Conceptual modeling is fundamental within information system engineering. However, it is still difficult to share models, to find reference models or to reuse suitable existing models. Motivated by the Open Model Initiative this paper presents a Meta Modeling Framework for the description of reference models in order to support both common use of existing models and development of new models. This work targeted to specify significant categories and attributes that allow representing knowledge about reference models with an appropriate abstraction level and granularity. The methodological approach and the framework are presented and design decisions are discussed. The usage of the framework is exemplarily sketched.