Research on information visualization has so far established an outline of the information visualization process and shed light on a broad range of detail aspects involved. However, there is no model in place that describes the nature of information visualization in a coherent, detailed, and well-defined way. We believe that the lack of such a lingua franca hinders communication on and application of information visualization techniques. Our approach is to design a declarative language for describing and defining information visualization techniques. The information visualization modelling language (IVML) provides a means to formally express, note, preserve, and communicate structure, appearance, behaviour, and functionality of information visualization techniques and applications in a standardized way. The anticipated benefits comprise both application and theory.