Bilingual (Chinese and English) paper nautical charts are
produced in accordance with the specifications of the International
Hydrographic Organization (IHO). The positions on the chart
are referred to the WGS84 Datum. The depths are in metres
and reduced to the Chart Datum, which is approximately the
Lowest Astronomical Tide. The buoyage system in Hong Kong
follows the IALA Maritime Buoyage System (Region A), i.e.
Red to Port, Green to Starboard.