EPSG:9275

COORDINATEOPERATION["GHA height to EVRF2000 Austria height (1)",
    VERSION["BEV-Aut"],
    SOURCECRS[
        VERTCRS["GHA height",
            VDATUM["Gebrauchshohen ADRIA"],
            CS[vertical,1],
                AXIS["gravity-related height (H)",up,
                    LENGTHUNIT["metre",1]],
            ID["EPSG",5778]]],
    TARGETCRS[
        VERTCRS["EVRF2000 Austria height",
            VDATUM["European Vertical Reference Frame 2000 Austria"],
            CS[vertical,1],
                AXIS["gravity-related height (H)",up,
                    LENGTHUNIT["metre",1]],
            ID["EPSG",9274]]],
    METHOD["Vertical Offset by Grid Interpolation (BEV AT)",
        ID["EPSG",1080]],
    PARAMETERFILE["Vertical offset file","GV_HoehenGrid_V1.csv"],
    INTERPOLATIONCRS[
        GEOGCRS["MGI",
            DATUM["Militar-Geographische Institut",
                ELLIPSOID["Bessel 1841",6377397.155,299.1528128,
                    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]]]],
    OPERATIONACCURACY[0.05],
    USAGE[
        SCOPE["Change of height to a different vertical reference surface."],
        AREA["Austria."],
        BBOX[46.4,9.53,49.02,17.17]],
    ID["EPSG",9275],
    REMARK["Care! Austrian literature describes this transformation in direction EVRF2000 Austria height to GHA height with offset subtracted. EPSG method has offset as an addition. See method formula and example. The grid is implemented in BEV-Transformator."]]

proj4.defs("EPSG:9275","+proj=vgridshift +grids=at_bev_GV_Hoehengrid_V1.tif +multiplier=1");

{
    "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
    "type": "Transformation",
    "name": "GHA height to EVRF2000 Austria height (1)",
    "source_crs": {
        "type": "VerticalCRS",
        "name": "GHA height",
        "datum": {
            "type": "VerticalReferenceFrame",
            "name": "Gebrauchshohen ADRIA"
        },
        "coordinate_system": {
            "subtype": "vertical",
            "axis": [
                {
                    "name": "Gravity-related height",
                    "abbreviation": "H",
                    "direction": "up",
                    "unit": "metre"
                }
            ]
        },
        "id": {
            "authority": "EPSG",
            "code": 5778
        }
    },
    "target_crs": {
        "type": "VerticalCRS",
        "name": "EVRF2000 Austria height",
        "datum": {
            "type": "VerticalReferenceFrame",
            "name": "European Vertical Reference Frame 2000 Austria"
        },
        "coordinate_system": {
            "subtype": "vertical",
            "axis": [
                {
                    "name": "Gravity-related height",
                    "abbreviation": "H",
                    "direction": "up",
                    "unit": "metre"
                }
            ]
        },
        "id": {
            "authority": "EPSG",
            "code": 9274
        }
    },
    "interpolation_crs": {
        "type": "GeographicCRS",
        "name": "MGI",
        "datum": {
            "type": "GeodeticReferenceFrame",
            "name": "Militar-Geographische Institut",
            "ellipsoid": {
                "name": "Bessel 1841",
                "semi_major_axis": 6377397.155,
                "inverse_flattening": 299.1528128
            }
        },
        "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": 4312
        }
    },
    "method": {
        "name": "Vertical Offset by Grid Interpolation (BEV AT)",
        "id": {
            "authority": "EPSG",
            "code": 1080
        }
    },
    "parameters": [
        {
            "name": "Vertical offset file",
            "value": "GV_HoehenGrid_V1.csv",
            "id": {
                "authority": "EPSG",
                "code": 8732
            }
        }
    ],
    "accuracy": "0.05",
    "scope": "Change of height to a different vertical reference surface.",
    "area": "Austria.",
    "bbox": {
        "south_latitude": 46.4,
        "west_longitude": 9.53,
        "north_latitude": 49.02,
        "east_longitude": 17.17
    },
    "id": {
        "authority": "EPSG",
        "code": 9275
    },
    "remarks": "Care! Austrian literature describes this transformation in direction EVRF2000 Austria height to GHA height with offset subtracted. EPSG method has offset as an addition. See method formula and example. The grid is implemented in BEV-Transformator."
}

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=vgridshift +grids=at_bev_GV_Hoehengrid_V1.tif +multiplier=1">
	<Layer srs="+proj=vgridshift +grids=at_bev_GV_Hoehengrid_V1.tif +multiplier=1">
	</Layer>
</Map>

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 9275, 'EPSG', 9275, '+proj=vgridshift +grids=at_bev_GV_Hoehengrid_V1.tif +multiplier=1', 'None');