In dictionaries:
North American Vertical Datum of 1988
the vertical datum for orthometric heights established for vertical control surveying in the United States based upon the General Adjustment of the North American Datum of 1988.
National Geodetic Vertical Datum of 1929
the official name since 1973 of the vertical datum established for vertical control surveying in the United States of America by the General Adjustment of 1929.
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