IEC 61158-5-20:2010 specifies the structure and services of the type 20 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 is Revised VFD ASE. This bilingual version published in 2012-01 corresponds to the English version published in 2010-08.