Covers standard practice for level measurement of light hydrocarbon liquids onboard marine vessels by automatic tank guages (ATGs). This publication covers pressurized and refrigerated light hydrocarbon liquids. The light hydrocarbon liquids covered in this standard include: liquified petroleum gas (LPG), natural gas liquid (NGL), and other petrochemical liquids where the storage and transportation requirements and the methods of measurement are similar to that for LPG and NGL gauging. This standard also covers the requirements for data collection, transmission and receiving.