Definition
Lateral marks are meaningless without a reference direction. The convention is the direction taken when approaching a harbour, river or estuary from seaward, or, in open coastal waters, the direction defined by the relevant authority and printed on the chart as a magenta arrow, often with two dots for the port side. Around landmasses the direction commonly runs clockwise. On a passage against the convention, port-hand marks are left to starboard and vice versa.
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