VERTCRS["HKPD depth",
    VDATUM["Hong Kong Principal Datum"],
    CS[vertical,1],
        AXIS["depth (D)",down,
            LENGTHUNIT["metre",1]],
    USAGE[
        SCOPE["Intermediate stage in transformations - not used otherwise."],
        AREA["China - Hong Kong - onshore."],
        BBOX[22.19,113.82,22.56,114.39]],
    ID["EPSG",7976]]