The Product Data Management (PDM) system and its associated terminology have changed over the years. Product Lifecycle Management (PLM) has become the predominant system and tends to overshadow PDM. However, PDM remains relevant and is a system commonly used by design engineers; mainly as a storage place for drawings and a place where drawings can be found for further editing.To obtain full benefit from the PDM/PLM systems, precise definitions are required. Without such definitions, the systems cannot function as they should and they cannot be used optimally. Furthermore, shortcomings in definitions may lead to a situation where the engineering community is unaware of the kind of help the systems can offer.The main focus of this conference paper is definition of some of the terms inherent to PDM/PLM systems and their data.