The IMO Performance Standards for ECDIS defines an ENC as;
“The Database, standardized s to content, structure, and format, issued for use with ECDIS by or on the authority of a Government-authorised Hydrographic Office or other relevant government institution, and conforming to IHO standard. The ENC contains all the chart information necessary for safe navigation and may contain supplementary information in addition to that contained in the paper chart (e.g. sailing direction) which may be considered necessary for safe navigation.”
The International Hydrographic Organization (IHO) has developed a series of standards used by national hydrographic offices around the world. Collectively they define the professional, methods used to produced official navigational charts and publications, and their content, including ENC.
The IHO standard which is most relevant to ENC are as follows: