Since 1 January 2000 the whole of Germany has changed its height system over to normal heights based on the datum of the Amsterdam Ordnance Datum, known as the German Mean Height Reference System, DHHN92. At the same time the new NHN is the basis of the United European Levelling Net (UELN), formerly known as the ' or , which standardises the height systems of the European countries. Heights in this system are given in metres above NHN or m (NHN).