From cad1c5cf61fc00759bf4ad17b0b34f57f4945de6 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Sat, 17 Aug 2019 10:58:08 +0200
Subject: PROJJSON: rename file as projjson.schema.json, and add versionning to
 it and to exported PROJJSON strings

---
 data/Makefile.am          |   4 +-
 data/crsjson.schema.json  | 935 --------------------------------------------
 data/projjson.schema.json | 972 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 974 insertions(+), 937 deletions(-)
 delete mode 100644 data/crsjson.schema.json
 create mode 100644 data/projjson.schema.json

(limited to 'data')

diff --git a/data/Makefile.am b/data/Makefile.am
index 096ba7c3..d686270d 100644
--- a/data/Makefile.am
+++ b/data/Makefile.am
@@ -3,7 +3,7 @@ DATAPATH = $(top_srcdir)/data
 pkgdata_DATA = GL27 nad.lst nad27 nad83 world other.extra \
 		CH null \
 		ITRF2000 ITRF2008 ITRF2014 proj.db \
-		crsjson.schema.json
+		projjson.schema.json
 
 SQL_ORDERED_LIST = sql/begin.sql \
 		sql/proj_db_table_defs.sql \
@@ -41,7 +41,7 @@ EXTRA_DIST = GL27 nad.lst nad27 nad83 \
 		world other.extra \
 		CH \
 		ITRF2000 ITRF2008 ITRF2014 \
-		crsjson.schema.json \
+		projjson.schema.json \
 		CMakeLists.txt tests/test_nodata.gtx null \
 		generate_all_sql_in.cmake sql_filelist.cmake \
 		$(SQL_ORDERED_LIST)
diff --git a/data/crsjson.schema.json b/data/crsjson.schema.json
deleted file mode 100644
index 726d8ece..00000000
--- a/data/crsjson.schema.json
+++ /dev/null
@@ -1,935 +0,0 @@
-{
-  "$id": "https://proj.org/crsjson.schema.json",
-  "$schema": "http://json-schema.org/draft-07/schema#",
-  "description": "Schema for CRS JSON",
-
-  "oneOf": [
-    { "$ref": "#/definitions/crs" },
-    { "$ref": "#/definitions/datum" },
-    { "$ref": "#/definitions/datum_ensemble" },
-    { "$ref": "#/definitions/ellipsoid" },
-    { "$ref": "#/definitions/prime_meridian" },
-    { "$ref": "#/definitions/single_operation" },
-    { "$ref": "#/definitions/concatenated_operation" }
-  ],
-
-  "definitions": {
-
-    "abridged_transformation": {
-      "type": "object",
-      "properties": {
-        "type": { "type": "string", "enum": ["AbridgedTransformation"] },
-        "name": { "type": "string" },
-        "method": { "$ref": "#/definitions/method" },
-        "parameters": {
-            "type": "array",
-            "items": { "$ref": "#/definitions/parameter_value" }
-        },
-        "id": { "$ref": "#/definitions/id" },
-        "ids": { "$ref": "#/definitions/ids" }
-      },
-      "required" : [ "name", "method", "parameters" ],
-      "allOf": [
-        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-      ],
-      "additionalProperties": false
-    },
-
-    "axis": {
-      "type": "object",
-      "properties": {
-        "type": { "type": "string", "enum": ["Axis"] },
-        "name": { "type": "string" },
-        "abbreviation": { "type": "string" },
-        "direction": { "type": "string",
-                       "enum": [ "north",
-                                 "northNorthEast",
-                                 "northEast",
-                                 "eastNorthEast",
-                                 "east",
-                                 "eastSouthEast",
-                                 "southEast",
-                                 "southSouthEast",
-                                 "south",
-                                 "southSouthWest",
-                                 "southWest",
-                                 "westSouthWest",
-                                 "west",
-                                 "westNorthWest",
-                                 "northWest",
-                                 "northNorthWest",
-                                 "up",
-                                 "down",
-                                 "geocentricX",
-                                 "geocentricY",
-                                 "geocentricZ",
-                                 "columnPositive",
-                                 "columnNegative",
-                                 "rowPositive",
-                                 "rowNegative",
-                                 "displayRight",
-                                 "displayLeft",
-                                 "displayUp",
-                                 "displayDown",
-                                 "forward",
-                                 "aft",
-                                 "port",
-                                 "starboard",
-                                 "clockwise",
-                                 "counterClockwise",
-                                 "towards",
-                                 "awayFrom",
-                                 "future",
-                                 "past",
-                                 "unspecified" ] },
-        "unit": { "$ref": "#/definitions/unit" },
-        "id": { "$ref": "#/definitions/id" },
-        "ids": { "$ref": "#/definitions/ids" }
-      },
-      "required" : [ "name", "abbreviation", "direction" ],
-      "allOf": [
-        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-      ],
-      "additionalProperties": false
-    },
-
-    "bbox": {
-      "type": "object",
-      "properties": {
-        "east_longitude": { "type": "number" },
-        "west_longitude": { "type": "number" },
-        "south_latitude": { "type": "number" },
-        "north_latitude": { "type": "number" }
-      },
-      "required" : [ "east_longitude", "west_longitude",
-                     "south_latitude", "north_latitude" ],
-      "additionalProperties": false
-    },
-
-    "bound_crs": {
-      "type": "object",
-      "properties": {
-        "type": { "type": "string", "enum": ["BoundCRS"] },
-        "source_crs": { "$ref": "#/definitions/crs" },
-        "target_crs": { "$ref": "#/definitions/crs" },
-        "transformation": { "$ref": "#/definitions/abridged_transformation" }
-     },
-     "required" : [ "source_crs", "target_crs", "transformation" ],
-     "additionalProperties": false
-    },
-
-    "compound_crs": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["CompoundCRS"] },
-        "name": { "type": "string" },
-        "components":  {
-           "type": "array",
-            "items": { "$ref": "#/definitions/crs" }
-        },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name", "components" ],
-      "additionalProperties": false
-    },
-
-    "concatenated_operation": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["ConcatenatedOperation"] },
-        "name": { "type": "string" },
-        "source_crs": { "$ref": "#/definitions/crs" },
-        "target_crs": { "$ref": "#/definitions/crs" },
-        "steps":  {
-           "type": "array",
-            "items": { "$ref": "#/definitions/single_operation" }
