This read-only gauge counts packets detected with an unexpected size or a bad header stack on the TDMoPSN pseudowire. An admin monitors it to catch transport-layer corruption or misconfiguration in the packet-switched network carrying the TDM traffic, separate from sequencing or timing problems. For example, a nonzero and growing count here would point a technician toward checking for MTU mismatches or corrupted encapsulation somewhere along the pseudowire's path.