Provisional GSGS series 4229. Second Edition-AMS 2. Copied from an Italian Istituto Geografico Militare map dated 1932 with principal communications revised using smaller scale maps from 1938 air photos from 1943 and 1944. Compiled by the U.S. Army Map Service in 1944. Road classification is NOT based on reconnaissance, reliability is uncertain. The grid on map series of Yugoslavia, which adjoin or overlap the eastern edge of this series, is computed on the geographicals of the Greek datum. To convert Greek geographicals to the Italian, upon which the grid of this map is based, subtract 1.7 seconds from the latitudes and add 10.6 seconds to the longitudes. The meridians are based on the meridian of Rome, which is 12 degrees, 27 minutes and 7.1 seconds east of Greenwich. Contours at 50 metres interval. North Italy Zone Grid.