-        },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name", "source_crs", "target_crs", "steps" ],
-      "additionalProperties": false
-    },
-
-    "conversion": {
-      "type": "object",
-      "properties": {
-        "type": { "type": "string", "enum": ["Conversion"] },
-        "name": { "type": "string" },
-        "method": { "$ref": "#/definitions/method" },
-        "parameters": {
-            "type": "array",
-            "items": { "$ref": "#/definitions/parameter_value" }
-        },
-        "id": { "$ref": "#/definitions/id" },
-        "ids": { "$ref": "#/definitions/ids" }
-      },
-      "required" : [ "name", "method" ],
-      "allOf": [
-        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-      ],
-      "additionalProperties": false
-    },
-
-    "coordinate_system": {
-      "type": "object",
-      "properties": {
-        "type": { "type": "string", "enum": ["CoordinateSystem"] },
-        "name": { "type": "string" },
-        "subtype": { "type": "string",
-                     "enum": ["Cartesian",
-                              "spherical",
-                              "ellipsoidal",
-                              "vertical",
-                              "ordinal",
-                              "parametric",
-                              "TemporalDateTime",
-                              "TemporalCount",
-                              "TemporalMeasure"]  },
-        "axis": {
-            "type": "array",
-            "items": { "$ref": "#/definitions/axis" }
-        },
-        "id": { "$ref": "#/definitions/id" },
-        "ids": { "$ref": "#/definitions/ids" }
-      },
-      "required" : [ "subtype", "axis" ],
-      "allOf": [
-        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-      ],
-      "additionalProperties": false
-    },
-
-    "crs": {
-      "oneOf": [
-        { "$ref": "#/definitions/bound_crs" },
-        { "$ref": "#/definitions/compound_crs" },
-        { "$ref": "#/definitions/derived_engineering_crs" },
-        { "$ref": "#/definitions/derived_geodetic_crs" },
-        { "$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/parametric_crs" },
-        { "$ref": "#/definitions/projected_crs" },
-        { "$ref": "#/definitions/temporal_crs" },
-        { "$ref": "#/definitions/vertical_crs" }
-      ]
-    },
-
-    "datum": {
-      "oneOf": [
-        { "$ref": "#/definitions/geodetic_reference_frame" },
-        { "$ref": "#/definitions/vertical_reference_frame" },
-        { "$ref": "#/definitions/dynamic_geodetic_reference_frame" },
-        { "$ref": "#/definitions/dynamic_vertical_reference_frame" },
-        { "$ref": "#/definitions/temporal_datum" },
-        { "$ref": "#/definitions/parametric_datum" },
-        { "$ref": "#/definitions/engineering_datum" }
-      ]
-    },
-
-    "datum_ensemble": {
-      "type": "object",
-      "properties": {
-        "type": { "type": "string", "enum": ["DatumEnsemble"] },
-        "name": { "type": "string" },
-        "members": {
-            "type": "array",
-            "items": {
-                "type": "object",
-                "properties": {
-                    "name": { "type": "string" },
-                    "id": { "$ref": "#/definitions/id" },
-                    "ids": { "$ref": "#/definitions/ids" }
-                },
-                "required" : [ "name" ],
-                "allOf": [
-                    { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-                ],
-                "additionalProperties": false
-            }
-        },
-        "ellipsoid": { "$ref": "#/definitions/ellipsoid" },
-        "accuracy": { "type": "string" },
-        "id": { "$ref": "#/definitions/id" },
-        "ids": { "$ref": "#/definitions/ids" }
-      },
-      "required" : [ "name", "members", "accuracy" ],
-      "allOf": [
-        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-      ],
-      "additionalProperties": false
-    },
-
-    "derived_engineering_crs": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string",
-                  "enum": ["DerivedEngineeringCRS"] },
-        "name": { "type": "string" },
-        "base_crs": { "$ref": "#/definitions/engineering_crs" },
-        "conversion": { "$ref": "#/definitions/conversion" },
-        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-     },
-     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
-     "additionalProperties": false
-    },
-
-    "derived_geodetic_crs": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string",
-                  "enum": ["DerivedGeodeticCRS",
-                           "DerivedGeographicCRS"] },
-        "name": { "type": "string" },
-        "base_crs": { "$ref": "#/definitions/geodetic_crs" },
-        "conversion": { "$ref": "#/definitions/conversion" },
-        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-     },
-     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
-     "additionalProperties": false
-    },
-
-    "derived_parametric_crs": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string",
-                  "enum": ["DerivedParametricCRS"] },
-        "name": { "type": "string" },
-        "base_crs": { "$ref": "#/definitions/parametric_crs" },
-        "conversion": { "$ref": "#/definitions/conversion" },
-        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-     },
-     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
-     "additionalProperties": false
-    },
-
-    "derived_projected_crs": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string",
-                  "enum": ["DerivedProjectedCRS"] },
-        "name": { "type": "string" },
-        "base_crs": { "$ref": "#/definitions/projected_crs" },
-        "conversion": { "$ref": "#/definitions/conversion" },
-        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-     },
-     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
-     "additionalProperties": false
-    },
-
-    "derived_temporal_crs": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string",
-                  "enum": ["DerivedTemporalCRS"] },
-        "name": { "type": "string" },
-        "base_crs": { "$ref": "#/definitions/temporal_crs" },
-        "conversion": { "$ref": "#/definitions/conversion" },
-        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-     },
-     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
-     "additionalProperties": false
-    },
-
-    "derived_vertical_crs": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string",
-                  "enum": ["DerivedVerticalCRS"] },
-        "name": { "type": "string" },
-        "base_crs": { "$ref": "#/definitions/vertical_crs" },
-        "conversion": { "$ref": "#/definitions/conversion" },
