VERTCRS["EGM84 height",
    VDATUM["EGM84 geoid"],
    CS[vertical,1],
        AXIS["gravity-related height (H)",up,
            LENGTHUNIT["metre",1]],
    USAGE[
        SCOPE["Geodesy."],
        AREA["World."],
        BBOX[-90,-180,90,180]],
    ID["EPSG",5798]]