This International Standard, within the context of tools and methods of requirements engineering for software and systems product lines : provides the terms and definitions specific to requirements engineering for software and systems product lines and associated member products; defines process groups and their processes performed during product line requirements engineering (those processes are described in terms of purpose, inputs, tasks, and outcomes); defines method capabilities to support the defined tasks of each process; defines tool capabilities to automate/semi-automate tasks or defined method capabilities. This International Standard concerns processes and capabilities of requirements tools and methods for a family of products, not for a single system. This International Standard is not applicable to physical artefacts. Instead, system-level artefacts and software lifecycle artefacts such as requirements documents, architectural data, validation plans, behavioural models, etc. are produced using methods and tools in this International Standard. In the case of the software components of a system, this International Standard can apply twice: once to handle the system elements of the product line and a second time to handle the software elements of the product line, if any. The product line processes are recursive within the different levels of products. NOTE The requirements in this International Standard apply to the family of systems, software or services.