Abstract
In this paper we suggest that one of the big challenges in development of model-based V&V methodology is bridging the gap between the low-level user guides of V&V tools and the high-level text-book descriptions of model-driven development methodologies. As a step towards mitigating this we suggest a structure for V&V methodology with three layers: a bottom level with usage of specific V&V techniques, a middle level with V&V method patterns, and a top level with overall development methodology. Within this structure we suggest that the middle level is often missing in presentations of model-based V&V and in presentations of model-driven development methodologies, and is where the need for development is the greatest.