Cyber-Physical system (CPS) is a coupling of physical and cyber components with a networked intertwined connection. It involves computational elements able to operate on different scales and interact with each other when a change in context occurs. CPS applications for production are termed Cyber-physical production systems (CPPS). It is a new and foreseeable development, whose degrees of integration has reached a self-deciding function possible in production and reflects the industry 4.0 production paradigm. There is a need of modeling approaches to manage complexities, structural opacities and provide a common understanding of CPPS. This paper addresses the semantic understandings of CPPS inspired by the current developments; it classifies the involved entities and illustrates the relations on different aspects. This will serve as a foundation for CPPS, in particular, by helping to understand the structural ambiguity. The real LS2N-CPPS is a supporting use-case of this research work.