In the implementation stage the abstract network model of the solution is converted into a physical system, represented as a system implementation diagram (SID). The SID shows the system as a scheduler process that calls modules that implement the processes. Datastreams are represented as calls to inverted processes. Database symbols represent collections of entity state-vectors, and there are special symbols for file buffers (which must be implemented when processes are scheduled to run at different time intervals).
The central concern of implementation step is optimization of the system. It is necessary to reduce the number of processes because it is impossible to provide each process that is contained in specification with its own virtual processor. By means of transformation, processes are combined in order to limits their number to the number of processors.