This reports the Ethertype value assigned to the given service and port hosting this MEP, specific to PBB/PBT-encapsulated services, identifying which Ethertype the backbone frames for this MEP's traffic actually carry. An admin checks this when a PBT-based MEP's frames are being unexpectedly dropped or misclassified by intermediate backbone equipment, since a nonstandard or mismatched Ethertype here could cause exactly that kind of silent frame handling failure. For example, a PBT service whose cienaCesCfmMEPPBTEtype doesn't match what an intermediate backbone switch expects for that traffic class could have its CFM frames quietly dropped in transit despite both endpoints being correctly configured.