Describing data control in programming languages

The authors describe a multipass, multilayered model of the semantics of the data-control aspect of programming languages, illustrating the model by using it to define the data-control aspect of the language Pascal. The model is an information structure model in which the information structures are defined in a relatively precise manner, using algebraic specification techniques for abstract data types. The use of abstract data types is also the key to the layering of the description: the outermost layer describes the semantics of the language feature, the middle layer contains definitions for the manipulation of the information structures used within the model, and the innermost layer contains precise descriptions of these information structures. The fact that the model is layered allows various potential users of the semantic description to choose a level of detail appropriate to their needs