(a) An electric light must have a flash characteristic of the International Morse Code for S-O-S and, under design conditions,

1. (1) Each short flash must have a duration of 1/3 second;
2. (2) Each long flash must have a duration of 1 second;
3. (3) The dark period between each short flash must have a duration of 1/3 second;
4. (4) The dark period between each long flash must have a duration of 1/3 second;
5. (5) The dark period between each letter must have a duration of 2 seconds;

6. (6) The dark period between each

   S-O-S signal must have a duration of 3 seconds.