An electronic navigational chart is an official database created by a national hydrographic office for use with an Electronic Chart Display and Information System (ECDIS). An electronic chart must conform to standards stated in the International Hydrographic Organization (IHO) Special Publication S-57 before it can be certified as an ENC. Only ENCs can be used within ECDIS to meet the International Maritime Organisation (IMO) performance standard for ECDIS. ENCs are available through Regional Electronic Navigational Chart Coordinating e (RENCs) and national electronic chart centers. Distributors like the United Kingdom Hydrographic Office then distribute these to chart agents. In July 2008, the first mandatory requirements for the use of ENC and ECDIS became international law. IHO Special Publication S-63 developed by the IHO Data Protection Security Working Group is used to commercially encrypt and digitally sign ENC data. Chart data is captured based on standards stated in IHO Special Publication S-57, and is displayed according to a display format stated in IHO Special Publication S-52 to ensure consistency of data rendering between different systems. IMO proposed compulsory carriage of ECDIS and ENCs on high speed crafts from 1 July 2008 onwards for all new crafts, and from 1 July 2010 onwards for existing crafts. More you can find on http://www.iho.int ENC & ECDIS Section.