An explanation of terms and symbols used when updating an ADMIRALTY Standard Nautical Chart

The 'amend' command is used when a feature's position remains the same, but one of its characteristics has changed. Amended information will be accompanied by an 'aml' symbol.

There are five command types used for updating a chart: insert, amend, replace, move, and delete.

The 'move' command is for features whose characteristics or descriptions are unchanged but are being relocated less than 3 cm on the chart. The new position will be shown with an arrow drawn from the original position. If a feature needs to be moved more than 3 cm, 'insert' and 'delete' commands are used instead.

The 'delete' command removes a feature entirely from the chart. Deleted information is marked by double strike-through diagonal and horizontal lines, along with a deletion symbol. For deleting a note, the entire text area is boxed with the title visible and the deletion symbol annotated within the box.

The 'insert' command is used for adding entirely new information to a chart.

The 'replace' command is used when one feature substitutes an existing feature, but their position on the chart is unchanged. Replaced information will be accompanied by an 'rpl' symbol.