(excerpt from Regulations about way of marking of waterways and aids to navigation)
Special marks that indicate specific areas, facilities or features that are drawn and described in the official maritime navigation charts and publications and published in the "Notice to Seafarers" are used to mark:
- system for collecting hydro meteorological and oceanographic data at sea
- traffic separation, where the use of marks provided for in this Regulations may cause confusion
- spoil ground
- military exercise zones
- laid submarine cables, pipelines and outfalls
- zones of sports and other activities
- mariculture zones
- boundaries of anchorage areas
- offshore structures.
Special marks are yellow, and their shape must be different from other marks provided for in the Regulations.
Special marks may carry a yellow »X« topmark.
Special marks may be lettered or numbered to indicate their purpose.
The light of the special marks is yellow of any rhythm, but different from the rhythms specified for the cardinal (basic) system, isolated danger marks and safety water marks.
NAUTICAL CHARACTERISTICS OF SPECIAL MARKS
||Any, but different from other shapes of navigational marks
|Topmark (if any)
||Yellow »X« shape
|Light (if any)
||Any other than rhythm of cardinal marks, isolated danger marks and safety water marks