MetaEdit+ (www.metacase.com) is a commercial tool for defining visual modelling languages. It provides facilities to export models to code, but there is no way to simulate the behaviour of models. This project will investigate the possibilities of adding operational semantics by using the API MetaEdit+ provides. A first step will be to hardcode these semantics in Python, using a local representation of the model that is simulated. After that, it will take a look at graph rewriting for automatic rule generation and execution. The rules will be modelled in MetaEdit+, then exported to Python to be executed. To execute the rules, T-Core will be used.