Classification of primary studies according to research type

This supplementary material contains a classification table of the 38 primary studies analyzed in a systematic literature review on Software Product Management (SPM). The classification follows the research type taxonomy proposed by Wieringa et al. (2006), grouping the studies into Solution Proposal, Validation Research, Evaluation Research, Philosophical Paper, and Experience Report. For each category, the table includes a technical description, the number of associated studies, and the identifiers of the primary studies assigned to that category. The purpose of this material is to provide traceability, transparency, and reproducibility for the research-type classification used in the review.