Recommendation ITU-T G.994.1 provides a flexible mechanism for digital subscriber line (DSL) transceivers to exchange capabilities and to select a common mode of operation. It includes parameters relating to service and application requirements02/ as well as parameters pertinent to various DSL transceivers. This Recommendation is currently an integral part of the start-up procedure for Recommendations ITU-T G.991.2, ITU-T G.992.1, ITU-T G.992.2, ITU-T G.992.3, ITU-T G.992.4, ITU-T G.992.5, ITU-T G.993.1, ITU-T G.993.2, ITU-T G.993.5, ITU-T G.9701, ITU-T G.9702 and ITU-T G.9711. It is anticipated that future DSL Recommendations will also be able to make use of this Recommendation. Provisions are also included for exchanging non-standard information. Amendment 1 to ITU-T Rec G.994.1 includes the following new material – Add codepoints for the support of G.fastback Recommendation.