The Global Maritime Distress and Safety System (GMDSS) Manual provides, in a single comprehensive publication, an explanation of the principles upon which the GMDSS is based, the radiocommunication requirements and recommendations for its implementation,the operational performance standards and technical specifications to be met by GMDSS equipment, and the procedures for and method of operation of the various radio services which form the GMDSS and the Master Plan for the GMDSS.