Hydrographic Datum : A datum used for referencing depths of water and the heights of predicted tides or water level observations. Same as chart datum. See: Datum
National Oceanic and Atmospheric Administration NOAA, Tide and Current Glossary, National Ocean Service, CO-OPS, Products and Services N/OPS3, Silver Spring, MD, USA 1999. http://co-ops.nos.noaa.gov/publications/glossary2. pdf, (ND/ Tide and Current - Amer) {830}
