1.3.10-12 Coding by Flash Rate

No more than two flash rates should be used.

Additional Information:
The differences between the two flash rates should be at least 2 Hz. The slow flash should not be less than 0.8 Hz and the fast flash rate should not be more than 5 Hz. The percentage of time that the image is 'on' should be greater than or equal to the time that it is 'off.' A 50 percent duty cycle is preferred. When a single blink rate is used, the rate should be roughly 2-3 blinks per second with a minimum of 50 msec 'on' time between blinks.