Reconfigurable Manufacturing Systems (RMS) have emerged as a promising approach to address the dynamic demands and uncertainties in modern manufacturing. However, the lack of a comprehensive and universally accepted definition of the notion of configuration in RMS poses challenges for researchers and practitioners. This research article aims to bridge this gap by suggesting a core reference model for RMS, allowing to exhibit a generic modelling of configurations. The article critically examines existing definitions and approaches to configuration, providing a comprehensive overview of the different dimensions and components of configuration in RMS. By addressing the lack of a consistent understanding of configuration in RMS, this article contributes to the development of a shared knowledge base and paves the way for further advancements in the field. It also highlights the importance of establishing a clear and holistic definition of configuration for effective implementation and utilization of RMS in practice.