Once aircraft functions are allocated, system functions are defined by their role in the aircraft architecture, in terms of what the system must achieve rather than how, including intended actions, prevention of undesired actions and outputs used by other systems. Using the allocations and the classification of each related failure condition, the project works out the system requirements needed to achieve the safety objectives; derived requirements and new assumptions appear along the way and can feed back into the aircraft-level requirements. The result is a requirement set per system with its interfaces, carrying the safety requirements and the assurance levels coming from the PASA, every input having a stated source and every output a stated destination.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.