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- A context diagram is a diagram that illustrates how the system works from start to finish. Anyone who views the context diagram should be able to understand at a high-level what is happening within how data is flowing throughout the system.
Data Flow Diagram Notations:
Title Notation Description Entity 
Entities create or use data. Process 
Process - an activity that transforms or changes data.
Data Store 
Data Store - a place where data is stored.
Data Flow 
Data Flow – the movement of data. Arrows should denote the direction of data flow.
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