In this panel, we consider the role of MEI in providing common structures and meanings for heterogeneous musical practices and notations and, to a lesser extent, uses. Drawing on direct experience of working with particular cultural or historical material, we consider the robustness of the fundamental modelling of MEI, and its challenges and strengths. From a practical standpoint, we evaluate strategies for successfully working with MEI, whether through extension of the standard or linking to it from external data structures. We will engage the community with the problems of standardising musical semantics from a non-CMN (Common Music Notation) perspective, and will start the process of developing recommendations for those who wish to engage with the standard to extend further our range of digitised and shareable musics