The use of simulation has traditionally required a great deal of expertise. Simulation Interfaces to General Purpose Simulation Languages made simulation easier to use. However, for successfully building simulation models, modelling expertise is still required. Macros have been proposed as a tool within Simulation Interfaces which simplify the building of models. A macro in this context should be seen as a group of Simulation Language statements with a data interface to the user. The questions to be answered were: ‘What should a macro do and how should it be implemented?’ The first objective of the work was to specify the macro functionality more tightly and then develop some macros. The wide range of macro applications allows categorising. An attempt was made to classify the different types of macros in a hierarchical structure. Implementation of macros in SIMAN’ª(, showed difficulties such as nesting, attribute sharing, and code connectivity. To make data input for complete models less laborious, generic data interfaces were proposed. A simple model of a manufacturing cell is discussed, to show some of the above mentioned aspects. It became clear that macros could considerably speed up model building. However, bigger macros could reduce modelling flexibility to some extent.
