Supplement 50 to ITU-T G-series Recommendations provides an overview of the family of DSL Recommendations. It describes how the various DSL Recommendations are related. This Supplement also defines a generic system reference and a protocol reference configuration for DSL Recommendations and relates it to the system reference models of the DSL Recommendations.This Supplement integrates and replaces Recommendation ITU-T G.995.1(2001) and its Amendment 1. It also includes more clauses and text with regard to Recommendations ITU-T G.992.3, ITU-T G.992.4, ITU-T G.993.2, ITU-T G.993.5, ITU-T G.998.1, ITU-T G.998.2, ITU-T G.998.3 and ITU-T G.998.4.