Abstract. As part of the AMMA project (ATLAS Model Management Architecture), we are currently building several model management tools to support the tasks of modeling in the large and of modeling in the small. The basic idea is to define an experimental framework based on the principle of models as first class entities. This allows us to investigate issues of conceptual and practical interest in the field of model management applied to data-intensive applications. By modeling in the small, we mean dealing with model and metamodel elements and the relations between them. In this sense, ATL (ATLAS Transformation Language) allows expressing automatic model transformations. We also motivate the need for the "ModelWeaver" which handles fine-grained relationships between elements of different metamodels with a different purpose than automatic model transformation. By modeling in the large, we mean globally dealing with models, metamodels and their properties and relations. We use t...