In this chapter, we will take a look at how subprocesses are created and combined and how instantiating a process step works.
A process model can include multiple process levels, which create hierarchy in the model. Each process level can be viewed as a separate process, which is part of the top-level process. Process levels are created using subprocesses. Creating a subprocess on one level creates a new process level under the current one. This subprocess can then be modeled in more detail in its own flow chart.
Same process step can be used or referenced in several places in the model. This is especially useful for subprocesses, which are similar in several processes. This is done by instantiating the process step. Two or more subprocesses can also be combined into one single process level.