This is the cumulative outbound frames discarded counter: counts FC frames this port had queued to transmit but dropped instead of sending, generally because the far end stopped granting credit or the link went down mid-queue. On one specific historical error-statistics snapshot for an FC port, this is the lifetime tally, so a spike here usually tracks a flapping or congested downstream link rather than anything wrong with this port's own hardware. For example, a fabric uplink discards 15 outbound frames in the same minute its peer switch logs a brief loss of sync, then discards return to zero.