Recommendation ITU-T G.9806 describes a higher speed bidirectional single fibre point-to-point optical access system than the data rate in existing ITU-T point-to-point access systems. It supports 10 Gbit/s for the optical access services including the optical distribution network (ODN) specification, the physical layer specification, services requirements and the operation, administration and maintenance (OAM) specification. Amendment 1 added support for 25 Gbit/s. Amendment 2 added support for 50 Gbit/s. Amendment 3 adds support for 100 Gbit/s, Optical Path Loss budget Classes SL (0-10 dB), SU (5-15 dB) and BL (10-20 dB).