## 4 Results and Discussion
### RQ2: In Which RE Activities Have the CVs Been Reported?
Figure 2: Mentions of requirements engineering (RE) activities where CVs have been used. RQ3: Which Aspects of the Software Development Process, or of the Final Product, Were Affected by the Use of the CV? Each primary study describes the impact by using different key terms, depending on the context in which the CV has been used. For that reason, during data extraction we obtained a broad set of terms related to this research question. In order to facilitate the analysis, we performed a thematic analysis following the guidelines of [48] and grouped all the original 154 impact mentions into 17 categories (listed in Table 10). The first column (Primary papers) shows the ID of the primary paper, the numbers in brackets indicate the quantity of mentions from the same primary paper. The column, Support Level, shows the quantity of impact mentions from our set of selected primary papers. Guidance and understanding is the category that includes a greater number of mentions. The use of CVs, both ontologies and taxonomies, has a positive impact on the development of the software (process) and the final product (system) (S02). In the earlier phases of software development (i.e., requirements engineering) it is crucial to understand what data need to be requested from providers, where and when to capture the data, and what parts of them can be made accessible to different users (S20). Furthermore, a list of potential tasks (data manipulation) can help to overcome elicitation problems. CVs help requirements analysts in the process of understanding the key concepts in the problem space (S53). Problems of understanding typically result from the fact that RE involves a variety of people's expressed needs across different stakeholders. Another source of problems of understanding is the subjective nature of requirements, especially non-functional ones. The CVs provide a common terminology for relevant knowledge, enabling a uniform treatment of data and reducing the chances of missing out key requirements. \begin{table}
\begin{tabular}{l c c} \hline \hline
**Primary Paper** & **Category** & **Support Level** \\ \hline S02, S06, S08, S16, S20 (4), S23, S27, S32, S34, S40, S42, & & \\ S45, S46, S50, S53 (2), S57, S59, S61, S62, S64, S65, S66, & Guidance and understanding & 35 \\ S68, S70, S75, S76 (2), S81, S86, S89 (2). & & \\ \hline S04, S10, S11, S12, S28, S33, S43, S47 (2), S51, S55, S56, & & \\ S72, S77, S84, S85, S86, S89, S90 (2). & & \\ \hline S02, S07, S11, S18, S19, S24, S26, S36, S39, S43, S44 (2), & Identification of conflicts & 18 \\ S46, S49 (2), S50, S84, S86. & & \\ \hline S14, S17, S28, S29, S38, S67, S69, S74, S78, S82, S83, S84, & Completeness, correctness & 14 \\ S88 (2). & & \\ \hline S11, S26, S35, S37, S73, S78, S79, S85, S86, S90. & Quality & 10 \\ \hline S04, S05, S06, S11, S22, S30, S38, S52. & Reusability & 8 \\ \hline S09, S10, S18, S41, S58, S70, S71. & Ambiguity & 7 \\ \hline S02, S13, S25, S62, S68, S69, S87. & Elicitation & 7 \\ \hline S21 (2), S28, S40, S49, S57, S63. & Testing and traceability & 7 \\ \hline S07, S37, S60, S70, S79, S80. & Productivity and time reduction & 6 \\ \hline S03, S31, S57, S65, S87. & Communication & 5 \\ \hline S29, S38, S48, S54. & Consistency & 4 \\ \hline S01 (2), S15, S40. & Evolution and maintainability & 4 \\ \hline S37, S51, S72. & Costs & 3 \\ \hline S12, S27, S74. & Validation & 3 \\ \hline S03 (2) & Control and coordination & 2 \\ \hline S77 & Modelling & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Categories of Impacts. Automation and tool support is the second most cited category. CVs, especially ontologies, can be used as a theoretical foundation for automating some tasks, such as (S04): detecting conflicts, classify requirements or detect defects. Many tools, implementing ontologies and rules, provide support to detect NFR conflicts and inconsistencies (S43). Automatic analysis of natural language requirements and assistance to analysts during requirements specification is another benefit of using CVs.