Data flow
Data moving from one part of the system to another. In both notations a data flow is an arrow, labelled with the data it carries.
Easily confused with
How to read it
Yourdon describes flows as curved, directed arrows connecting the processes, standing for the information a process needs as input or produces as output. The name on the arrow says what moves along it, and a flow carries one kind of packet. Notre Dame’s guide calls arrows the movement of data between entities, processes and data stores, and the UKHSA guidance uses arrows for data flow in both notations.
Also searched as: dataflow, data flow diagram data flow, data flow symbol, dfd arrow, dfd data flow.
Look-alikes
A flowchart flowline shows the order of steps, not data moving. A BPMN sequence flow is also an order of steps, and a BPMN message flow is dashed.
Read next
- Next in Data flow diagram symbolsProcessSomething the system does to data: it takes inputs and turns them into outputs. In Yourdon/DeMarco notation a process is a circle, or bubble; in Gane and Sarson notation it is a rectangle with rounded corners.
- The same shape in Tire sidewall markingsRotation arrowAn arrow, often with the word ROTATION, shows which way a directional tire is designed to turn when the vehicle moves forward.
More data flow diagram symbols
The same shape elsewhere
Browse symbols drawn with arrows, curves and waves or letters and numbers.
Sources
- Just Enough Structured Analysis, Ed Yourdon, rev. 2006 (successor to Modern Structured Analysis, 1989), Chapters 4 and 9, Ed Yourdon (yourdon.com), via Internet Archive, Section 4 and 9.1.2
- Approval standards and guidelines: data flow diagram, Guidance on accessing UKHSA protected data, Notation, UK Health Security Agency (GOV.UK), Notation
- Data Flow Diagram (DFD), Business Analysis guide, Common Diagramming Symbols, University of Notre Dame, Common Diagramming Symbols
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 9, 2026. How we research
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