esaProbeHistoryY1731RxDmSamples is a true/false flag, applicable only to Y.1731 probes, that is set when at least one Delay Measurement Reply (DMR) was actually received for a completed interval that has already closed and been archived into the rolling history log. Because a bin can show zero loss or zero delay simply because no reply ever arrived at all, this flag is what lets a technician tell 'the service performed perfectly' apart from 'the measurement never happened' for that specific bin. For example, a technician auditing a month of archived bins can discard the handful where this flag was false, instead of mistakenly averaging in intervals where no Delay Measurement Reply (DMR) was ever received.