EPSG:9740

COORDINATEOPERATION["ETRS89-GBR [OSNet v2009] to EOS21-IRF (1)",
    VERSION["NR-Gbr EOS21 OSNet2009"],
    SOURCECRS[
        GEOGCRS["ETRS89-GBR [OSNet v2009]",
            DATUM["OSNet v2009",
                ELLIPSOID["GRS 1980",6378137,298.257222101,
                    LENGTHUNIT["metre",1]],
                ANCHOREPOCH[2009.756]],
            PRIMEM["Greenwich",0,
                ANGLEUNIT["degree",0.0174532925199433]],
            CS[ellipsoidal,2],
                AXIS["geodetic latitude (Lat)",north,
                    ORDER[1],
                    ANGLEUNIT["degree",0.0174532925199433]],
                AXIS["geodetic longitude (Lon)",east,
                    ORDER[2],
                    ANGLEUNIT["degree",0.0174532925199433]],
            ID["EPSG",11009]]],
    TARGETCRS[
        GEOGCRS["EOS21-IRF",
            DATUM["EOS21 Intermediate Reference Frame",
                ELLIPSOID["GRS 1980",6378137,298.257222101,
                    LENGTHUNIT["metre",1]]],
            PRIMEM["Greenwich",0,
                ANGLEUNIT["degree",0.0174532925199433]],
            CS[ellipsoidal,2],
                AXIS["geodetic latitude (Lat)",north,
                    ORDER[1],
                    ANGLEUNIT["degree",0.0174532925199433]],
                AXIS["geodetic longitude (Lon)",east,
                    ORDER[2],
                    ANGLEUNIT["degree",0.0174532925199433]],
            ID["EPSG",9739]]],
    METHOD["NTv2",
        ID["EPSG",9615]],
    PARAMETERFILE["Latitude and longitude difference file","TN15-ETRS89-to-EOS21-IRF.gsb"],
    OPERATIONACCURACY[0.0],
    USAGE[
        SCOPE["Engineering survey and topographic mapping for railway applications."],
        AREA["United Kingdom (UK) - on or related to the complex of rail routes in the East of Scotland, incorporating the route from Tweedbank through the Borders to Edinburgh; the line from Edinburgh to Aberdeen; routes via Kirkaldy and Cowdenbeath; and routes via Leuchars and Perth to Dundee. "],
        BBOX[55.55,-3.56,57.21,-1.94]],
    ID["EPSG",9740],
    REMARK["In conjunction with the EOS21-TM map projection (code 9738) applied to EOS21-IRF (code 9739), emulates the EOS21 Snake projection. Applied to ETRS89 (as realized through the OSNet v2009 CORS) defines EOS21-IRF hence is errorless."]]

proj4.defs("EPSG:9740","+proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=hgridshift +grids=TN15-ETRS89-to-EOS21-IRF.gsb +step +proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap +order=2,1");

{
    "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
    "type": "Transformation",
    "name": "ETRS89-GBR [OSNet v2009] to EOS21-IRF (1)",
    "source_crs": {
        "type": "GeographicCRS",
        "name": "ETRS89-GBR [OSNet v2009]",
        "datum": {
            "type": "GeodeticReferenceFrame",
            "name": "OSNet v2009",
            "anchor_epoch": 2009.756,
            "ellipsoid": {
                "name": "GRS 1980",
                "semi_major_axis": 6378137,
                "inverse_flattening": 298.257222101
            }
        },
        "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": 11009
        },
        "remarks": "Horizontal component of second national realization of ETRS89 in Great Britain. Replaces ETRS89-GBR [OSNet v2001] from 2016."
    },
    "target_crs": {
        "type": "GeographicCRS",
        "name": "EOS21-IRF",
        "datum": {
            "type": "GeodeticReferenceFrame",
            "name": "EOS21 Intermediate Reference Frame",
            "ellipsoid": {
                "name": "GRS 1980",
                "semi_major_axis": 6378137,
                "inverse_flattening": 298.257222101
            }
        },
        "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": 9739
        },
        "remarks": "Intermediate CRS created in 2021 to assist the emulation of the ETRS89 / EOS21 SnakeGrid projected CRS through transformation ETRS89-GBR [OSNet v2009] to EOS21-IRF (1) (code 9740) used in conjunction with the EOS21-TM map projection (code 9738)."
    },
    "method": {
        "name": "NTv2",
        "id": {
            "authority": "EPSG",
            "code": 9615
        }
    },
    "parameters": [
        {
            "name": "Latitude and longitude difference file",
            "value": "TN15-ETRS89-to-EOS21-IRF.gsb",
            "id": {
                "authority": "EPSG",
                "code": 8656
            }
        }
    ],
    "accuracy": "0.0",
    "scope": "Engineering survey and topographic mapping for railway applications.",
    "area": "United Kingdom (UK) - on or related to the complex of rail routes in the East of Scotland, incorporating the route from Tweedbank through the Borders to Edinburgh; the line from Edinburgh to Aberdeen; routes via Kirkaldy and Cowdenbeath; and routes via Leuchars and Perth to Dundee. ",
    "bbox": {
        "south_latitude": 55.55,
        "west_longitude": -3.56,
        "north_latitude": 57.21,
        "east_longitude": -1.94
    },
    "id": {
        "authority": "EPSG",
        "code": 9740
    },
    "remarks": "In conjunction with the EOS21-TM map projection (code 9738) applied to EOS21-IRF (code 9739), emulates the EOS21 Snake projection. Applied to ETRS89 (as realized through the OSNet v2009 CORS) defines EOS21-IRF hence is errorless."
}

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=hgridshift +grids=TN15-ETRS89-to-EOS21-IRF.gsb +step +proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap +order=2,1">
	<Layer srs="+proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=hgridshift +grids=TN15-ETRS89-to-EOS21-IRF.gsb +step +proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap +order=2,1">
	</Layer>
</Map>

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 9740, 'EPSG', 9740, '+proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=hgridshift +grids=TN15-ETRS89-to-EOS21-IRF.gsb +step +proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap +order=2,1', 'None');