This amendment provides an enhancement to ITU-T Recommendation G.984.2 to support optical layer supervision and a new optical line termination (OLT) optical interface specification (C+) that can enable a loss budget extension of 4 dB. Also, a modification to the 2.488 Gbit/s downstream extinction ratio is made, to bring it in line with ITU-T Recommendation G.957, and to add some text regarding network timing.