This Recommendation 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 requirements as well as parameters pertinent to various DSL transceivers. Recommendation G.994.1 is currently an integral part of the start-up procedure for both Recommendations G.992.1 and G.992.2. 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.