This read-only object reports the plesiochronous buffer fill level as a percentage between 1 and 99, returning 0 if the demodulator is unlocked and -1 if the buffer is disabled. This shows how full the timing buffer, sized via cdm570RxBufferSize, currently is relative to its total capacity, so a fill level sitting persistently near 0% or 99%, rather than hovering near the middle around 50%, warns that the buffer is close to underflowing or overflowing and due for a recentering -- the CDM-570 equivalent concern to what cdd564RxRecenterBuffer addresses on the CDD-564. An admin who notices this value has drifted to 92% and is still climbing on an otherwise healthy link would consider recentering the buffer proactively before it actually overflows and causes a disruptive slip.