-        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-     },
-     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
-     "additionalProperties": false
-    },
-
-    "dynamic_geodetic_reference_frame": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/geodetic_reference_frame" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["DynamicGeodeticReferenceFrame"] },
-        "name": {},
-        "anchor": {},
-        "ellipsoid": {},
-        "prime_meridian": {},
-        "frame_reference_epoch": { "type": "number" },
-        "deformation_model": { "type": "string" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name", "ellipsoid", "frame_reference_epoch" ],
-      "additionalProperties": false
-    },
-
-    "dynamic_vertical_reference_frame": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/vertical_reference_frame" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["DynamicVerticalReferenceFrame"] },
-        "name": {},
-        "anchor": {},
-        "frame_reference_epoch": { "type": "number" },
-        "deformation_model": { "type": "string" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name", "frame_reference_epoch" ],
-      "additionalProperties": false
-    },
-
-    "ellipsoid": {
-      "type": "object",
-      "oneOf":[
-        {
-          "properties": {
-            "type": { "type": "string", "enum": ["Ellipsoid"] },
-            "name": { "type": "string" },
-            "semi_major_axis": { "$ref": "#/definitions/value_in_metre_or_value_and_unit" },
-            "semi_minor_axis": { "$ref": "#/definitions/value_in_metre_or_value_and_unit" },
-            "id": { "$ref": "#/definitions/id" },
-            "ids": { "$ref": "#/definitions/ids" }
-          },
-          "required" : [ "name", "semi_major_axis", "semi_minor_axis" ],
-          "additionalProperties": false
-        },
-        {
-          "properties": {
-            "type": { "type": "string", "enum": ["Ellipsoid"] },
-            "name": { "type": "string" },
-            "semi_major_axis": { "$ref": "#/definitions/value_in_metre_or_value_and_unit" },
-            "inverse_flattening": { "type": "number" },
-            "id": { "$ref": "#/definitions/id" },
-           "ids": { "$ref": "#/definitions/ids" }
-          },
-          "required" : [ "name", "semi_major_axis", "inverse_flattening" ],
-          "additionalProperties": false
-        },
-        {
-          "properties": {
-            "type": { "type": "string", "enum": ["Ellipsoid"] },
-            "name": { "type": "string" },
-            "radius": { "$ref": "#/definitions/value_in_metre_or_value_and_unit" },
-            "id": { "$ref": "#/definitions/id" },
-            "ids": { "$ref": "#/definitions/ids" }
-          },
-          "required" : [ "name", "radius" ],
-         "additionalProperties": false
-        }
-      ],
-      "allOf": [
-        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-      ]
-    },
-
-    "engineering_crs": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["EngineeringCRS"] },
-        "name": { "type": "string" },
-        "datum": { "$ref": "#/definitions/engineering_datum" },
-        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name", "datum" ],
-      "additionalProperties": false
-    },
-
-    "engineering_datum": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["EngineeringDatum"] },
-        "name": { "type": "string" },
-        "anchor": { "type": "string" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name" ],
-      "additionalProperties": false
-    },
-
-    "geodetic_crs": {
-      "type": "object",
-      "properties": {
-        "type": { "type": "string", "enum": ["GeodeticCRS", "GeographicCRS"] },
-        "name": { "type": "string" },
-        "datum": {
-            "oneOf": [
-                { "$ref": "#/definitions/geodetic_reference_frame" },
-                { "$ref": "#/definitions/dynamic_geodetic_reference_frame" }
-            ]
-        },
-        "datum_ensemble": { "$ref": "#/definitions/datum_ensemble" },
-        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name" ],
-      "description": "One and only one of datum and datum_ensemble must be provided",
-      "allOf": [
-        { "$ref": "#/definitions/object_usage" },
-        { "$ref": "#/definitions/one_and_only_one_of_datum_or_datum_ensemble" }
-      ],
-      "additionalProperties": false
-    },
-
-    "geodetic_reference_frame": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["GeodeticReferenceFrame"] },
-        "name": { "type": "string" },
-        "anchor": { "type": "string" },
-        "ellipsoid": { "$ref": "#/definitions/ellipsoid" },
-        "prime_meridian": { "$ref": "#/definitions/prime_meridian" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name", "ellipsoid" ],
-      "additionalProperties": false
-    },
-
-    "id": {
-      "type": "object",
-      "properties": {
-        "authority": { "type": "string" },
-        "code": {
-          "oneOf": [ { "type": "string" }, { "type": "integer" } ]
-        }
-      },
-      "required" : [ "authority", "code" ],
-      "additionalProperties": false
-    },
-
-    "ids": {
-      "type": "array",
-      "items": { "$ref": "#/definitions/id" }
-    },
-
-    "method": {
-      "type": "object",
-      "properties": {
-        "type": { "type": "string", "enum": ["OperationMethod"]},
-        "name": { "type": "string" },
-        "id": { "$ref": "#/definitions/id" },
-        "ids": { "$ref": "#/definitions/ids" }
-      },
-      "required" : [ "name" ],
-      "allOf": [
-        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-      ],
-      "additionalProperties": false
-    },
-
-    "id_ids_mutually_exclusive": {
-        "not": {
-            "type": "object",
-            "required": [ "id", "ids" ]
-        }
-    },
-
-    "one_and_only_one_of_datum_or_datum_ensemble": {
-      "allOf": [
-        {
-            "not": {
-                "type": "object",
-                "required": [ "datum", "datum_ensemble" ]
-            }
-        },
-        {
-            "oneOf": [
-                { "type": "object", "required": ["datum"] },
-                { "type": "object", "required": ["datum_ensemble"] }
-            ]
-        }
-      ]
-    },
-
-    "object_usage": {
-      "anyOf": [
-      {
-        "type": "object",
-        "properties": {
-            "scope": { "type": "string" },
-            "area": { "type": "string" },
-            "bbox": { "$ref": "#/definitions/bbox" },
-            "remarks": { "type": "string" },
-            "id": { "$ref": "#/definitions/id" },
-            "ids": { "$ref": "#/definitions/ids" }
-        },
-        "allOf": [
-            { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-        ]
