Special marks.
Definition of Special Marks
Marks used to indicate a special area or feature whose nature may be apparent from reference to a chart or other nautical publication. They are not generally intended to mark channels or obstructions where other marks are more suitable.
Some examples of uses of Special Marks:
Ocean Data Acquisition Systems (ODAS) marks;
Traffic separation marks where use of conventional channel marking may cause confusion;
Spoil Ground marks;
Military exercise zone marks;
Cable or pipeline marks;
Recreation zone marks;
Boundaries of anchorage areas;
Structures such as offshore renewable energy installations;
Aquaculture.
Source: IALA
