The present document defines the information model to be used at the interface between network elements and management systems@ for the management of Radio Relays equipments which use the SDH. The present document defines: - the information model fragment for Radio Relay Network Elements using SDH multiplexing. The present document does not define: - the protocol stack to be used for message communication; - the network level management processes; - the application contexts; - the conformance requirements to be met by an implementation of this information model; - information models for other systems or equipment. The information model defined here (and the corresponding message set) is concerned with the management of network elements@ the equipment by which they are implemented and the functions contained within them. More precisely@ it applies to an equipment domain visible at the element manager to element interface and is only concerned with information available within that domain. Information proper to the domain of a network level management process is not included within this model.