Navigators must always remember that C-MAP Electronic charts are produced using official Hydrographic Office (HO) charts and under the controls of an ISO 9001 certified quality system. They are accurate to the best of our knowledge, and any inconsistencies found are generally due to undetectable limitations in the HO charts themselves. C-MAP electronic charts are NOT currently considered legal replacements of official HO charts and so should be used only as supplements to these, together with prudent navigation habits. Where due, Royalty Charges are included in Chart prices and paid to National Hydrographic Authorities.