ITU-T Rec. G.983.1 on Broadband optical access systems based on passive optical networks (PON) describes systems with transmission rates of 155.52 or 622.08 Mbit/s downstream and 155.52 Mbit/s upstream. G.983.1 Amendment 1 allows enhancement to include 622.08 Mbit/s upstream. ITU-T Rec. G.983.3 which describes Broadband Passive Optical Network (B-PON) systems with increased service capability by wavelength allocation could not take account of Amendment 1/G.983.1. This Amendment describes modifications to the requirements for isolation and return loss in G.983.3 made necessary because of the power budget changes needed for 622.08 Mbit/s upstream rate.