This read-only PerfCounter64 counts probe-to-reflector unavailable delta_ts, incrementing when FLR exceeds the availability threshold for 'n' consecutive delta_ts, per its description, the counterpart naming to f3EsaProbeStatsSoamPmExtP2rUnavailableTime. An administrator uses this to record SLA-violating downtime in the outbound direction when working with tooling expecting the standard SOAM-PM delta_ts naming. For example, an operator generating a standards-compliant availability report would cite f3EsaProbeStatsSoamPmExtP2rUnavailableDeltaTs rather than the vendor-named UnavailableTime object for that field.