( b ) `` Inland Electronic Navigational Chart ( Inland ENC ) '' means a database , standardised as to content , structure and format , issued for use with inland electronic chart display and/or information systems operated on-board of vessels transiting inland waterways . An Inland ENC is issued by or on the authority of a competent government agency , and conforms to standards initially developed by the International Hydrographic Organization ( IHO ) and refined by the Inland ENC Harmonization Group .