It is of historical interest that it was written instructions in the form of periplus, rather than the paper chart, that are recorded as providing the first form of document to guide marine navigators. Therefore perhaps the wheel has turned full circle when it is the digital information rather than the video display that may provide the basic guidance for the navigation of ships in the future. In 1986, when IMO and IHO set out to develop standards and specifications, it was decided that the product to be specified would have to be equivalent to the paper chart. In so doing they were following the guidance of the SOLAS Convention, which requires charts to be carried in Chapter V Regulation 20 and, in Chapter 1 Regulation 5, permits Administrations to substitute equivalents. Regulation V/20 does not state that the charts to be carried be paper but, until recently, it has been assumed that this is what is meant. What is explicit, is that the charts to be carried are to be ‘adequate, up-to-date and necessary for the intended voyage’. Following this guidance, the IMO/IHO Harmonizing Group attempted to specify an electronic system that would be equivalent to a printed paper document. This proved to be no easy task. It was extremely difficult to claim that an electronic system can be as durable and as generally reliable as a sheet of paper. What if the power breaks down? This and many other questions had to be answered before the standards would satisfy the members of IMO.