EPSG:9920 - OSGB36 / British National Grid + BI height

{
  "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
  "type": "CompoundCRS",
  "name": "OSGB36 / British National Grid + BI height",
  "components": [
    {
      "type": "ProjectedCRS",
      "name": "OSGB36 / British National Grid",
      "base_crs": {
        "name": "OSGB36",
        "datum": {
          "type": "GeodeticReferenceFrame",
          "name": "Ordnance Survey of Great Britain 1936",
          "ellipsoid": {
            "name": "Airy 1830",
            "semi_major_axis": 6377563.396,
            "inverse_flattening": 299.3249646
          }
        },
        "coordinate_system": {
          "subtype": "ellipsoidal",
          "axis": [
            {
              "name": "Geodetic latitude",
              "abbreviation": "Lat",
              "direction": "north",
              "unit": "degree"
            },
            {
              "name": "Geodetic longitude",
              "abbreviation": "Lon",
              "direction": "east",
              "unit": "degree"
            }
          ]
        },
        "id": {
          "authority": "EPSG",
          "code": 4277
        }
      },
      "conversion": {
        "name": "British National Grid",
        "method": {
          "name": "Transverse Mercator",
          "id": {
            "authority": "EPSG",
            "code": 9807
          }
        },
        "parameters": [
          {
            "name": "Latitude of natural origin",
            "value": 49,
            "unit": "degree",
            "id": {
              "authority": "EPSG",
              "code": 8801
            }
          },
          {
            "name": "Longitude of natural origin",
            "value": -2,
            "unit": "degree",
            "id": {
              "authority": "EPSG",
              "code": 8802
            }
          },
          {
            "name": "Scale factor at natural origin",
            "value": 0.9996012717,
            "unit": "unity",
            "id": {
              "authority": "EPSG",
              "code": 8805
            }
          },
          {
            "name": "False easting",
            "value": 400000,
            "unit": "metre",
            "id": {
              "authority": "EPSG",
              "code": 8806
            }
          },
          {
            "name": "False northing",
            "value": -100000,
            "unit": "metre",
            "id": {
              "authority": "EPSG",
              "code": 8807
            }
          }
        ]
      },
      "coordinate_system": {
        "subtype": "Cartesian",
        "axis": [
          {
            "name": "Easting",
            "abbreviation": "E",
            "direction": "east",
            "unit": "metre"
          },
          {
            "name": "Northing",
            "abbreviation": "N",
            "direction": "north",
            "unit": "metre"
          }
        ]
      }
    },
    {
      "type": "VerticalCRS",
      "name": "BI height",
      "datum_ensemble": {
        "name": "British Isles height ensemble",
        "members": [
          {
            "name": "Malin Head",
            "id": {
              "authority": "EPSG",
              "code": 5130
            }
          },
          {
            "name": "Belfast Lough",
            "id": {
              "authority": "EPSG",
              "code": 5131
            }
          },
          {
            "name": "Ordnance Datum Newlyn",
            "id": {
              "authority": "EPSG",
              "code": 5101
            }
          },
          {
            "name": "Ordnance Datum Newlyn (Offshore)",
            "id": {
              "authority": "EPSG",
              "code": 1164
            }
          },
          {
            "name": "Ordnance Datum Newlyn (Orkney Isles)",
            "id": {
              "authority": "EPSG",
              "code": 5138
            }
          },
          {
