Fig. 6. Graph process for the collaboration diagram of operation processOrder. The

three rules in the upper left section represent the operations, those in the upper right

realize the control .ow between these operations, and the .ve rules in the lower part

are responsible for state transformations (note that attribute values a and p of /d can

be instantiated by new /d since all the rules of the graph process act in a common

context given by the collaboration)