Hierarchical modular modelling in discrete simulation

The increasing use of discrete simulation in modelling large and complex systems brings new challenges. One such challenge is the need to devise ways of developing modular approaches to reduce the complexity of model building and to make such models easier to maintain. This paper discusses an approach, known as selective external modularity, that builds on the work of B.P. Zeigler (1976, 1984, 1990) and others by adding the capacity to cope with emergent behaviour in composite models