Today’s enterprise information and cooperation systems are numerous and diverse. Users have problems of information overload, task interruption and media discontinuity. A unification approach of existing systems would be supportive to overcome these issues by reducing the variety and thereby the complexity. A process of unification starts with the comprehension of existing systems belonging to the virtual environment, by modeling them. The second step is the unification on the model layer followed by the last step, the design of the user interface. This paper will present the first step, a meta-model for cooperation systems, which applies concepts used in professional groupware systems as well as social media platforms. Major elements and concepts of cooperation systems will be identified to provide a basis for the unification of the virtual environment.