Assumptions that cannot yet be proven are acceptable if the effect of one being wrong has been assessed and written down; assumptions, stated or implied, are identified and shown to be reasonable and justified for the system and its assurance level. Where a requirement rests on an assumption instead of a traceable parent, validation shows that firm knowledge or a sound justification was obtained later and that any mismatch was resolved; requirements based on assumed parents are identified, traced back and resolved by certification. Assumptions are stated explicitly, disseminated appropriately and confirmed by supporting data; where an error in an assumption could seriously reduce safety, the design may be shown to bound its consequences. Categories to consider include operational and environmental assumptions (for example traffic density, maintenance intervals, cargo, staffing, flight dynamics, air traffic control, performance, procedures, passengers), design assumptions on crew interface, system interface and reliability, serviceability assumptions and installation assumptions, confirmed by review against industry experience and standards, selective testing or inspection of mockups, prototypes or production data. The validation plan defines how assumptions are managed.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.