This object (PmBinState) reports the validity/lifecycle state of this particular bin's counters. On this completed 15-minute bin for this pseudowire, State is the admin's only way to know, after the fact, whether that specific historical window's counts are trustworthy or were invalidated partway through, since trending error counts across bins needs to exclude or flag any bin marked invalid rather than treating a low count as good news. For example, if this pseudowire rebooted partway through this 15-minute interval, State on that bin would come back as something other than a normal/valid value, warning the admin not to read the low error counts as proof the link was actually healthy that period.