This read-only PerfCounter64 reports the sum of all absolute round-trip jitter samples collected during the current measurement interval, per its description. An administrator, or more typically an NMS, uses this raw sum together with the sample count to (re)compute the average jitter, or with the sum-of-squares object to derive variance. For example, a performance-analysis tool would combine this sum with f3EsaProbeStatsSoamPmExtNumAbsRTJitter to independently recompute the average jitter rather than trusting a single pre-aggregated value.