$schema: https://json-schema.org/draft/2020-12/schema
description: 'A Ring feature: an ordered closed loop of directed (oriented) Edge references
  forming a boundary. geometry must be null. Uses directed_references (not references)
  in its topology.'
allOf:
- $ref: https://ogcincubator.github.io/topo-feature/build/annotated/geo/topo/features/topo-feature/schema.yaml
- properties:
    geometry:
      type: 'null'
    circumference:
      type: number
      x-jsonld-id: topo:circumference
    topology:
      properties:
        type:
          type: string
          const: Ring
        directed_references:
          type: array
          description: Ordered list of oriented Edge references forming the closed
            ring boundary
          items:
            $ref: https://ogcincubator.github.io/topo-feature/build/annotated/geo/topo/datatypes/oriented-ref/schema.yaml
          minItems: 3
      required:
      - type
      - directed_references
      not:
        required:
        - references
  required:
  - topology