This counts the total number of valid packets transmitted over this specific pseudowire service instance. Comparing TxPkt on this PW against the remote end's RxPkt (where visible) is how an admin estimates one-way packet loss across the network path carrying this specific service -- 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 50000 -- a concrete count the admin can trend against neighboring bins to judge whether the condition it reflects is worsening.