The value of tmnxCpmProtEthCfmPolOpCodeSet specifies a set of Eth-CFM
PDU Opcode values to be matched against the Opcode field of an Eth-CFM
PDU which is subject to rate limiting. At least one Opcode must be
specified (i.e. the empty set is not supported).
This object works in conjunction with tmnxCpmProtEthCfmPolLevelSet, as
described in the tmnxCpmProtEthCfmPolLevelSet DESCRIPTION.