This counter tracks the number of STAT PDUs received on this port, per the description, containing the far end's report of its sequenced-data receive state in response to a POLL this port sent. Comparing this to NumPollPduTx tells you whether this port's polls are actually being answered by the peer; if not, this port's own MaxCC unacknowledged-PDU counter will start climbing toward a declared loss of connection. This is the counter to check first when svcAtmConfigQSaalMaxCC-related link resets are happening on this port.