EPSG:8050 — MSL height (ft)

VERTCRS[
    "MSL height (ft)",
    BASEVERTCRS[
        "MSL height",
        VDATUM["Mean Sea Level",ID["EPSG",5100]],
        ID["EPSG",5714]
    ],
    DERIVINGCONVERSION[
        "Vertical Axis Unit Conversion",
        METHOD["Change of Vertical Unit",ID["EPSG",1104]],
        ID["EPSG",7813]
    ],
    CS[vertical,1,ID["EPSG",1030]],
    AXIS["Gravity-related height (H)",up],
    LENGTHUNIT["foot",0.3048,ID["EPSG",9002]],
    ID["EPSG",8050]
]

+vunits=ft +no_defs +type=crs

proj4.defs("EPSG:8050", "+vunits=ft +no_defs +type=crs");

{
  "type": "CoordinateReferenceSystem",
  "code": 8050,
  "name": "MSL height (ft)",
  "kind": "vertical",
  "area": "World",
  "unit": "foot",
  "bbox": [
    -90,
    -180,
    90,
    180
  ],
  "proj4": "+vunits=ft +no_defs +type=crs"
}

INSERT INTO spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext)
VALUES (8050, 'EPSG', 8050, '+vunits=ft +no_defs +type=crs', 'VERT_CS["MSL height (ft)",VERT_DATUM["Mean Sea Level",2005,AUTHORITY["EPSG","5100"]],UNIT["foot",0.3048,AUTHORITY["EPSG","9002"]],AXIS["Gravity-related height",UP],AUTHORITY["EPSG","8050"]]');

PROJECTION
  "+vunits=ft"
  "+no_defs"
  "+type=crs"
END

8050=VERT_CS["MSL height (ft)",VERT_DATUM["Mean Sea Level",2005,AUTHORITY["EPSG","5100"]],UNIT["foot",0.3048,AUTHORITY["EPSG","9002"]],AXIS["Gravity-related height",UP],AUTHORITY["EPSG","8050"]]