2.7 Using Diagrams in Digital Support

2.7.1 Understand data flow diagrams (DFDs), their purpose, and when they are used

Data Flow Diagrams (DFDs)
A Data Flow Diagram (DFD) is a visual representation of how data moves through a system. It shows where data comes from, how it is processed, where it is stored, and where it goes next. DFDs are used during system analysis and design to understand, document, and communicate how a system handles data.

2.7.2 Know and understand how data flow is expressed in DFDs

DFD Elements and Symbols
  • Data sources – where data originates (external entities)
  • Data destinations – where data is sent
  • Processes – actions that transform data
  • Data stores – places where data is held
  • Arrows – show the direction of data movement
  • Labels – describe the data being transferred
Standard DFD symbols are defined in Appendix 2 of the specification.

2.7.3–2.7.4 Be able to interpret and create DFDs

Interpreting and Creating DFDs
Interpreting a DFD involves following the arrows to understand how data moves through a system. Creating a DFD requires identifying data sources, processes, data stores, and correctly linking them to reflect real system behaviour.
Online DFD Examples

2.7.5 Understand information flow diagrams (IFDs), their purpose, and when they are used

Information Flow Diagrams (IFDs)
An Information Flow Diagram (IFD) shows how information is communicated between people, processes, departments, or systems. It focuses on who sends information, who receives it, and in which direction it flows. IFDs are often used at a higher level than DFDs.

2.7.6 Know and understand how information flow is expressed in IFDs

IFD Elements
  • Boxes – represent people, departments, or systems
  • Arrows – show the direction of information flow
  • Labels – describe the information being exchanged
Symbols are defined in Appendix 2 of the specification.

2.7.7–2.7.8 Be able to create and interpret information flow diagrams

Interpreting and Creating IFDs
Creating an IFD involves identifying sources and recipients of information and clearly showing the direction of communication. Interpreting an IFD helps identify communication paths, dependencies, and potential bottlenecks.
Online IFD Examples