GSGS series 4228. Second Edition (coloured). Italian Istituto Geografico Militare map dated 1931 and photolithographed by the British Ordnance Survey in 1942. Partially revised using Air Photographs in 1942. The meridians are based on the meridian of Rome, which is 12 degrees, 27 minutes and 7.1 seconds east of Greenwich. Contours at 5 metres (V.I.). South Italy Grid (Blue).