The 66 is a general description of the architecture of a workflow management system used by the WFMC, in which the main components and the associated interfaces are summarized. The workflow enactment service is the heart of a workflow system which consists of several 67 . In a workflow system, a process is specified using the process definition tool. Usually, processes are defined in terms of a 68 , which consists of 69 indicated using a circle, and 70 shown as a rectangle. These two components can be linked by means of a directed arc.