This ÖVE/ÖNORM define in an abstract way the externally visible service provided by the Type 15 fieldbus application layer in terms of a) an abstract model for defining application resources (objects) capable of being manipulated by users via the use of the FAL service, b) the primitive actions and events of the service; c) the parameters associated with each primitive action and event, and the form which they take; and d) the interrelationship between these actions and events, and their valid sequences. The purpose of this part of IEC 61158 is to define the services provided to 1) the FAL user at the boundary between the user and the Application Layer of the Fieldbus Reference Model, and 2) Systems Management at the boundary between the Application Layer and Systems Management of the Fieldbus Reference Model. This part of IEC 61158 specifies the structure and services of the Type 15 IEC fieldbus Application Layer, in conformance with the OSI Basic Reference Model (ISO/IEC 7498) and the OSI Application Layer Structure (ISO/IEC 9545). FAL services and protocols are provided by FAL application-entities (AE) contained within the application processes. The FAL AE is composed of a set of object-oriented Application Service Elements (ASEs) and a Layer Management Entity (LME) that manages the AE. The ASEs provide communication services that operate on a set of related application process object (APO) classes.