GSGS series 4228. First Edition. Italian Istituto Geografico Militare map dated 1934 and photolithographed by the British Ordnance Survey in 1943. The meridians are based on the meridian of Rome, which is 12 degrees, 27 minutes and 7.1 seconds east of Greenwich. The graticule on this sheet is on the French system. To convert to the Italian system deduct 1.5 seconds from the French latitudes and 8.5 seconds from the French longitudes measured from Greenwich. Contours at 20 metres (V.I.). French Lambert Grid (Southern).