The adoption of product lifecycle management (PLM) business approach requires the implementation of PLM systems. Currently there is a wide variety of PLM systems in the market, but the scope differences between existing systems hamper the selection process for manufacturing companies. This paper presents a reference model for PLM systems and discusses a preliminary proposal for the evolution of this model. The main expected applications for the model are: serve as the basis for the comparison of different commercial systems on selection processes at the industry; contribute to the definition of the theoretical scope of PLM systems; serve as reference for software companies to prioritize the inclusion of new features in their systems.