Introducing Data Flow Diagram Concepts

The key concepts of the data flow diagram are the following. In addition to PowerDesigner's standard palette, a Data Flow Diagram tool palette is available to let you rapidly create objects specific to the diagram type:

Concept	Tool	Gane & Sarson	Yourdon	Description
Process				Location where data is transformed. See Process.
Flow				Oriented link between objects, which conveys data. See Flow.
Data store				Repository of data. See Data store.
External entity				Source or destination of data. See External entity.
Split/Merge				Splits a flow into several flows or merges flows from different sources into one flow. See Split/merge.

Check Model

You can check your data flow diagram at any time using the Check Model feature that includes Data Flow Diagram specific validation rules. Check model may perform automatic corrections to your model or output errors and warnings that you will have to correct manually.