<rdf:RDF xmlns:rdf="[url=http://www.w3.org/1999/02/22-rdf-syntax-ns" rel="noopener,nofollow]http://www.w3.org/1999/02/22-rdf-syntax-ns[/url]#"
xmlns:foaf="[url=http://xmlns.com/foaf/0.1/" rel="noopener,nofollow]http://xmlns.com/foaf/0.1/[/url]">

<rdf:Description rdf:about="[url=http://example.org/bob" rel="noopener,nofollow]http://example.org/bob[/url]">
<foaf:name>Bob</foaf:name>
<foaf:knows rdf:resource="[url=http://example.org/alice" rel="noopener,nofollow]http://example.org/alice[/url]"/>
</rdf:Description>
<rdf:Description rdf:about="[url=http://example.org/alice" rel="noopener,nofollow]http://example.org/alice[/url]">
<foaf:name>Alice</foaf:name>
</rdf:Description>
</rdf:RDF>

RDF (without the star) is an abstract knowledge representation model that does not differentiate data from metadata. It provides enormous flexibility for the expression of multiple levels of metadata about nodes, classes, predicates (relationship types), and even (sub-)graphs.

Examples[/url" rel="noopener,nofollow]https://www.ontotext.com/knowledgehub/fundamentals/what-is-rdf-star/]Examples[/url]