EPSG:10997

COMPD_CS["ETRS89-GBR [OSNet v2009] + London Survey Grid height",
    GEOGCS["ETRS89-GBR [OSNet v2009]",
        DATUM["OSNet_v2009",
            SPHEROID["GRS 1980",6378137,298.257222101,
                AUTHORITY["EPSG","7019"]],
            AUTHORITY["EPSG","1425"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","11009"]],
    VERT_CS["London Survey Grid height",
        VERT_DATUM["London Survey Grid height datum",2005,
            AUTHORITY["EPSG","1423"]],
        UNIT["metre",1,
            AUTHORITY["EPSG","9001"]],
        AXIS["Gravity-related height",UP],
        AUTHORITY["EPSG","10989"]],
    AUTHORITY["EPSG","10997"]]

COMPOUNDCRS["ETRS89-GBR [OSNet v2009] + London Survey Grid height",
    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]]],
    VERTCRS["London Survey Grid height",
        VDATUM["London Survey Grid height datum"],
        CS[vertical,1],
            AXIS["gravity-related height (H)",up,
                LENGTHUNIT["metre",1]]],
    USAGE[
        SCOPE["Reversible geoid model transformation."],
        AREA["United Kingdom (UK) - Greater London and surrounding area."],
        BBOX[51.1,-1.33,52,0.8]],
    ID["EPSG",10997]]

GEOGCS["GCS_ETRS89-GBR_OSNet_v2009",
    DATUM["D_ETRS_1989",
        SPHEROID["GRS_1980",6378137.0,298.257222101]],
    PRIMEM["Greenwich",0.0],
    UNIT["Degree",0.0174532925199433]],
VERTCS["London_Survey_Grid_height",
    VDATUM["London_Survey_Grid_height_datum"],
    PARAMETER["Vertical_Shift",0.0],
    PARAMETER["Direction",1.0],
    UNIT["Meter",1.0]]

proj4.defs("EPSG:10997","+proj=longlat +ellps=GRS80 +vunits=m +no_defs +type=crs");

{
    "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
    "type": "CompoundCRS",
    "name": "ETRS89-GBR [OSNet v2009] + London Survey Grid height",
    "components": [
        {
            "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"
                    }
                ]
            },
            "remarks": "Horizontal component of second national realization of ETRS89 in Great Britain. Replaces ETRS89-GBR [OSNet v2001] from 2016."
        },
        {
            "type": "VerticalCRS",
            "name": "London Survey Grid height",
            "datum": {
                "type": "VerticalReferenceFrame",
                "name": "London Survey Grid height datum"
            },
            "coordinate_system": {
                "subtype": "vertical",
                "axis": [
                    {
                        "name": "Gravity-related height",
                        "abbreviation": "H",
                        "direction": "up",
                        "unit": "metre"
                    }
                ]
            }
        }
    ],
    "scope": "Reversible geoid model transformation.",
    "area": "United Kingdom (UK) - Greater London and surrounding area.",
    "bbox": {
        "south_latitude": 51.1,
        "west_longitude": -1.33,
        "north_latitude": 52,
        "east_longitude": 0.8
    },
    "id": {
        "authority": "EPSG",
        "code": 10997
    }
}

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=longlat +ellps=GRS80 +vunits=m +no_defs +type=crs">
	<Layer srs="+proj=longlat +ellps=GRS80 +vunits=m +no_defs +type=crs">
	</Layer>
</Map>

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 10997, 'EPSG', 10997, '+proj=longlat +ellps=GRS80 +vunits=m +no_defs +type=crs', 'COMPD_CS["ETRS89-GBR [OSNet v2009] + London Survey Grid height",GEOGCS["ETRS89-GBR [OSNet v2009]",DATUM["OSNet_v2009",SPHEROID["GRS 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","1425"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","11009"]],VERT_CS["London Survey Grid height",VERT_DATUM["London Survey Grid height datum",2005,AUTHORITY["EPSG","1423"]],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Gravity-related height",UP],AUTHORITY["EPSG","10989"]],AUTHORITY["EPSG","10997"]]');