EPSG:9314

COORDINATEOPERATION["NZVD2016 height to Dunedin 1958 height (2)",
    VERSION["LINZ-NZ DUNE gtx"],
    SOURCECRS[
        VERTCRS["NZVD2016 height",
            VDATUM["New Zealand Vertical Datum 2016"],
            CS[vertical,1],
                AXIS["gravity-related height (H)",up,
                    LENGTHUNIT["metre",1]],
            ID["EPSG",7839]]],
    TARGETCRS[
        VERTCRS["Dunedin 1958 height",
            VDATUM["Dunedin 1958"],
            CS[vertical,1],
                AXIS["gravity-related height (H)",up,
                    LENGTHUNIT["metre",1]],
            ID["EPSG",5761]]],
    METHOD["Vertical Offset by Grid Interpolation (gtx)",
        ID["EPSG",1084]],
    PARAMETERFILE["Vertical offset file","duneht1958-nzvd2016.gtx"],
    INTERPOLATIONCRS[
        GEOGCRS["NZGD2000",
            DATUM["New Zealand Geodetic Datum 2000",
                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]]]],
    OPERATIONACCURACY[0.02],
    USAGE[
        SCOPE["Change of height to a different vertical reference surface."],
        AREA["New Zealand - South Island - between approximately 44°S and 46°S - Dunedin vertical CRS area."],
        BBOX[-46.4,167.73,-43.82,171.28]],
    ID["EPSG",9314],
    REMARK["Derived at 197 control points. Mean offset 0.326m, standard deviation 0.043m, maximum difference from mean 0.152m. Supersedes NZVD2016 height to Dunedin 1958 height (1) (code 7862) after change of grid file format."]]

proj4.defs("EPSG:9314","+proj=vgridshift +grids=nz_linz_duneht1958-nzvd2016.tif +multiplier=1");

{
    "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
    "type": "Transformation",
    "name": "NZVD2016 height to Dunedin 1958 height (2)",
    "source_crs": {
        "type": "VerticalCRS",
        "name": "NZVD2016 height",
        "datum": {
            "type": "VerticalReferenceFrame",
            "name": "New Zealand Vertical Datum 2016"
        },
        "coordinate_system": {
            "subtype": "vertical",
            "axis": [
                {
                    "name": "Gravity-related height",
                    "abbreviation": "H",
                    "direction": "up",
                    "unit": "metre"
                }
            ]
        },
        "id": {
            "authority": "EPSG",
            "code": 7839
        }
    },
    "target_crs": {
        "type": "VerticalCRS",
        "name": "Dunedin 1958 height",
        "datum": {
            "type": "VerticalReferenceFrame",
            "name": "Dunedin 1958"
        },
        "coordinate_system": {
            "subtype": "vertical",
            "axis": [
                {
                    "name": "Gravity-related height",
                    "abbreviation": "H",
                    "direction": "up",
                    "unit": "metre"
                }
            ]
        },
        "id": {
            "authority": "EPSG",
            "code": 5761
        }
    },
    "interpolation_crs": {
        "type": "GeographicCRS",
        "name": "NZGD2000",
        "datum": {
            "type": "GeodeticReferenceFrame",
            "name": "New Zealand Geodetic Datum 2000",
            "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": 4167
        }
    },
    "method": {
        "name": "Vertical Offset by Grid Interpolation (gtx)",
        "id": {
            "authority": "EPSG",
            "code": 1084
        }
    },
    "parameters": [
        {
            "name": "Vertical offset file",
            "value": "duneht1958-nzvd2016.gtx",
            "id": {
                "authority": "EPSG",
                "code": 8732
            }
        }
    ],
    "accuracy": "0.02",
    "scope": "Change of height to a different vertical reference surface.",
    "area": "New Zealand - South Island - between approximately 44°S and 46°S - Dunedin vertical CRS area.",
    "bbox": {
        "south_latitude": -46.4,
        "west_longitude": 167.73,
        "north_latitude": -43.82,
        "east_longitude": 171.28
    },
    "id": {
        "authority": "EPSG",
        "code": 9314
    },
    "remarks": "Derived at 197 control points. Mean offset 0.326m, standard deviation 0.043m, maximum difference from mean 0.152m. Supersedes NZVD2016 height to Dunedin 1958 height (1) (code 7862) after change of grid file format."
}

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=vgridshift +grids=nz_linz_duneht1958-nzvd2016.tif +multiplier=1">
	<Layer srs="+proj=vgridshift +grids=nz_linz_duneht1958-nzvd2016.tif +multiplier=1">
	</Layer>
</Map>

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 9314, 'EPSG', 9314, '+proj=vgridshift +grids=nz_linz_duneht1958-nzvd2016.tif +multiplier=1', 'None');