IEC 61158-6-12:2014 defines the protocol provided to define the wire-representation of the service primitives defined in IEC 61158-5-12, and define the externally visible behavior associatedwith their transfer. This standard specifies the protocol of the Type 12 fieldbus application layer, in conformance with the OSI Basic Reference Model (ISO/IEC 7498-1) and the OSI application layerstructure (ISO/IEC 9545). This third edition cancels and replaces the second edition published in 2010 and constitutes a technical revision. The main changes are:- bug fixes;- editorial improvements;- support of Explicit Device Identification added in ESM.