Processes, interactions and lifecycle
Data-flow diagram (Yourdon/Gane–Sarson idiom)
Processes, data stores and external entities with the flows between them: where data moves, not who decides.
ddn@1New DDN source
Why use it?
DFDs expose missing flows and orphan stores that a task diagram never shows.
When it helps
Mapping information movement through a system before deciding on implementation.
How to read it
- Every arrow is data in motion, labeled with what it carries.
- Stores are data at rest; a store nobody reads is a question, not a fact.
What you need
- The processes
- The stores
- The flows and their contents
Things to check
- Do not draw control flow — arrows carry data, not instructions.
- Do not let a process have inputs but no outputs.
Scope of this diagram
Flow documentation; no simulation of the data actually moving.
Work with the converted example
- Open the viewer and select
diagram. Inspect the rendered view and its source. - Open the designer. Keep the selected profile and inspect its legal palette and property controls.
- Change one displayed title or an appropriate data value. Apply the edit and check the resulting diagram.
- Run the verifier and review its diagnostics before moving complete content into review.
- Download your edited DDN source to retain the change.
The example uses the indentation-based ddn-next-1 dialect. The language guide explains reusable definitions, dotted data rows and explicit property blocks.