Composition¶

Composition is how an OO-LD schema builds a complex type from several independent schemas - for example attaching a geolocation schema and a contact schema to one resource type - without needing a shared parent class. Each referenced schema contributes both its JSON Schema properties (via $ref) and its JSON-LD term mappings (via @context).

The key idea: every $ref is reflected into the @context so the composed schema stays usable as a JSON-LD context with no post-processing. A $ref inside a type: object property becomes a property-scoped context; other $refs are listed at the root. When several contexts define the same term, a most-recently-defined-wins rule applies.

For the full normative rules - the reflection rules, oneOf/anyOf handling, type- and property-scoped contexts, @propagate/@protected, base-URI alignment, and the Merge and override model - with worked examples, see Composition in the specification.