IEC 61158-5-12:2010(E) specifies the structure and services of the type 12 IEC fieldbus Application Layer, in conformance with the OSI Basic Reference Model (ISO/IEC 7498) and the OSI Application Layer Structure (ISO/IEC 9545). This second edition cancels and replaces the first edition published in 2007 and constitutes a technical revision. The main change with respect to the previous edition are: bug fixes and editorial improvements.