presents an overview and guidance for the IEC 61158 series. It explains the structure and content of the IEC 61158 series; relates the structure of the IEC 61158 series to the ISO/IEC 7498 OSI Basic Reference Model; shows the logical structure of the IEC 61784 series; shows how to use parts of the IEC 61158 series in combination with IEC 61784 series; provides explanations of some aspects of the IEC 61158 series that are common to the parts of the IEC 61158 5 series. It includes the following significant changes from the previous edition: deletion of the former Type 6 fieldbus, a placeholder for a Type 5 fieldbus data-link layer, and the Type 1 application layer for lack of market relevance; addition of new types of fieldbuses: types 11 to 20; generalization of the Type 1 radio, which is seldom used, to a more useful form; additional descriptions explaining the relation of IEC 61158 to the IEC 61784 family of companion profiles and the structure of these profile documents; division of parts 3 through 6 of the third edition into multiple parts numbered 3 1, 3 2, , 3 19; 4 1, 4 2, , 4 19; 5 2, 5 3, , 5 20; 6 2, 6 3, , 6 20; presentation of the service description concepts used in the many application layer service definitions: parts 5 2, 5 3, , 5 20.