Provisional GSGS series 4229. First Edition-AMS 1. Copied from an Italian Istituto Geografico Militare map dated 1933 with principal communications revised from Italy Road Map, 1938. Compiled by the U.S. Army Map Service in 1944. Road classification is NOT based on reconnaissance, reliability is uncertain. The grid of Yugoslavia, which adjoin or overlap the eastern edges 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 latitiude and add 10.6 seconds to the longitude The meridians are based on the meridian of Rome, which is 12 degrees, 27 minutes and 7.1 seconds east of Greenwich. Contours interval 50 meters. North Italy Zone Grid.