Patterns and Requirements Reuse. Requirements reuse consists on taking advantage of requirements knowledge obtained from previous IT projects and later on using this knowledge in a new one. Requirement patterns are assets that provide a structured representation to reuse knowledge about specific requirements. Other assets associated to the term requirement pattern are not considered in this summary since they are not the target of the OpenReq project. Firstly we include here a summary of the existing approaches to requirements reuse, and after that a summary of the practical experiences presented in the literature of the application of requirement reuse and patterns. For a detailed description of the state of the art see deliverable D5.1. The existing proposals of requirements reuse can be mainly characterized by: the part of a requirements specification that they allow to reuse, the language used to express the requirements to be reused, the size of the part of the specification that can be reused, the abstraction of the knowledge to reuse, and the scope where the reuse can be done. ● The proposals classified according the part of a specification that they allow to reuse are proposals that reuse requirements knowledge (e.g., [Xxxxxxx 2007], [Franch et al. 2013]), requirements classification knowledge (e.g., [Panis 2015], [Franch et al. 2013]) and/or requirements interdependencies (e.g., [Xxxxxx et al. 2013], [Xxxxxx et al. 2002]). ● From the proposals that allow to reuse requirements knowledge, they assume that these requirements are expressed in natural language (e.g., [Withall 2007]), use cases (e.g., [Xxxxx et al. 2006], [Dehlinger et al. 2005]), and domain models (e.g., [Xxxxx et al. 2002]). More formal representation of requirements are also used in some approaches, such as i* models (e.g., [Xxxxxxxx et al. 2004]). ● The size of reusable artifacts varies from individual requirements (e.g., [Xxxxxxxx et al. 2012]) to requirement clusters (e.g., [Xxxxxx et al. 2002]), to parts of requirement specifications and even to complete requirement specifications (e.g., [Xxxxx et al. 2006]). ● The abstraction of knowledge to reuse in the proposals varies from no abstraction — such as templates that are natural language sentences with no required structure (e.g., [Xxxxxxxxxxx et al. 2012]) — to a high level of abstraction — for instance in the case of patterns or feature models based on the notion of variability of requirements (e.g., [Xxxxxxx 2007], [Xxxxxxx et al. 1999], [Xxxxxx et al. 2013])....
