This read-only MacAddress, held on the ComController, identifies which ComPort's downstream RF-transport statistics (ATM transport and HEC errors, errored seconds, corrected FEC, and unavailable seconds) a given stats row reports. This is a separate identifying key from stuEthStatsMacAddr, since it indexes the RF/transport quality table rather than the Ethernet-layer error table for the same STU. For example, when investigating a report of choppy video service rather than a slow-Ethernet complaint, support would look up the row keyed by stuStatsMacAddress to see the STU's transport-layer error stats specifically.