By a notation on its Certificate of Class. Each classification society has its own system of character symbols, figures and letters. A tanker classed by Lloyd’s Register, for example, might be described by the notation “+100A1 Oil Tanker ESP LMC UMS IGS ICE CLASS IB”, while a cruise ship classed by Det Norske Veritas (DNV) might have the notation “+1A1 Passenger Ship E0, ICE-1C, COMF-V (cm) 1, W1”.