For each Level 0 process,
- Draw the input and output flows and the icons to which they connect from the higher level diagram. This forms the skeleton of the diagram. These are called the net inflows and outflows.
- Define the subprocesses by asking, "What are the steps required to do this process?" Then for each step, "Can I separate this from the other steps and do it in isolation?" For each subprocess you isolate, draw a process rec-tangle on the lower level diagram.
- Identify whether data stores are required or not. Add them and, if they are new, name them.
- Identify data flows to complete the diagram. Make sure you provide all and only the information required to perform the process.
- Review the diagram for unnecessary connec-tions and, if found, remove them.
- Update the data dictionary with all new information.
Sumber: Conger, 2008