his WHO volume contains recommended quantities, indications and dosing for 55 medicines listed in the International Medical Guide for Ships 3rd edition. The quantities are based on three types of ships: ocean-going ships with crews of 25–40 and no doctor (Category A); coastal ships with crews of up to 25 that travel no more than 24 hours from a port of call (Category B); and small boats and private craft with crews of 15 or less, and usually travelling no more than a few hours from a port of call (Category C).