| Abbreviation |
Class
of light |
Illustration Period shown
 |
|
| International |
National |
| F |
F |
Fixed |
 |
 |
| Occulting
(total duration of light longer than total duration of darkness) |
| Oc |
Oc |
Single-occulting |
 |
 |
Oc (2)
Example |
Oc (2) |
Group-occulting |
 |
 |
Oc (2+3)
Example |
Oc (2+3) |
Composite group-
occulting |
 |
 |
| Isophase
(duration of light and darkness equal) |
| Iso |
Iso |
Isophase |
 |
 |
| Flashing
(total duration of light shorter than total duration of darkness) |
| Fl |
Fl |
Single-flashing |
 |
 |
Fl (3)
Example |
Fl (3) |
Group-flashing |
 |
 |
Fl (2+1)
Example |
Fl (2+1) |
Composite group-
flashing |
 |
 |
| LFI |
LFI |
Long-flashing (flash
2 s or longer) |
 |
 |
| Quick
(repetition rate of 50 to 79 - usually either 50 or 60 - flashes per
minute) |
| Q |
Q |
Continuous quick |
 |
 |
Q (3)
Example |
Q (3) |
Group quick |
 |
|
| IQ |
IQ |
Interrupted quick |
 |
 |
| Very quick
(repetition rate of 80 to 159 - usually either 100 or 120 - flashes
per minute) |
| VQ |
VQ |
Continuous very
quick |
 |
 |
VQ (3)
Example |
VQ (3) |
Group very quick |
 |
|
| IVQ |
IVQ |
Interrupted very
quick |
 |
|
| Ultra quick
(repetition rate of 160 or more - usually 240 to 300 - flashes per
minute) |
| UQ |
UQ |
Continuous ultra
quick |
 |
|
| IUQ |
IUQ |
Interrupted ultra
quick |
 |
|
|
Mo (A)
Example |
Mo (A) |
Morse Code |
 |
|
| F Fl |
F Fl |
Continuous ultra
quick |
 |
 |
| Al. WR |
AIWR |
Alternating |
 |
 |
