Towards systematic recycling of systems requirements

Many (technical) systems are not developed from scratch but as an evolution of existing systems. Consequently, a large portion of the system requirements employed can be recycled when building the next version of the product. Usually, this recycling step is performed unsystematically, i.e. simply by copying and modifying complete requirements documents. In this paper, we present in a case study a lightweight requirements recycling approach which evolved from observations and concrete needs of projects at DaimlerChrysler Passenger Car Development. The basic idea of the approach is separation of model-dependent from model-independent requirements on the same level of abstraction. This notion is supported by document structures, criteria for identifying reusable requirements and tool support. The paper presents the core elements of the approach and provides observations and valuable experiences we made in the projects.