Letters may also appear to the sides of the mark indicating the classification society that has surveyed the vessel's load line. The initials used include AB for the American Bureau of Shipping, BV for Bureau Veritas, VL for DNV GL, IR for the Indian Register of Shipping, LR for Lloyd's Register, NK for Nippon Kaiji Kyokai and RI for the Registro Italiano Navale. These letters are approximately 115 millimetres in height and 75 millimetres in width.[9] The load line length is referred to during and following load line calculations.