Definition of "extent"

NOTE: Markdown does not support highlighting in color, so bold/italic has been used to highlight the material being discussed. This issue is extracted from the document submitted by Roger Lott at https://github.com/opengeospatial/CRS-JSON-Encoding/blob/main/ProjJson%20v0-7%20RL%202024-06-16.docx for discussion at the CRS SWG meeting OGC held during the Montreal June 2024 TC meeting.

"extent": {
    "type": "array",
    "items": {
      "type": "object",
      "properties": {

"extent_description": { "type": "string" },

        "bbox": { "$ref": "#/definitions/bbox" },
        "extent_polygon": { "type": "array" },
        "vertical_extent": { "$ref": "#/definitions/vertical_extent" },
        "temporal_extent": { "$ref": "#/definitions/temporal_extent" }
       },

"required" : [ "extent_description", "bbox" ],

      "additionalProperties": false
    }
},

"$comment": "[RL] In ISO 19111 [OGC Abstract Spec Topic 2](from ISO 19115 [OGC Abstract Spec Topic 11]) an extent must contain at least one of the above properties; it may contain any or all of these properties. In ISO 19127 (geodetic registry) this is specialised: a description and a bbox are made mandatory, the remaining properties are optional. If this is considered best practice for geodetic registries, should it be considered as appropriate for CRS JSON?"

Start with the extent schema excerpt in this issue and the linked ProjJson v0-7 RL 2024-06-16.docx, then review the cited ISO 19111 and ISO 19127 requirements. Resolve whether extent_description and bbox should be mandatory in CRS JSON, and record the agreed schema change or rationale.