Definition of "projected_crs"

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.

"projected_crs": {
"type": "object",

"allOf": [{ "$ref": "#/definitions/object_usage" }],

  "properties": {
    "type": { "type": "string",
              "enum": ["ProjectedCRS"] },
    "name": { "type": "string" },
    "base_crs": { "$ref": "#/definitions/geodetic_crs" },
    "conversion": { "$ref": "#/definitions/conversion" },

"coordinate_system": { "$ref": "#/definitions/coordinate_system" }, STRIKE THIS LINE
"coordinate_system": { "$ref": "#/definitions/affine_cs" },

    "$schema" : {},

"scope": {},
"area": {},
"bbox": {},
"vertical_extent": {},
"temporal_extent": {},
"usages": {},

    "remarks": {},
    "id": {}, "ids": {}
 },
 "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
 "additionalProperties": false
},

"$comment": "[RL] See comment regarding usage under compound_crs."

"$comment": "[RL] A projected CRS should be constrained to having an affine_cs. Most projected CRSs will have a Cartesian CS. A Cartesian CS is a subtype of affine CS."

"$comment": "[RL] Does this permit a projected CRS to have a derived geodetic CRS as its base CRS?"

Start by reading the projected_crs definition in this issue and the referenced ProjJson v0-7 RL 2024-06-16.docx. Review the proposed allOf, affine_cs, usage fields, and base CRS question; done means the definition is agreed and the schema and related comments consistently reflect that decision.