This field reports the total number of octets transmitted on this PM instance, exposed here as cienaCesPmExtendedTxRxTotalStatsBinTxTBytes. On this Ciena CES port's PM data, the description for this field is essentially identical to the sibling TxBytes counter ('total number of octets transmitted' vs 'number of octets transmitted'), so in practice it's Ciena's secondary cumulative-labeled egress byte counter for the same PM instance — the two should track each other closely, and any persistent, growing gap between them on this port is itself worth flagging rather than assuming they're simply redundant; and this is the running grand-total counter for the extended Tx/Rx PM group, tallied since the bin's own StartTime (in practice since the PM instance was created or last reset), so treat it as a lifetime tally rather than a per-interval number. For example, a moderately busy port showing 4,700,000,000 total bytes transmitted for this bin would be a plausible, unremarkable reading.