The concept of balancing states that all the incoming flows to a process and all the outgoing flows from a process in the parent diagram should be preserved at the next level of decomposition.
Process decomposition lets you organize your overall DFD in a series of levels so that each level provides successively more detail about a portion of the level above it.
The goal of the balancing feature is to check your system internal consistency, which is particularly useful as different levels of expertise are generally involved in a project.
When you decompose a process, PowerDesigner helps you initialize, in the sub diagram, the objects from the upper-level to link to the sub-process. PowerDesigner automatically retrieves global objects, such as external entities or data stores and creates object shortcuts, if need be.
The following example shows a top level DFD, in which we are going to decompose the Collect Payment process:
The following example shows the default sub-process diagram of the Collect Payment decomposed process containing its related objects coming from the upper-level. Then, you have to link the objects. Each object you link afterwards to the parent process in the upper-level is automatically displayed in the sub-process diagram:
In addition, PowerDesigner ensures, using balancing checks, that each data on flows or in data stores in the upper-level exist in the sub-diagram.