Normalhöhennull

Normalhöhennull ("standard elevation zero") or NHN is a vertical datum used in Germany.

In geographical terms, NHN is the reference plane for the normal height of a topographical eminence height above mean sea level used in the 1932 German Mean Height Reference System (Deutsches Haupthöhennetz). The plane is in the shape of a quasi-geoid. The reference height is a geodetic, fixed point on the New Church of St. Alexander at Wallenhorst in the German state of Lower Saxony. The geopotential height of this point was calculated in 1986 as part of the United European Levelling Network (UELN), based on the Amsterdam Ordnance Datum.