Display characteristics While manufacturers of electronic chart systems have designed their own proprietary colours and symbols, the IMO Performance Standard requires that all IMO approved ECDIS follow the International Hydrographic Organisation (IHO) Colour & Symbol Specifications. These specifications are embodied in the ECDIS Presentation Library. Their development was a joint effort between Canada and Germany during the 1990s. In order for ECDIS to enhance the safety of navigation, every detail of the display should be clearly visible, unambiguous in its meaning, and uncluttered by superfluous information. The unofficial ECS’s continue to be free to develop independent of the IHO control. In general they seek to emulate the look of a traditional paper chart.