bitsPortSignalFrequency is a read-write setting indicating the signal frequency of the port, chosen from options such as 100 kHz, 1 MHz, 1544 kHz, 2048 kHz, 5 MHz, 25 MHz, or 50 MHz, and settable only on a port dedicated to producing a variety of frequencies. An administrator sets this to match whatever frequency the connected equipment needs as its reference, rather than the fixed T1/E1 rates used elsewhere in the BITS table. For example, a lab test set requiring a precise 10 MHz -class reference would instead be fed from a port set to the nearest supported frequency such as 5 MHz or 25 MHz depending on what the equipment accepts.