This document gives guidance on the accuracy, installation, calibration and verification of automatic level gauges (ALGs), both intrusive and non-intrusive, for measuring the level of petroleum and liquid petroleum products having a Reid vapour pressure less than 100 kPa, transported aboard marine vessels (i.e. tankers and barges). This document gives guidance for buyers and sellers who mutually agree to use marine ALGs for either fiscal and/or custody transfer applications. This document is not applicable to the measurement of level in refrigerated cargo tanks. NOTE            For information on the measurement of level in refrigerated cargo tanks, please see ISO 18132-1 and ISO 18132-3.