The map type is a core type: a map whose keys are data, where each value matches the values schema. When the keys are known field names, use a struct instead. Its formal schema is attached as the schemaDefinition in this document's metadata, so the app can show it and create values of this type.

See also

struct: a map with known, named fields.

Map schema: how a schema constrains the values.

Example: Counts: a map in use.

Data model: all the kinds.