This Multi-Source Agreement (MSA) defines 4x200 Gbps wavelength division-multiplex (WDM) optical interface for 800 Gbps optical transceivers for Ethernet applications. Forward error correction (FEC) is suggested to be implemented in the module to ensure reliable system operation. Two transceivers communicate over single mode fibers (SMF) of length from 2 meters to at least 2 kilo-meters. The transceiver electrical interface is not specified by this MSA but can have, for example, eight lanes or four lanes in each direction with a total signaling rate of 800 Gbps. A variety of form factors for the 4x200G-FR4 transceivers are possible and none are precluded by this MSA.