Definition of "geodetic_reference_frame"

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.

"geodetic_reference_frame": {
  "type": "object",

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

  "properties": {
    "type": { "type": "string", "enum": ["GeodeticReferenceFrame"] },
    "name": { "type": "string" },
    "anchor": { "type": "string" },
    "anchor_epoch": { "type": "number" },
    "conventional_RS: { "type": "string" }
    "publication_date: { "type": date }
    "ellipsoid": { "$ref": "#/definitions/ellipsoid" },
    "prime_meridian": { "$ref": "#/definitions/prime_meridian" },
    "$schema" : {},

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

    "remarks": {},
    "id": {}, "ids": {}
  }, 

"required" : [ "name", "ellipsoid", "prime_meridian" ],

  "additionalProperties": false
},

"$comment": "[RL] 2x attributes missing."

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

"$comment": "[RL] Topic 2 requires prime meridian as an attribute of geodetic reference frame but WKT2 makes it optional on the condition that value = the international reference meridian (Greenwich).

Note: WKT2 has prime meridian as a direct attribute of a geodetic CRS (for backward compatibility with WKT1) but the modelling here of prime meridian being an attribute of a geodetic reference frame follows 19111/Topic 2."

"$comment": "[RL] In 19111/Topic 2 ellipsoid is an optional attribute of geodetic reference frame (because an ellipsoid is not necessary if working exclusively in geocentric Cartesian coordinates) but WKT2 makes it mandatory (to ensure it is available for conversion to ellipsoidal coordinates)."

Start with the current geodetic_reference_frame definition and the linked ProjJson v0-7 RL 2024-06-16.docx. Compare the proposed attributes, usage fields, required properties, and comments with Topic 2 and WKT2, then document the agreed definition and validation requirements.