-      },
-      {
-        "type": "object",
-        "properties": {
-            "usages": { "$ref": "#/definitions/usages" },
-            "remarks": { "type": "string" },
-            "id": { "$ref": "#/definitions/id" },
-            "ids": { "$ref": "#/definitions/ids" }
-        },
-        "allOf": [
-            { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-        ]
-      }
-      ]
-    },
-
-    "parameter_value": {
-      "type": "object",
-      "properties": {
-        "type": { "type": "string", "enum": ["ParameterValue"] },
-        "name": { "type": "string" },
-        "value": {
-          "oneOf": [
-            { "type": "string" },
-            { "type": "number" }
-           ]
-        },
-        "unit": { "$ref": "#/definitions/unit" },
-        "id": { "$ref": "#/definitions/id" },
-        "ids": { "$ref": "#/definitions/ids" }
-      },
-      "required" : [ "name", "value" ],
-      "allOf": [
-        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-      ],
-      "additionalProperties": false
-    },
-
-    "parametric_crs": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["ParametricCRS"] },
-        "name": { "type": "string" },
-        "datum": { "$ref": "#/definitions/parametric_datum" },
-        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name", "datum" ],
-      "additionalProperties": false
-    },
-
-    "parametric_datum": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["ParametricDatum"] },
-        "name": { "type": "string" },
-        "anchor": { "type": "string" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name" ],
-      "additionalProperties": false
-    },
-
-    "prime_meridian": {
-      "type": "object",
-      "properties": {
-        "type": { "type": "string", "enum": ["PrimeMeridian"] },
-        "name": { "type": "string" },
-        "longitude": { "$ref": "#/definitions/value_and_unit" },
-        "id": { "$ref": "#/definitions/id" },
-        "ids": { "$ref": "#/definitions/ids" }
-      },
-      "required" : [ "name" ],
-      "allOf": [
-        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-      ],
-      "additionalProperties": false
-    },
-
-    "single_operation": {
-      "oneOf": [
-        { "$ref": "#/definitions/conversion" },
-        { "$ref": "#/definitions/transformation" }
-      ]
-    },
-
-    "projected_crs": {
-      "type": "object",
-      "allOf": [{ "$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": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-     },
-     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
-     "additionalProperties": false
-    },
-
-    "temporal_crs": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["TemporalCRS"] },
-        "name": { "type": "string" },
-        "datum": { "$ref": "#/definitions/temporal_datum" },
-        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name", "datum" ],
-      "additionalProperties": false
-    },
-
-    "temporal_datum": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["TemporalDatum"] },
-        "name": { "type": "string" },
-        "calendar": { "type": "string" },
-        "time_origin": { "type": "string" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name", "calendar" ],
-      "additionalProperties": false
-    },
-
-    "transformation": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["Transformation"] },
-        "name": { "type": "string" },
-        "source_crs": { "$ref": "#/definitions/crs" },
-        "target_crs": { "$ref": "#/definitions/crs" },
-        "interpolation_crs": { "$ref": "#/definitions/crs" },
-        "method": { "$ref": "#/definitions/method" },
-        "parameters": {
-            "type": "array",
-            "items": { "$ref": "#/definitions/parameter_value" }
-        },
-        "accuracy": { "type": "string" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name", "source_crs", "target_crs", "method", "parameters" ],
-      "additionalProperties": false
-    },
-
-    "unit": {
-      "oneOf": [
-      {
-        "type": "string",
-        "enum": ["metre", "degree", "unity"]
-      },
-      {
-        "type": "object",
-        "properties": {
-          "type": { "type": "string",
-                    "enum": ["LinearUnit", "AngularUnit", "ScaleUnit",
-                             "TimeUnit", "ParametricUnit", "Unit"] },
-          "name": { "type": "string" },
-          "conversion_factor": { "type": "number" },
-          "id": { "$ref": "#/definitions/id" },
-          "ids": { "$ref": "#/definitions/ids" }
-         },
-         "required" : [ "type", "name" ],
-         "allOf": [
-            { "$ref": "#/definitions/id_ids_mutually_exclusive" }
-          ],
-         "additionalProperties": false
-      }
-      ]
-    },
-
-    "usages": {
-        "type": "array",
-        "items": {
-          "type": "object",
-          "properties": {
-            "scope": { "type": "string" },
-            "area": { "type": "string" },
-            "bbox": { "$ref": "#/definitions/bbox" }
-           },
-          "additionalProperties": false
-        }
-    },
-
-    "value_and_unit": {
-      "type": "object",
-      "properties": {
-        "value": { "type": "number" },
-        "unit": { "$ref": "#/definitions/unit" }
-      },
-      "required" : [ "value", "unit" ],
-      "additionalProperties": false
-    },
-
-    "value_in_metre_or_value_and_unit": {
-      "oneOf": [
-        { "type": "number" },
-        { "$ref": "#/definitions/value_and_unit" }
-      ]
-    },
-
-    "vertical_crs": {
-      "type": "object",
-      "properties": {
-        "type": { "type": "string", "enum": ["VerticalCRS"] },
-        "name": { "type": "string" },
-        "datum": {
-            "oneOf": [
-                { "$ref": "#/definitions/vertical_reference_frame" },
-                { "$ref": "#/definitions/dynamic_vertical_reference_frame" }
-            ]
-        },
-        "datum_ensemble": { "$ref": "#/definitions/datum_ensemble" },
-        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name"],
-      "description": "One and only one of datum and datum_ensemble must be provided",
-      "allOf": [
-        { "$ref": "#/definitions/object_usage" },
-        { "$ref": "#/definitions/one_and_only_one_of_datum_or_datum_ensemble" }
-      ],
-      "additionalProperties": false
-    },
-
-    "vertical_reference_frame": {
-      "type": "object",
-      "allOf": [{ "$ref": "#/definitions/object_usage" }],
-      "properties": {
-        "type": { "type": "string", "enum": ["VerticalReferenceFrame"] },
-        "name": { "type": "string" },
-        "anchor": { "type": "string" },
-        "scope": {},
-        "area": {},
-        "bbox": {},
-        "usages": {},
