In many cases model based software and systems development is done by dispersed groups of developers. Therefore the diffing and merging of different model versions is very important. Konrad Wieland explains in his powerpoint slides what possibilities Enterprise Architect offers to meet this challenge. But only the fine-grained 3-way diffing algorithm that considers the model’s graph structure allows an exact comparison between two models. This 3-way comparison for models that includes the basis version has been realized in LemonTree. It enables calculation of changes in the current model versions; for each version it is calculated which property of a model element has changed. These changes are presented to the user in an intuitive, easy-to-understand fashion.