This International Standard deals with the tools and methods of requirements engineering for software and systems product line. The scope of this International Standard is as follows: • provide the terms and definitions specific to requirements engineering for software and systems product lines. • define process groups and their processes performed during product line requirements engineering. Those processes are described in terms of purpose, inputs, tasks, and outcomes. • define method capabilities to support the defined tasks of each process. • define tool capabilities to automate/semi-automate tasks or defined method capabilities. This International Standard does not concern processes and capabilities of requirements tools and methods for a single system but rather deals with those for a family of products. NOTE This International Standard is not suitable for handling physical artifacts. In the Systems arena, the word "Product" must be understood as System-level artefacts, such as requirement documents, architectural data, validation plans, Behavioral Models, etc. In any case, the word "Product" must not be understood as physical items such as electronic boards, mechanical parts or qualified human operators. In the case of the Software components of a Systems, this International Standard can apply twice: once to handle the System-Level Product Line and a second time to handle the Software Part Product Line, if any. The Product Line processes are recursive within the different levels of Products.