List IV contains important information for the mariner in relation to radiocommunications, including the GMDSS (Global Maritime Distress and Safety System). Detailed information such as the frequencies for transmitting and receiving, in addition to geographical coordinates, is provided for maritime coast radio stations, including those assuming watch-keeping using digital selective calling (DSC) techniques and radiotelephony. List IV also supplies details of additional services such as medical advice, navigational and meteorological warnings, MSI (Maritime Safety Information), AIS (Automatic Identification System), meteorological bulletins and radio time signals, along with the hours of service and operational frequencies, information on port stations, pilot stations, coast Earth stations, VTS stations, contact information of RCC (Rescue Coordination Centers), SAR agencies, Navarea coordinators and AtoNs (AIS Aids to Navigation).
As stipulated in Appendix 16 to the RR, this List shall be provided to all ship stations for which a Global Maritime Distress and Safety System (GMDSS) installation is required by international agreement.

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