of goals, a concept of operations that describes user needs and the operating environment, thorough and testable system requirements, detailed design, implementation, rigorous acceptance testing of the implemented system to ensure it meets the stated requirements (system verification), measuring its effectiveness in addressing goals (system validation), on-going operation and maintenance, system upgrades over time, and eventual retirement. The process emphasizes requirements-driven design and testing. All design elements and acceptance tests must be traceable to one or more system requirements and every requirement must be addressed by at least one design element and acceptance test. Such rigor ensures nothing is done unnecessarily and everything that is necessary is accomplished. The two streams Specification stream The specification stream mainly consists of: User requirement specifications Functional requirement specifications Design specifications Testing stream The testing stream generally consists of: Installation qualification (IQ) Operational qualification (OQ) Performance qualification (PQ) The development stream can consist (depending on the system type and the development scope) of customization, configuration or coding. Applications The V-model is used to regulate the software development process within the German federal administration. Nowadays it is still the standard for German federal administration and defense projects, as well as software developers within the region. The concept of the V-model was developed simultaneously, but independently, in Germany and in the United States in the late 1980s: The German V-model was originally developed by IABG in Ottobrunn, near Munich, in cooperation with the Federal Office for Defense Technology and Procurement in Koblenz, for the Federal Ministry of Defense. It was taken over by the Federal Ministry of the Interior for the civilian public authorities domain in summer 1992. The US V-model, as documented in the 1991 proceedings for the National Council on Systems Engineering (NCOSE; now INCOSE as of 1995), was developed for satellite systems involving hardware, software, and human interaction. The V-model first appeared at Hughes Aircraft circa 1982 as part of the pre-proposal effort for the FAA Advanced Automation System (AAS) program. It eventually formed the test strategy for the Hughes AAS Design Competition Phase (DCP) proposal. It was created to show the test and integration approach which was driven by new challenges to surface latent defects in the software. The need for this new level of latent defect detection was driven by the goal to start automating the thinking and planning processes of the air traffic controller as envisioned by the automated enroute