The purpose of this Recommendation is to provide a framework for coordination among the various activities in ITU-T on Optical Transport Network (OTN), in order to ensure that Recommendations covering the various aspects of OTN be developed in a consistent and exhaustive way. As such, this Recommendation provides references for definitions of high-level characteristics of OTN, along with a description of the relevant ITU-T Recommendations, together with the time-frame for their development (which are either already prepared, or under development). Note that the development of many of these Recommendations will be phased to address the pace of technology.