Chart 1 : Symbols, Abbreviations and Terms

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Lights - Section P

Light Characters

Ref. Abbreviation Class of light Illustration
IHO Symbology IHO Symbology
10.1 Fixed
10.2 Occulting (total duration of light longer than total duration of darkness)
Single-occulting
Group-occulting
Composite group-occulting
10.3 Isophase (duration of light and darkness equal)
Isophase
10.4 Flashing (total duration of light shorter than total duration of darkness)
Single-flashing
Group-flashing
Composite group-flashing
10.5 Long-flashing (flash 2s or longer)
10.6 Quick (repetition rate of 50 to 79 - usually either 50 or 60 - flashes per minute)
Continuous quick
Group quick
Interrupted quick
10.7 Very quick (repetition rate of 80 to 159 - usually either 100 or 120 - flashes per minute)
Continuous very quick
Group very quick
Interrupted very quick
10.8 Ultra quick (repetition rate of 160 or more - usually either 240 to 300 - flashes per minute)
Continuous ultra quick
Interrupted ultra quick
10.9 Morse code
10.10 Fixed and flashing
10.11 Alternating
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