For outgoing Service Flows, this object counts the number of Packet Data PDUs forwarded to this Service Flow. For incoming upstream CMTS service flows, this object counts the number of Packet Data PDUs actually received on the Service Flow identified by the SID for which the packet was scheduled. CMs not classifying downstream packets may report this object's value as 0 for downstream Service Flows. This object does not count MAC-specific management messages. Particularly for UGS flows, packets sent on the primary Service Flow in violation of the UGS grant size should be counted only by the instance of this object that is associated with the primary service flow. Unclassified upstream user data packets (i.e., non- MAC-management) forwarded to the primary upstream Service Flow should be counted by the instance of this object that is associated with the primary service flow. This object does include packets counted by docsIetfQosServiceFlowPolicedDelayPkts, but does not include packets counted by docsIetfQosServiceFlowPolicedDropPkts and docsIetfQosServiceFlowPHSUnknowns. This counter's last discontinuity is the ifCounterDiscontinuityTime for the same ifIndex that indexes this object.