Function

Function consists of specific or discreet actions required by a system to achieve an objective (e.g. an operation that a system must perform in order to accomplish its mission, such as a maintenance action required to restore a system to operation). 
        Such actions may be accomplished through the use of equipment, personnel, facilities, firmware, software, or a combination thereof. In a broader sense, the term function refers to what is expected to be incorporated into each system rather than how the system accomplishes its objective. 
        This makes for a more performance-based system and allows for a broad range of techniques to be used to accomplish the performance objectives. This, in turn, maximizes scalability while preserving standardization of results across the aviation organization communities.