The primary purpose of the three volumes of the I.A.M.S.A.R (International Aeronautical and Maritime Search And Rescue) manual is to assist the states in meeting their own search and rescue needs, and the obligations they accepted under the convention on international civil aviation, the international convention on maritime search and rescue, and the international convention for the safety of life at sea.
These volumes provide guidelines for a common aviation and maritime approach to organising and providing SAR services. States are encouraged to develop and improvise their SAR services, co-operate with neighbouring states, and to consider their SAR services to be part of a global sar system.
Each IAMSAR manual volume is written with specific SAR system duties in mind, and can be used as a stand-alone document or, in conjunction with the other two volumes as a means to attain a full view of the SAR system.
Good high level intro of IAMSAR manuals