All topographic maps of Namibia are oriented Northward. This is reflected by the orientation arrow placed in the legend. The main arrow indicates the direction of the "geographic" North - also called "true North" -, while the secondary arrow gives an indication about the direction of magnetic North. Magnetic North is the direction read on a magnetic compass. It does not correspond exactly to the geographic north (but rather some 10° West. This angle is called the magnetic declination. The amplitude of magnetic declination varies in place and in time. The value given on the maps is an estimation of the angle of declination in the centre of the map sheet, and its (estimated) evolution for the next few years.