A workflow consists of a collection of activities which support a specific business process; classical examples range from claim management in an insurance company to production scheduling in a manufacturing company to patient care management and support within an hospital. In conventional workflow systems, each business process is separately specified and autonomously supported by a workflow management system, which drives and assists computer-supported activities. However, business processes often interact with each other; in particular, activities which are performed in the context of one process may influence activities of a different process in a way that, laying“between” the two processes, is quite difficult to formalize and understand.