-        "remarks": {},
-        "id": {}, "ids": {}
-      },
-      "required" : [ "name" ],
-      "additionalProperties": false
-    }
-
-  }
-}
diff --git a/data/projjson.schema.json b/data/projjson.schema.json
new file mode 100644
index 00000000..60fca6df
--- /dev/null
+++ b/data/projjson.schema.json
@@ -0,0 +1,972 @@
+{
+  "$id": "https://proj.org/schemas/v0.1/projjson.schema.json",
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "description": "Schema for PROJJSON",
+  "$comment": "This file exists both in data/ and in schemas/vXXX/. Keep both in sync. And if changing the value of $id, change PROJJSON_CURRENT_VERSION accordingly in io.cpp",
+
+  "oneOf": [
+    { "$ref": "#/definitions/crs" },
+    { "$ref": "#/definitions/datum" },
+    { "$ref": "#/definitions/datum_ensemble" },
+    { "$ref": "#/definitions/ellipsoid" },
+    { "$ref": "#/definitions/prime_meridian" },
+    { "$ref": "#/definitions/single_operation" },
+    { "$ref": "#/definitions/concatenated_operation" }
+  ],
+
+  "definitions": {
+
+    "abridged_transformation": {
+      "type": "object",
+      "properties": {
+        "$schema" : { "type": "string" },
+        "type": { "type": "string", "enum": ["AbridgedTransformation"] },
+        "name": { "type": "string" },
+        "method": { "$ref": "#/definitions/method" },
+        "parameters": {
+            "type": "array",
+            "items": { "$ref": "#/definitions/parameter_value" }
+        },
+        "id": { "$ref": "#/definitions/id" },
+        "ids": { "$ref": "#/definitions/ids" }
+      },
+      "required" : [ "name", "method", "parameters" ],
+      "allOf": [
+        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+      ],
+      "additionalProperties": false
+    },
+
+    "axis": {
+      "type": "object",
+      "properties": {
+        "$schema" : { "type": "string" },
+        "type": { "type": "string", "enum": ["Axis"] },
+        "name": { "type": "string" },
+        "abbreviation": { "type": "string" },
+        "direction": { "type": "string",
+                       "enum": [ "north",
+                                 "northNorthEast",
+                                 "northEast",
+                                 "eastNorthEast",
+                                 "east",
+                                 "eastSouthEast",
+                                 "southEast",
+                                 "southSouthEast",
+                                 "south",
+                                 "southSouthWest",
+                                 "southWest",
+                                 "westSouthWest",
+                                 "west",
+                                 "westNorthWest",
+                                 "northWest",
+                                 "northNorthWest",
+                                 "up",
+                                 "down",
+                                 "geocentricX",
+                                 "geocentricY",
+                                 "geocentricZ",
+                                 "columnPositive",
+                                 "columnNegative",
+                                 "rowPositive",
+                                 "rowNegative",
+                                 "displayRight",
+                                 "displayLeft",
+                                 "displayUp",
+                                 "displayDown",
+                                 "forward",
+                                 "aft",
+                                 "port",
+                                 "starboard",
+                                 "clockwise",
+                                 "counterClockwise",
+                                 "towards",
+                                 "awayFrom",
+                                 "future",
+                                 "past",
+                                 "unspecified" ] },
+        "unit": { "$ref": "#/definitions/unit" },
+        "id": { "$ref": "#/definitions/id" },
+        "ids": { "$ref": "#/definitions/ids" }
+      },
+      "required" : [ "name", "abbreviation", "direction" ],
+      "allOf": [
+        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+      ],
+      "additionalProperties": false
+    },
+
+    "bbox": {
+      "type": "object",
+      "properties": {
+        "east_longitude": { "type": "number" },
+        "west_longitude": { "type": "number" },
+        "south_latitude": { "type": "number" },
+        "north_latitude": { "type": "number" }
+      },
+      "required" : [ "east_longitude", "west_longitude",
+                     "south_latitude", "north_latitude" ],
+      "additionalProperties": false
+    },
+
+    "bound_crs": {
+      "type": "object",
+      "properties": {
+        "$schema" : { "type": "string" },
+        "type": { "type": "string", "enum": ["BoundCRS"] },
+        "source_crs": { "$ref": "#/definitions/crs" },
+        "target_crs": { "$ref": "#/definitions/crs" },
+        "transformation": { "$ref": "#/definitions/abridged_transformation" }
+     },
+     "required" : [ "source_crs", "target_crs", "transformation" ],
+     "additionalProperties": false
+    },
+
+    "compound_crs": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["CompoundCRS"] },
+        "name": { "type": "string" },
+        "components":  {
+           "type": "array",
+            "items": { "$ref": "#/definitions/crs" }
+        },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name", "components" ],
+      "additionalProperties": false
+    },
+
+    "concatenated_operation": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["ConcatenatedOperation"] },
+        "name": { "type": "string" },
+        "source_crs": { "$ref": "#/definitions/crs" },
+        "target_crs": { "$ref": "#/definitions/crs" },
+        "steps":  {
+           "type": "array",
+            "items": { "$ref": "#/definitions/single_operation" }
+        },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name", "source_crs", "target_crs", "steps" ],
+      "additionalProperties": false
+    },
+
+    "conversion": {
+      "type": "object",
+      "properties": {
+        "$schema" : { "type": "string" },
+        "type": { "type": "string", "enum": ["Conversion"] },
+        "name": { "type": "string" },
+        "method": { "$ref": "#/definitions/method" },
+        "parameters": {
+            "type": "array",
+            "items": { "$ref": "#/definitions/parameter_value" }
+        },
+        "id": { "$ref": "#/definitions/id" },
+        "ids": { "$ref": "#/definitions/ids" }
+      },
+      "required" : [ "name", "method" ],
+      "allOf": [
+        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+      ],
