EPSG:7406

COMPD_CS["NAD27 + NGVD29 height (ftUS)",
    GEOGCS["NAD27",
        DATUM["North_American_Datum_1927",
            SPHEROID["Clarke 1866",6378206.4,294.978698213898,
                AUTHORITY["EPSG","7008"]],
            AUTHORITY["EPSG","6267"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","4267"]],
    VERT_CS["NGVD29 height (ftUS)",
        VERT_DATUM["National Geodetic Vertical Datum 1929",2005,
            AUTHORITY["EPSG","5102"]],
        UNIT["US survey foot",0.304800609601219,
            AUTHORITY["EPSG","9003"]],
        AXIS["Gravity-related height",UP],
        AUTHORITY["EPSG","5702"]],
    AUTHORITY["EPSG","7406"]]

COMPOUNDCRS["NAD27 + NGVD29 height (ftUS)",
    GEOGCRS["NAD27",
        DATUM["North American Datum 1927",
            ELLIPSOID["Clarke 1866",6378206.4,294.978698213898,
                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]]],
    VERTCRS["NGVD29 height (ftUS)",
        VDATUM["National Geodetic Vertical Datum 1929"],
        CS[vertical,1],
            AXIS["gravity-related height (H)",up,
                LENGTHUNIT["US survey foot",0.304800609601219]]],
    USAGE[
        SCOPE["Engineering survey, topographic mapping."],
        AREA["United States (USA) - CONUS onshore - Alabama; Arizona; Arkansas; California; Colorado; Connecticut; Delaware; Florida; Georgia; Idaho; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Montana; Nebraska; Nevada; New Hampshire; New Jersey; New Mexico; New York; North Carolina; North Dakota; Ohio; Oklahoma; Oregon; Pennsylvania; Rhode Island; South Carolina; South Dakota; Tennessee; Texas; Utah; Vermont; Virginia; Washington; West Virginia; Wisconsin; Wyoming."],
        BBOX[24.41,-124.79,49.38,-66.91]],
    ID["EPSG",7406]]

GEOGCS["GCS_North_American_1927",
    DATUM["D_North_American_1927",
        SPHEROID["Clarke_1866",6378206.4,294.978698213898]],
    PRIMEM["Greenwich",0.0],
    UNIT["Degree",0.0174532925199433]],
VERTCS["NGVD_1929",
    VDATUM["National_Geodetic_Vertical_Datum_1929"],
    PARAMETER["Vertical_Shift",0.0],
    PARAMETER["Direction",1.0],
    UNIT["US survey foot",0.304800609601219]]

proj4.defs("EPSG:7406","+proj=longlat +datum=NAD27 +vunits=us-ft +no_defs +type=crs");

{
    "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
    "type": "CompoundCRS",
    "name": "NAD27 + NGVD29 height (ftUS)",
    "components": [
        {
            "type": "GeographicCRS",
            "name": "NAD27",
            "datum": {
                "type": "GeodeticReferenceFrame",
                "name": "North American Datum 1927",
                "ellipsoid": {
                    "name": "Clarke 1866",
                    "semi_major_axis": 6378206.4,
                    "semi_minor_axis": 6356583.8
                }
            },
            "coordinate_system": {
                "subtype": "ellipsoidal",
                "axis": [
                    {
                        "name": "Geodetic latitude",
                        "abbreviation": "Lat",
                        "direction": "north",
                        "unit": "degree"
                    },
                    {
                        "name": "Geodetic longitude",
                        "abbreviation": "Lon",
                        "direction": "east",
                        "unit": "degree"
                    }
                ]
            }
        },
        {
            "type": "VerticalCRS",
            "name": "NGVD29 height (ftUS)",
            "datum": {
                "type": "VerticalReferenceFrame",
                "name": "National Geodetic Vertical Datum 1929"
            },
            "coordinate_system": {
                "subtype": "vertical",
                "axis": [
                    {
                        "name": "Gravity-related height",
                        "abbreviation": "H",
                        "direction": "up",
                        "unit": {
                            "type": "LinearUnit",
                            "name": "US survey foot",
                            "conversion_factor": 0.304800609601219
                        }
                    }
                ]
            }
        }
    ],
    "scope": "Engineering survey, topographic mapping.",
    "area": "United States (USA) - CONUS onshore - Alabama; Arizona; Arkansas; California; Colorado; Connecticut; Delaware; Florida; Georgia; Idaho; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Montana; Nebraska; Nevada; New Hampshire; New Jersey; New Mexico; New York; North Carolina; North Dakota; Ohio; Oklahoma; Oregon; Pennsylvania; Rhode Island; South Carolina; South Dakota; Tennessee; Texas; Utah; Vermont; Virginia; Washington; West Virginia; Wisconsin; Wyoming.",
    "bbox": {
        "south_latitude": 24.41,
        "west_longitude": -124.79,
        "north_latitude": 49.38,
        "east_longitude": -66.91
    },
    "id": {
        "authority": "EPSG",
        "code": 7406
    }
}

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=longlat +datum=NAD27 +vunits=us-ft +no_defs +type=crs">
	<Layer srs="+proj=longlat +datum=NAD27 +vunits=us-ft +no_defs +type=crs">
	</Layer>
</Map>

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 7406, 'EPSG', 7406, '+proj=longlat +datum=NAD27 +vunits=us-ft +no_defs +type=crs', 'COMPD_CS["NAD27 + NGVD29 height (ftUS)",GEOGCS["NAD27",DATUM["North_American_Datum_1927",SPHEROID["Clarke 1866",6378206.4,294.978698213898,AUTHORITY["EPSG","7008"]],AUTHORITY["EPSG","6267"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4267"]],VERT_CS["NGVD29 height (ftUS)",VERT_DATUM["National Geodetic Vertical Datum 1929",2005,AUTHORITY["EPSG","5102"]],UNIT["US survey foot",0.304800609601219,AUTHORITY["EPSG","9003"]],AXIS["Gravity-related height",UP],AUTHORITY["EPSG","5702"]],AUTHORITY["EPSG","7406"]]');