SURE: Structure for Unambiguous Requirement Expression in Natural Language

This study presents three structures for clearly expressing functional requirements (FRs) and quantitative non-functional requirements (qt-NFRs). Expressing requirements with these structures will allow the understanding of requirements by stakeholders and software developers. The first structure is the SURE format, which is composed of three main sections: a title, a short definition, and a detailed description. The second proposed structure is a template to facilitate the definition of the title and description of unambiguous FRs. It is based on the application of CRUD operations on a certain entity, calling it the “CRUDE” structure. Finally, the third structure serves as a template to make it easier to clearly define the description and title of qt-NFRs. It is based on the application of system properties to computer events or actions, calling it the “PROSE” structure. In this, it is very important to specify those metric values that are desired or expected by the stakeholder. To know how much the definition of FRs and qt-NFRs improved when the proposed structures were used, 46 requirement specification documents elaborated as homework by students of the “Requirement Engineering” course offered at the University of Guayaquil between 2020 and 2022 were evaluated by five experts with more than 10 years of experience in software development for Ecuadorian companies. The findings showed that students reduced the percentage of unambiguous FRs and qt-NFRs from over 80% to about 10%. In conclusion, the findings demonstrate how crucial the three structures proposed in this paper are to helping students develop the ability to clearly express requirements.