+      "additionalProperties": false
+    },
+
+    "coordinate_system": {
+      "type": "object",
+      "properties": {
+        "$schema" : { "type": "string" },
+        "type": { "type": "string", "enum": ["CoordinateSystem"] },
+        "name": { "type": "string" },
+        "subtype": { "type": "string",
+                     "enum": ["Cartesian",
+                              "spherical",
+                              "ellipsoidal",
+                              "vertical",
+                              "ordinal",
+                              "parametric",
+                              "TemporalDateTime",
+                              "TemporalCount",
+                              "TemporalMeasure"]  },
+        "axis": {
+            "type": "array",
+            "items": { "$ref": "#/definitions/axis" }
+        },
+        "id": { "$ref": "#/definitions/id" },
+        "ids": { "$ref": "#/definitions/ids" }
+      },
+      "required" : [ "subtype", "axis" ],
+      "allOf": [
+        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+      ],
+      "additionalProperties": false
+    },
+
+    "crs": {
+      "oneOf": [
+        { "$ref": "#/definitions/bound_crs" },
+        { "$ref": "#/definitions/compound_crs" },
+        { "$ref": "#/definitions/derived_engineering_crs" },
+        { "$ref": "#/definitions/derived_geodetic_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" },
+        { "$ref": "#/definitions/parametric_crs" },
+        { "$ref": "#/definitions/projected_crs" },
+        { "$ref": "#/definitions/temporal_crs" },
+        { "$ref": "#/definitions/vertical_crs" }
+      ]
+    },
+
+    "datum": {
+      "oneOf": [
+        { "$ref": "#/definitions/geodetic_reference_frame" },
+        { "$ref": "#/definitions/vertical_reference_frame" },
+        { "$ref": "#/definitions/dynamic_geodetic_reference_frame" },
+        { "$ref": "#/definitions/dynamic_vertical_reference_frame" },
+        { "$ref": "#/definitions/temporal_datum" },
+        { "$ref": "#/definitions/parametric_datum" },
+        { "$ref": "#/definitions/engineering_datum" }
+      ]
+    },
+
+    "datum_ensemble": {
+      "type": "object",
+      "properties": {
+        "$schema" : { "type": "string" },
+        "type": { "type": "string", "enum": ["DatumEnsemble"] },
+        "name": { "type": "string" },
+        "members": {
+            "type": "array",
+            "items": {
+                "type": "object",
+                "properties": {
+                    "name": { "type": "string" },
+                    "id": { "$ref": "#/definitions/id" },
+                    "ids": { "$ref": "#/definitions/ids" }
+                },
+                "required" : [ "name" ],
+                "allOf": [
+                    { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+                ],
+                "additionalProperties": false
+            }
+        },
+        "ellipsoid": { "$ref": "#/definitions/ellipsoid" },
+        "accuracy": { "type": "string" },
+        "id": { "$ref": "#/definitions/id" },
+        "ids": { "$ref": "#/definitions/ids" }
+      },
+      "required" : [ "name", "members", "accuracy" ],
+      "allOf": [
+        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+      ],
+      "additionalProperties": false
+    },
+
+    "derived_engineering_crs": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string",
+                  "enum": ["DerivedEngineeringCRS"] },
+        "name": { "type": "string" },
+        "base_crs": { "$ref": "#/definitions/engineering_crs" },
+        "conversion": { "$ref": "#/definitions/conversion" },
+        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+     },
+     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
+     "additionalProperties": false
+    },
+
+    "derived_geodetic_crs": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string",
+                  "enum": ["DerivedGeodeticCRS",
+                           "DerivedGeographicCRS"] },
+        "name": { "type": "string" },
+        "base_crs": { "$ref": "#/definitions/geodetic_crs" },
+        "conversion": { "$ref": "#/definitions/conversion" },
+        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+     },
+     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
+     "additionalProperties": false
+    },
+
+    "derived_parametric_crs": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string",
+                  "enum": ["DerivedParametricCRS"] },
+        "name": { "type": "string" },
+        "base_crs": { "$ref": "#/definitions/parametric_crs" },
+        "conversion": { "$ref": "#/definitions/conversion" },
+        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+     },
+     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
+     "additionalProperties": false
+    },
+
+    "derived_projected_crs": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string",
+                  "enum": ["DerivedProjectedCRS"] },
+        "name": { "type": "string" },
+        "base_crs": { "$ref": "#/definitions/projected_crs" },
+        "conversion": { "$ref": "#/definitions/conversion" },
+        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+     },
+     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
+     "additionalProperties": false
+    },
+
+    "derived_temporal_crs": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string",
+                  "enum": ["DerivedTemporalCRS"] },
+        "name": { "type": "string" },
+        "base_crs": { "$ref": "#/definitions/temporal_crs" },
+        "conversion": { "$ref": "#/definitions/conversion" },
+        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+     },
+     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
+     "additionalProperties": false
+    },
+
+    "derived_vertical_crs": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string",
+                  "enum": ["DerivedVerticalCRS"] },
+        "name": { "type": "string" },
+        "base_crs": { "$ref": "#/definitions/vertical_crs" },
+        "conversion": { "$ref": "#/definitions/conversion" },
+        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+     },
+     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
+     "additionalProperties": false
+    },
+
+    "dynamic_geodetic_reference_frame": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/geodetic_reference_frame" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["DynamicGeodeticReferenceFrame"] },
+        "name": {},
+        "anchor": {},
+        "ellipsoid": {},
+        "prime_meridian": {},
+        "frame_reference_epoch": { "type": "number" },
+        "deformation_model": { "type": "string" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name", "ellipsoid", "frame_reference_epoch" ],
