Abstract: The invention relates to a system for annotation based model driven software development comprising a source code and a model. The system further comprises an element in said model linked to at least one element in said source code through an annotation. Hereby is achieved to maintain and develop software systems through a model driven development environment and to maintain correspondence between source code and model (including possibility for round-tripping) with a reduced amount of complexity and development effort. Further, it is achieved to have one system/modelling tool able to comprise an entire software system. Further, it is achieved to allow the user to make changes to both the model and the source code.