This counts seconds in which the emulated TDM circuit carried over this pseudowire experienced at least one qualifying error, such as a lost or malformed packet affecting playback. Because this is measured on the reconstructed TDM side of the pseudowire rather than on the packet network directly, ES on this PW reflects what the attached TDM equipment actually experienced, which can rise even when the underlying packet counters look only mildly degraded -- and this specific object covers a closed 15-minute history bin -- a fixed, final count for one completed interval rather than something still changing. For example, over that completed 15-minute bin, this pseudowire might show this counter at 5 -- a concrete count the admin can trend against neighboring bins to judge whether the condition it reflects is worsening.