Electronic Navigational Chart (ENC) is not an electronic version of paper chart. It is a digital database containing all information necessary for safe navigation. Its content, structure and format are standardized, and its publication has to be authorised by the government hydrographic office.

To access, view and navigate with the Hong Kong ENC, it must be used in conjunction with a type-approved ECDIS, software or devices compatible with the IHO S-57 data format. These ECDIS, software or devices are provided by commercial vendors.

ENC may contain supplementary information more than contained in the paper chart, such as: list of lights, sailing directions. It is for use with the Electronic Chart Display and Information System (ECDIS) for safe navigation: when interfaced with navigational sensors, such as GPS, Automatic Radar Plotting Aid (ARPA) and echo sounder, it can display real-time ship position in relation to topography, charted object, submerged dangers, grounding and collision warnings.