Web Vocabularies

Web vocabularies are the type and concept systems used by AI assistants, search engines, and structured-data crawlers to label real-world entities on the public web. World Of Taxonomy hosts the type-tree subset of these vocabularies (the part that is enumerated and hierarchical, per the Inclusion Policy). Property and relation vocabularies are out of scope.

schema.org

schema.org publishes a vocabulary of types and properties that web pages and APIs use to mark up structured data so search engines and AI assistants can understand what a page is about. WoT ingests the type tree only:

• Rooted at Thing. Every type is a subclass of Thing (transitively).
• ~926 types organized via rdfs:subClassOf chains (CreativeWork, Person, Place, Action, etc.).
• ~57 types have multiple parents; WoT keeps the first listed parent as the canonical hierarchy edge and notes the alternative parents in the description.
• 100% description coverage native to the source (every class has rdfs:comment).

Why this matters for AEO and SEO: schema.org type tags are the single most important signal AI search overviews, ChatGPT browsing, and Google Knowledge Graph use to identify what a page is about. Hosting the full type tree in WoT means downstream products (WoO agent runtime, classification/crosswalk APIs) can cite schema.org URIs natively as the canonical anchor for "what kind of thing is this." It also enables crosswalks between schema.org types and domain classifications: schema:Restaurant to NAICS 7225, schema:Hotel to NAICS 7211, schema:MedicalSpecialty to MeSH, and so on.

What WoT does not host: the ~1,676 schema.org rdf:Property entries (name, address, priceRange, etc.) are property definitions, not classification categories. Per the inclusion policy, pure property vocabularies are out of scope. Consumers who need the full property surface should hit schema.org directly.

Related vocabularies in WoT

These sit alongside schema.org as web-adjacent classification systems with smaller coverage than the schema.org type tree.

What's not yet ingested

The following web-vocabulary candidates have been audited against the inclusion policy and are queued for follow-up PRs:

• WordNet hypernym tree (~82K synsets) - lexical semantic anchor.
• DBpedia ontology (~700 classes) - Wikipedia-derived class hierarchy.
• SUMO / BFO / DOLCE - upper ontologies (small, peripheral relevance).
• FOAF classes, DCMI Type Vocabulary - small auxiliary vocabularies.

The full Wikidata Q-number space (~100M entities) and the DBpedia instance set (~5M) are entity registries above WoT's size cap and out of scope. They belong in a sister product (a hypothetical "World of Registries" or directly inside WoO).

How to use schema.org from WoT

# Look up a specific schema.org type
GET /api/v1/systems/schema_org/nodes/Restaurant

# Browse children of CreativeWork
GET /api/v1/systems/schema_org/nodes/CreativeWork/children

# Search across the type tree
GET /api/v1/search?q=medical&systems=schema_org

# Crosswalk to a domain classification (when wired)
GET /api/v1/systems/schema_org/nodes/Restaurant/equivalences

The MCP server exposes the same data via get_industry, browse_children, and search_classifications tools, so AI assistants can resolve a schema.org type to its WoT counterparts without leaving the chat.

Related reading

• Inclusion Policy - the four tests every WoT system must pass.
• Crosswalk Map - how systems connect via equivalence edges.
• Categories and Sectors - how WoT organizes its catalog.