Definition of "coordinate metadata" - "coordinate epoch"

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.

"coordinate_metadata": {
  "type": "object",
  "properties": {
    "$schema" : { "type": "string" },
    "type": { "type": "string", "enum": ["CoordinateMetadata"] },
    "crs": { "$ref": "#/definitions/crs" },

"coordinateEpoch": { "type": "number" }

  },
  "required" : [ "crs" ],
  "additionalProperties": false
},

"$comment": "[RL] coordinate epoch is mandatory for a coordinate set reference to a dynamic reference frame (datum)."

Start with the coordinate_metadata schema shown in this issue and compare it with the linked ProjJson v0-7 document. Clarify the definition and whether coordinateEpoch is mandatory for dynamic reference frames; done requires an agreed decision and corresponding schema or specification update.