Primitive: one of the library schemas <kind>.schema.json, each exactly { "type": <kind> } (for example string or boolean). It is the canonical, content-addressed block for a kind. A field says what it is by naming one: { "type": "hm://…/string" } names the kind and references that block at once, with the same key that names any other schema. A primitive is an instance of the meta-schema. A variant is different: it is a shape in the union that makes up the meta-schema. The data model lists the kinds.

See also

Kind: the nine value types.

The data model: what each kind holds.

Scalar schema: a kind narrowed by constraints.

Include schema: how naming a schema with type works.

String: one primitive's page.