+      "additionalProperties": false
+    },
+
+    "dynamic_vertical_reference_frame": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/vertical_reference_frame" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["DynamicVerticalReferenceFrame"] },
+        "name": {},
+        "anchor": {},
+        "frame_reference_epoch": { "type": "number" },
+        "deformation_model": { "type": "string" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name", "frame_reference_epoch" ],
+      "additionalProperties": false
+    },
+
+    "ellipsoid": {
+      "type": "object",
+      "oneOf":[
+        {
+          "properties": {
+            "$schema" : { "type": "string" },
+            "type": { "type": "string", "enum": ["Ellipsoid"] },
+            "name": { "type": "string" },
+            "semi_major_axis": { "$ref": "#/definitions/value_in_metre_or_value_and_unit" },
+            "semi_minor_axis": { "$ref": "#/definitions/value_in_metre_or_value_and_unit" },
+            "id": { "$ref": "#/definitions/id" },
+            "ids": { "$ref": "#/definitions/ids" }
+          },
+          "required" : [ "name", "semi_major_axis", "semi_minor_axis" ],
+          "additionalProperties": false
+        },
+        {
+          "properties": {
+            "$schema" : { "type": "string" },
+            "type": { "type": "string", "enum": ["Ellipsoid"] },
+            "name": { "type": "string" },
+            "semi_major_axis": { "$ref": "#/definitions/value_in_metre_or_value_and_unit" },
+            "inverse_flattening": { "type": "number" },
+            "id": { "$ref": "#/definitions/id" },
+           "ids": { "$ref": "#/definitions/ids" }
+          },
+          "required" : [ "name", "semi_major_axis", "inverse_flattening" ],
+          "additionalProperties": false
+        },
+        {
+          "properties": {
+            "$schema" : { "type": "string" },
+            "type": { "type": "string", "enum": ["Ellipsoid"] },
+            "name": { "type": "string" },
+            "radius": { "$ref": "#/definitions/value_in_metre_or_value_and_unit" },
+            "id": { "$ref": "#/definitions/id" },
+            "ids": { "$ref": "#/definitions/ids" }
+          },
+          "required" : [ "name", "radius" ],
+         "additionalProperties": false
+        }
+      ],
+      "allOf": [
+        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+      ]
+    },
+
+    "engineering_crs": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["EngineeringCRS"] },
+        "name": { "type": "string" },
+        "datum": { "$ref": "#/definitions/engineering_datum" },
+        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name", "datum" ],
+      "additionalProperties": false
+    },
+
+    "engineering_datum": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["EngineeringDatum"] },
+        "name": { "type": "string" },
+        "anchor": { "type": "string" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name" ],
+      "additionalProperties": false
+    },
+
+    "geodetic_crs": {
+      "type": "object",
+      "properties": {
+        "type": { "type": "string", "enum": ["GeodeticCRS", "GeographicCRS"] },
+        "name": { "type": "string" },
+        "datum": {
+            "oneOf": [
+                { "$ref": "#/definitions/geodetic_reference_frame" },
+                { "$ref": "#/definitions/dynamic_geodetic_reference_frame" }
+            ]
+        },
+        "datum_ensemble": { "$ref": "#/definitions/datum_ensemble" },
+        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name" ],
+      "description": "One and only one of datum and datum_ensemble must be provided",
+      "allOf": [
+        { "$ref": "#/definitions/object_usage" },
+        { "$ref": "#/definitions/one_and_only_one_of_datum_or_datum_ensemble" }
+      ],
+      "additionalProperties": false
+    },
+
+    "geodetic_reference_frame": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["GeodeticReferenceFrame"] },
+        "name": { "type": "string" },
+        "anchor": { "type": "string" },
+        "ellipsoid": { "$ref": "#/definitions/ellipsoid" },
+        "prime_meridian": { "$ref": "#/definitions/prime_meridian" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name", "ellipsoid" ],
+      "additionalProperties": false
+    },
+
+    "id": {
+      "type": "object",
+      "properties": {
+        "authority": { "type": "string" },
+        "code": {
+          "oneOf": [ { "type": "string" }, { "type": "integer" } ]
+        }
+      },
+      "required" : [ "authority", "code" ],
+      "additionalProperties": false
+    },
+
+    "ids": {
+      "type": "array",
+      "items": { "$ref": "#/definitions/id" }
+    },
+
+    "method": {
+      "type": "object",
+      "properties": {
+        "$schema" : { "type": "string" },
+        "type": { "type": "string", "enum": ["OperationMethod"]},
+        "name": { "type": "string" },
+        "id": { "$ref": "#/definitions/id" },
+        "ids": { "$ref": "#/definitions/ids" }
+      },
+      "required" : [ "name" ],
+      "allOf": [
+        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+      ],
+      "additionalProperties": false
+    },
+
+    "id_ids_mutually_exclusive": {
+        "not": {
+            "type": "object",
+            "required": [ "id", "ids" ]
+        }
+    },
+
+    "one_and_only_one_of_datum_or_datum_ensemble": {
+      "allOf": [
+        {
+            "not": {
+                "type": "object",
+                "required": [ "datum", "datum_ensemble" ]
+            }
+        },
+        {
+            "oneOf": [
+                { "type": "object", "required": ["datum"] },
+                { "type": "object", "required": ["datum_ensemble"] }
+            ]
+        }
+      ]
+    },
+
+    "object_usage": {
+      "anyOf": [
+      {
+        "type": "object",
+        "properties": {
+            "$schema" : { "type": "string" },
+            "scope": { "type": "string" },
+            "area": { "type": "string" },
+            "bbox": { "$ref": "#/definitions/bbox" },
+            "remarks": { "type": "string" },
+            "id": { "$ref": "#/definitions/id" },
+            "ids": { "$ref": "#/definitions/ids" }
+        },
+        "allOf": [
+            { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+        ]
+      },
+      {
+        "type": "object",
+        "properties": {
+            "$schema" : { "type": "string" },
+            "usages": { "$ref": "#/definitions/usages" },
+            "remarks": { "type": "string" },
+            "id": { "$ref": "#/definitions/id" },
+            "ids": { "$ref": "#/definitions/ids" }
+        },
+        "allOf": [
+            { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+        ]
