Definition of "usages" and "usage"

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.

"usages": {
    "type": "array",
    "items": {
      "type": "object",
      "properties": {
        "scope": { "type": "string" },
        "area": { "type": "string" },
        "bbox": { "$ref": "#/definitions/bbox" },
        "vertical_extent": { "$ref": "#/definitions/vertical_extent" },
        "temporal_extent": { "$ref": "#/definitions/temporal_extent" }
       },
      "additionalProperties": false
    }
},

"$comment": "[RL] In ISO 19111 a usage must contain one scope and one extent. (See below for extent). The main geodetic entities (CRS, datum, all types of coordinate operation) should have at least one and may have many usages. Should the schema be something like Usage below?"

"usage": {
    "type": "array",
    "items": {
      "type": "object",
      "properties": {
        "scope": { "type": "string" },
        "extent": { "$ref": "#/definitions/extent" },
       },
"required" : [ "scope", "extent" ],
      "additionalProperties": false
    }
},

"$comment": "[RL]In ISO 19111 a usage is optional but (in §8.1.4) at least one usage is recommended. If this is considered best practice for geodetic registries, should the cardinality of Usage in CRS JSON be 1:* ?"

Start with the linked ProjJson v0-7 document and the schema examples in this issue, then review the cited ISO 19111 requirements. Resolve how “usages” and “usage” should be defined, including required scope and extent fields and cardinality; done means the specification has an agreed schema and terminology.