This read-only PerfTotalCount reports the count of octets (bytes) received in valid frames on the DSL port, scoped to the DSL port's current, still-accumulating measurement period (not yet rolled into the interval history). Operationally, it's the byte-level counterpart to the valid-frame count and lets an admin estimate actual downstream data volume rather than just frame counts. For example, an admin can subtract two successive live readings of this counter to estimate the current inbound data rate on the port.