This boolean flag indicates whether the current statistics bin for this access-port QoS shaper represents a complete, trustworthy measurement period. An admin checks this before drawing conclusions from the bin's counters, since an invalid bin, such as one collected right after the port came up, could otherwise look like a period of unusually low congestion. For example, if cmAccPortQosShaperStatsValid is false right after a port reset, the admin would wait for the next full interval before trusting the shaper's tail-drop counts.