Recommendation ITU-T G.9804.2 specifies the common transmission convergence (ComTC) layer of Higher Speed passive optical network (HSP) systems providing optical access for residential, business, mobile backhaul and other applications. This specification defines operation of HSP systems in a manner agnostic of transmission rates, number of operating wavelength channels, and signal modulation. It is intended to be applicable to systems implementing a subset of the specified range of features. An HSP system enables protocol flexibility to support higher performance physical media dependent (PMD) interfaces without impacting the definition of the associated ComTC layer. An HSP system does not require an implementation to support all possible ComTC features. The intent is to provide the definition and behaviour of a ComTC layer independent of line rate, number of wavelength channels, and signal modulation. Actual systems would be based on features chosen for implementation and available supporting technology. The ComTC layer is the protocol layer of the HSP system that is positioned between the PMD layer and service clients. It builds on the ITU‑T G.987.3, ITU‑T G.9807.1, and ITU‑T G.989.3 Recommendations, with modifications to support specific features, primarily rate flexibility, single and multiple wavelength operation, and signal modulation. This Recommendation forms an integral part of the ITU-T G.hsp series of Recommendations (ITU‑T G.9804.1 and applicable PMD Recommendations) that, together with the ONU management and control interface (OMCI), Recommendation ITU-T G.988, specifies a set of access transmission systems. Amendment 3 includs the following updates: modification to bonded XGEM in clause 9, clarification of DWLCH ID in clause 10; modification to the Deactivate_ONU-ID, Channel_Profile, Burst_Profile, and Disable_SN messages in clause 11; deprecation of the 12.5G upstream rate; update to Tables 12-1 and 12-3; clarification on multi-rate ONU activation in clause 12; LOOCi detection update in clause 14; key derivation and switching update in clause 15 and Annex D; the bonded wavelength inter timing update in Annex H; the cipher and key switching procedure in Annex J; and the ONU synchronization state machine update in Appendix X.