            "name": "Lerwick",
            "id": {
              "authority": "EPSG",
              "code": 5140
            }
          },
          {
            "name": "Stornoway",
            "id": {
              "authority": "EPSG",
              "code": 5144
            }
          },
          {
            "name": "Douglas",
            "id": {
              "authority": "EPSG",
              "code": 5148
            }
          },
          {
            "name": "St. Marys",
            "id": {
              "authority": "EPSG",
              "code": 5147
            }
          }
        ],
        "accuracy": "0.4",
        "id": {
          "authority": "EPSG",
          "code": 1288
        }
      },
      "coordinate_system": {
        "subtype": "vertical",
        "axis": [
          {
            "name": "Gravity-related height",
            "abbreviation": "H",
            "direction": "up",
            "unit": "metre"
          }
        ]
      }
    }
  ],
  "scope": "Spatial referencing.",
  "area": "United Kingdom (UK) - offshore to boundary of UKCS within 49°45'N to 61°N and 9°W to 2°E; onshore Great Britain (England, Wales and Scotland). Isle of Man onshore.",
  "bbox": {
    "south_latitude": 49.75,
    "west_longitude": -9.01,
    "north_latitude": 61.01,
    "east_longitude": 2.01
  },
  "id": {
    "authority": "EPSG",
    "code": 9920
  }
}

{'crs_wkt': 'COMPOUNDCRS["OSGB36 / British National Grid + BI '
            'height",PROJCRS["OSGB36 / British National '
            'Grid",BASEGEOGCRS["OSGB36",DATUM["Ordnance Survey of Great '
            'Britain 1936",ELLIPSOID["Airy '
            '1830",6377563.396,299.3249646,LENGTHUNIT["metre",1]]],PRIMEM["Greenwich",0,ANGLEUNIT["degree",0.0174532925199433]],ID["EPSG",4277]],CONVERSION["British '
            'National Grid",METHOD["Transverse '
            'Mercator",ID["EPSG",9807]],PARAMETER["Latitude of natural '
            'origin",49,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8801]],PARAMETER["Longitude '
            'of natural '
            'origin",-2,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8802]],PARAMETER["Scale '
            'factor at natural '
            'origin",0.9996012717,SCALEUNIT["unity",1],ID["EPSG",8805]],PARAMETER["False '
            'easting",400000,LENGTHUNIT["metre",1],ID["EPSG",8806]],PARAMETER["False '
            'northing",-100000,LENGTHUNIT["metre",1],ID["EPSG",8807]]],CS[Cartesian,2],AXIS["(E)",east,ORDER[1],LENGTHUNIT["metre",1]],AXIS["(N)",north,ORDER[2],LENGTHUNIT["metre",1]]],VERTCRS["BI '
            'height",ENSEMBLE["British Isles height ensemble",MEMBER["Malin '
            'Head"],MEMBER["Belfast Lough"],MEMBER["Ordnance Datum '
            'Newlyn"],MEMBER["Ordnance Datum Newlyn '
            '(Offshore)"],MEMBER["Ordnance Datum Newlyn (Orkney '
            'Isles)"],MEMBER["Lerwick"],MEMBER["Stornoway"],MEMBER["Douglas"],MEMBER["St. '
            'Marys"],ENSEMBLEACCURACY[0.4]],CS[vertical,1],AXIS["gravity-related '
            'height (H)",up,LENGTHUNIT["metre",1]]],USAGE[SCOPE["Spatial '
            'referencing."],AREA["United Kingdom (UK) - offshore to boundary '
            "of UKCS within 49°45'N to 61°N and 9°W to 2°E; onshore Great "
            'Britain (England, Wales and Scotland). Isle of Man '
            'onshore."],BBOX[49.75,-9.01,61.01,2.01]],ID["EPSG",9920]]',
 'false_easting': 400000.0,
 'false_northing': -100000.0,
 'geographic_crs_name': 'OSGB36',
 'grid_mapping_name': 'transverse_mercator',
 'horizontal_datum_name': 'Ordnance Survey of Great Britain 1936',
 'inverse_flattening': 299.3249646,
 'latitude_of_projection_origin': 49.0,
 'longitude_of_central_meridian': -2.0,
 'longitude_of_prime_meridian': 0.0,
 'prime_meridian_name': 'Greenwich',
 'projected_crs_name': 'OSGB36 / British National Grid',
 'reference_ellipsoid_name': 'Airy 1830',
 'scale_factor_at_central_meridian': 0.9996012717,
 'semi_major_axis': 6377563.396,
 'semi_minor_axis': 6356256.909237285}