Within a given modeling platform, modeling tools, such as model editors and transformation engines, interoperate efficiently. They are generally written in the same general-purpose language, and use a single modeling framework (i.e., an API to access models). However, interoperability between tools from different modeling platforms is much more problematic.In this paper, we propose to leverage fUML in order to address this issue by providing a common execution language. Modeling frameworks can then be abstracted into generic actions that perform elementary operations on models. Not only can user models benefit from a unified execution semantics, but modeling tools can too.We support this proposal by showing how it can apply to a model transformation engine. To this end, a prototype compiler from ATL to fUML has been built, and is described. Finally, we conclude that fUML has some useful properties as candidate common execution language for MDE, but lacks some features.