Recommendation ITU-T G.9804.1 serves as a guide for the development of higher speed passive optical network (PON) systems, by identifying sets of applications that can be addressed by a particular system and defining the requirements for each of those systems. It is anticipated that they may have several distinct systems, such as higher speed single channel (TDMA PON), higher speed multi-channel (TWDM PON), and higher speed point to point overlay PONs. Amendment 1 to Recommendation ITU-T G.9804.1 includes additional requirements for higher speed PON, including slicing requirements for higher speed PON, optional Flexible FEC requirement in the upstream direction, and elimination of 10 Gbit/s upstream rate requirement. Amendment 2 to Recommendation ITU-T G.9804.1 includes additional requirements for higher speed PON, including complementary for co-existence scenario of three generation PON systems.