Amendment 1 to Recommendation ITU-T G.984.6 is aimed at defining several additional features or types of reach extender units, including: Wavelength-converting reach extenders. Continuous mode reach extenders. 1:N protected reach extenders.
ITU-T G.984.6 AMD 1-2009 history
2009ITU-T G.984.6 AMD 1-2009 Gigabit-capable passive optical networks (GPON): Reach extension Amendment 1: Wavelength-converting, continuous mode, and 1:N-protected range extenders (Study Group 15)