In order to monitor the effectiveness of the weather and sea bulletins produced and transmitted by Meteorological Services, the World Meteorological Organization (WMO) conducts a biennial survey of users of Maritime Safety Information. The surveys aim to improve the World-wide Met-ocean Information and Warning Service (WWMIWS). Reports from each survey wave are prepared by the JCOMM Expert Team on Maritime Safety Services (ETMSS). The International Hydrographical Organisation (IHO) conducts a survey of users to assess the effectiveness of the World-wide Navigational Warning Service (WWNWS). The WMO and IHO share the results with each other to improve on common elements. The reports for previous surveys are listed below.