IEC 61158-6-3:2014 defines the protocol provided to define the wire-representation of the service primitives defined in IEC 61158-5-3, and define the externally visible behavior associated with their transfer. This standard specifies the protocol of the Type 3 fieldbus application layer, in conformance with the OSI Basic Reference Model (ISO/IEC 7498-1) and the OSI application layer structure (ISO/IEC 9545). This third edition cancels and replaces the second edition published in 2010 and constitutes a technical revision. The main changes are: - corrections, in Table 4, Table 5, Table 6, and Table 7; - added references for data types; - corrected state machine in Table 91 and Table 97; - updated macro START_MSAL1M.