In our everyday practice of model-based systems engineering in various branches of industry, we repeatedly encounter the question of precise and easy-to-handle versioning of models. This question is becoming increasingly important due to legal regulations, stricter safety regulations and the significant increase in product variants. Therefore, we are responding to a frequently expressed wish and answering the question in this white paper as to whether clean versioning is possible at all when modelling complex cyber-physical systems. To do this, we first look at what constitutes a complex system and why clean release is more difficult today when modelling such systems. Then we turn to practical matters by analysing the versioning process in more detail and describing the resulting requirements for tools. Finally, in the summary you will find the recommendations for achieving clean model versioning based on our decades of experience. So follow us on our journey into the land of unlimited variants and learn how to always keep them safely under control with the help of clean versioning.