IEC 61158-3-18:2010(E) specifies procedures for the timely transfer of data and control information from one data-link user entity to a peer user entity, and among the data-link entities forming the distributed data-link service provider; procedures for giving communications opportunities to all participating DL entities, sequentially and in a cyclic manner for deterministic and synchronized transfer at cyclic intervals up to one millisecond; procedures for giving communication opportunities available for time-critical data transmission together with non-time-critical data transmission without prejudice to the time-critical data transmission; procedures for giving cyclic and acyclic communication opportunities for time-critical data transmission with prioritized access; procedures for giving communication opportunities based on standard ISO/IEC 8802-3 medium access control, with provisions for nodes to be added or removed during normal operation; the structure of the fieldbus DLPDUs used for the transfer of data and control information by the protocol of this standard, and their representation as physical interface data units. This second edition cancels and replaces the first edition published in 2007 and constitutes a technical revision. The main changes with respect to the previous edition are: - Editorial improvements and Addition of cyclic data segmenting.