FOT – Frequency of optimum traffic –“Frequency where the MOFs will be higher on at least 90% of the days of the month at that hour”

–Propagation supported on most days of month

–Not necessarily ‘optimum’ frequency for SNR •HPF – Highest probable frequency –“Frequency where no more than 10% of the hourly MOFs will be higher”

–Frequencies above MUF supported on some days of month