Recommendation ITU-T G.807 describes the generic functional architecture of the optical media layer that supports the propagation of signals in the context of a transport network. This description is independent of the client characteristic information (CI) that is being carried by a signal in the media network. Amendment 1 removes the dependence on the ITU-T G.694.1 grid, names the reference point between the digital layer and the modulator/demodulator and uses M-AI/Client CI to replace digital-lane/digital-client. Revision 2 changes the name of modulator/demodulator to transmitter/receiver, includes the subcarrier and point-to-multipoint cases.