+      }
+      ]
+    },
+
+    "parameter_value": {
+      "type": "object",
+      "properties": {
+        "$schema" : { "type": "string" },
+        "type": { "type": "string", "enum": ["ParameterValue"] },
+        "name": { "type": "string" },
+        "value": {
+          "oneOf": [
+            { "type": "string" },
+            { "type": "number" }
+           ]
+        },
+        "unit": { "$ref": "#/definitions/unit" },
+        "id": { "$ref": "#/definitions/id" },
+        "ids": { "$ref": "#/definitions/ids" }
+      },
+      "required" : [ "name", "value" ],
+      "allOf": [
+        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+      ],
+      "additionalProperties": false
+    },
+
+    "parametric_crs": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["ParametricCRS"] },
+        "name": { "type": "string" },
+        "datum": { "$ref": "#/definitions/parametric_datum" },
+        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name", "datum" ],
+      "additionalProperties": false
+    },
+
+    "parametric_datum": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["ParametricDatum"] },
+        "name": { "type": "string" },
+        "anchor": { "type": "string" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name" ],
+      "additionalProperties": false
+    },
+
+    "prime_meridian": {
+      "type": "object",
+      "properties": {
+        "$schema" : { "type": "string" },
+        "type": { "type": "string", "enum": ["PrimeMeridian"] },
+        "name": { "type": "string" },
+        "longitude": { "$ref": "#/definitions/value_and_unit" },
+        "id": { "$ref": "#/definitions/id" },
+        "ids": { "$ref": "#/definitions/ids" }
+      },
+      "required" : [ "name" ],
+      "allOf": [
+        { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+      ],
+      "additionalProperties": false
+    },
+
+    "single_operation": {
+      "oneOf": [
+        { "$ref": "#/definitions/conversion" },
+        { "$ref": "#/definitions/transformation" }
+      ]
+    },
+
+    "projected_crs": {
+      "type": "object",
+      "allOf": [{ "$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": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+     },
+     "required" : [ "name", "base_crs", "conversion", "coordinate_system" ],
+     "additionalProperties": false
+    },
+
+    "temporal_crs": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["TemporalCRS"] },
+        "name": { "type": "string" },
+        "datum": { "$ref": "#/definitions/temporal_datum" },
+        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name", "datum" ],
+      "additionalProperties": false
+    },
+
+    "temporal_datum": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["TemporalDatum"] },
+        "name": { "type": "string" },
+        "calendar": { "type": "string" },
+        "time_origin": { "type": "string" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name", "calendar" ],
+      "additionalProperties": false
+    },
+
+    "transformation": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["Transformation"] },
+        "name": { "type": "string" },
+        "source_crs": { "$ref": "#/definitions/crs" },
+        "target_crs": { "$ref": "#/definitions/crs" },
+        "interpolation_crs": { "$ref": "#/definitions/crs" },
+        "method": { "$ref": "#/definitions/method" },
+        "parameters": {
+            "type": "array",
+            "items": { "$ref": "#/definitions/parameter_value" }
+        },
+        "accuracy": { "type": "string" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name", "source_crs", "target_crs", "method", "parameters" ],
+      "additionalProperties": false
+    },
+
+    "unit": {
+      "oneOf": [
+      {
+        "type": "string",
+        "enum": ["metre", "degree", "unity"]
+      },
+      {
+        "type": "object",
+        "properties": {
+          "type": { "type": "string",
+                    "enum": ["LinearUnit", "AngularUnit", "ScaleUnit",
+                             "TimeUnit", "ParametricUnit", "Unit"] },
+          "name": { "type": "string" },
+          "conversion_factor": { "type": "number" },
+          "id": { "$ref": "#/definitions/id" },
+          "ids": { "$ref": "#/definitions/ids" }
+         },
+         "required" : [ "type", "name" ],
+         "allOf": [
+            { "$ref": "#/definitions/id_ids_mutually_exclusive" }
+          ],
+         "additionalProperties": false
+      }
+      ]
+    },
+
+    "usages": {
+        "type": "array",
+        "items": {
+          "type": "object",
+          "properties": {
+            "scope": { "type": "string" },
+            "area": { "type": "string" },
+            "bbox": { "$ref": "#/definitions/bbox" }
+           },
+          "additionalProperties": false
+        }
+    },
+
+    "value_and_unit": {
+      "type": "object",
+      "properties": {
+        "value": { "type": "number" },
+        "unit": { "$ref": "#/definitions/unit" }
+      },
+      "required" : [ "value", "unit" ],
+      "additionalProperties": false
+    },
+
+    "value_in_metre_or_value_and_unit": {
+      "oneOf": [
+        { "type": "number" },
+        { "$ref": "#/definitions/value_and_unit" }
+      ]
+    },
+
+    "vertical_crs": {
+      "type": "object",
+      "properties": {
+        "type": { "type": "string", "enum": ["VerticalCRS"] },
+        "name": { "type": "string" },
+        "datum": {
+            "oneOf": [
+                { "$ref": "#/definitions/vertical_reference_frame" },
+                { "$ref": "#/definitions/dynamic_vertical_reference_frame" }
+            ]
+        },
+        "datum_ensemble": { "$ref": "#/definitions/datum_ensemble" },
+        "coordinate_system": { "$ref": "#/definitions/coordinate_system" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name"],
+      "description": "One and only one of datum and datum_ensemble must be provided",
+      "allOf": [
+        { "$ref": "#/definitions/object_usage" },
+        { "$ref": "#/definitions/one_and_only_one_of_datum_or_datum_ensemble" }
+      ],
+      "additionalProperties": false
+    },
+
+    "vertical_reference_frame": {
+      "type": "object",
+      "allOf": [{ "$ref": "#/definitions/object_usage" }],
+      "properties": {
+        "type": { "type": "string", "enum": ["VerticalReferenceFrame"] },
+        "name": { "type": "string" },
+        "anchor": { "type": "string" },
+        "$schema" : {},
+        "scope": {},
+        "area": {},
+        "bbox": {},
+        "usages": {},
+        "remarks": {},
+        "id": {}, "ids": {}
+      },
+      "required" : [ "name" ],
+      "additionalProperties": false
+    }
+
+  }
+}
-- 
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