WTSA-04 Resolution 44 (Bridging the standardization gap between developing and developed countries) requires the preparation of guiding documents to assist in the implementation of ITU-T Recommendations that could be used by developing countries in preparing national specific requirements for deploying new networks and services.In this way,developing countries could benefit from an improved capability in the application of standards,while the telecommunication industry,particularly manufacturers and operators,could benefit from the greater involvement of developing countries in the making and application of standards.The main objective of this Guide on the use of the ITU-T Recommendations related to optical fibres and systems technology is to fulfil these requirements from the WTSA.However,the guide could also have a wider use among manufacturers and operators who are not directly involved in the preparation of this group of Recommendations and they could find the guide to be a useful tool both for rapidly focusing on the Recommendation(s) of specific interest and for better understanding the meaning and the objectives of each Recommendation.Recommendations related to the construction of optical cables, to the installation techniques (duct,tunnel, aerial,buried,mini-trench,micro-trench,etc.) and the associated hardware (closures,connectors, cabinets, poles, etc.) are outside the scope of this Guide because they are dealt with in [ITU-T L-Guide].