Chart No. 1

Chart No. 1 is the reference booklet that lists the symbols, abbreviations, and terms used on nautical charts, published jointly by NOAA and NGA for US charts with an equivalent UKHO publication NP 5011 for Admiralty charts. It is not a chart but a legend, organized by the international sections from IHO chart specifications, covering topography, depths, seabed, buoys and beacons, lights, services, and the cross-reference between paper symbols and ENC symbology under IHO S-4 and the S-100 presentation library. The navigator uses it to decode any unfamiliar symbol, sounding convention, or abbreviation on the chart in use.