Definition of "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.

"crs": {
  "oneOf": [
    { "$ref": "#/definitions/bound_crs" },
    { "$ref": "#/definitions/compound_crs" },
    { "$ref": "#/definitions/derived_engineering_crs" },
    { "$ref": "#/definitions/derived_geodetic_crs" },

{ "$ref": "#/definitions/derived_geographic_crs" },

    { "$ref": "#/definitions/derived_parametric_crs" },
    { "$ref": "#/definitions/derived_projected_crs" },
    { "$ref": "#/definitions/derived_temporal_crs" },
    { "$ref": "#/definitions/derived_vertical_crs" },
    { "$ref": "#/definitions/engineering_crs" },
    { "$ref": "#/definitions/geodetic_crs" },

{ "$ref": "#/definitions/geographic_crs" },

    { "$ref": "#/definitions/parametric_crs" },
    { "$ref": "#/definitions/projected_crs" },
    { "$ref": "#/definitions/temporal_crs" },
    { "$ref": "#/definitions/vertical_crs" }
  ]
},

"$comment": "[RL] 2x CRS subtypes possibly missing?? See comment under geodetic_crs."

"$comment": "[RL] the concept of bound_crs is not recognised in Topic 2 (18-005r8) but it is defined in CRS WKT (18-010r11)(for backward compatibility of WKT2 with some flavors of WKT1). Should it (and abridged_transformation) be included in CRS JSON?"

Start with the linked ProjJson v0-7 document and the crs definition's oneOf list. Compare the missing CRS subtypes and the questions about bound_crs and abridged_transformation with the cited Topic 2 and CRS WKT specifications; done requires an agreed decision on the schema contents.