2016/05/13 by Jonas Eckhardt, J. Eckhardt, Andreas Vogelsang +3 · 1 citation
Computer Science · #Advanced Software Engineering Methodologies #Computer science #Software Engineering Techniques and Practices #cs.SE
paper · pdf · doi:10.1145/2884781.2884788
Proceedings of the 38th International Conference on Software Engineering, 2016
openalex publication_date 2016/05/13 · arxiv created 2016/11/27 · arxiv updated 2016/11/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Non-functional requirements (NFRs) are commonly distinguished from functional requirements by differentiating how the system shall do something in contrast to what the system shall do. This distinction is not only prevalent in research, but also influences how requirements are handled in practice. NFRs are usually documented separately from functional requirements, without quantitative measures, and with relatively vague descriptions. As a result, they remain difficult to analyze and test. Several authors argue, however, that many so-called NFRs actually describe behavioral properties and may be treated the same way as functional requirements. In this paper, we empirically investigate this point of view and aim to increase our understanding on the nature of NFRs addressing system properties. We report on the classification of 530 NFRs extracted from 11 industrial requirements specifications and analyze to which extent these NFRs describe system behavior. Our results suggest that most "non-functional" requirements are not non-functional as they describe behavior of a system. Consequently, we argue that many so-called NFRs can be handled similarly to functional requirements.