MSC and data: dynamic variables

The extension of the MSC language with more advanced data concepts is one of the current topics of discussion in the MSC standardization community. A recent paper at the SAM98 workshop by two of the current authors [2] treated the extension of MSC with static variables. Feasibility of an approach to parameterize the MSC language with a data language was shown. We have extended this research by studying the combination of MSC with a data language containing dynamic variables. Rather than giving a precise proposal of the way in which an actual data language must be added to the MSC language, we discuss options and problems. Choices have to be made, for example with respect to scope, use of variables, and the way of assigning variables. For some particular combination of the options mentioned above, we give a formal operational semantics of the combined MSC/Data language. It is argued that the interface between the data language definition and the MSC language definition should be explicit.