2. Context Diagrams There are three symbols used in these diagrams: Context Diagrams are used in the Analysis and Design phases as an analysis and design tool used to analyse processes occurring in a current information system and also to design a new information system. They help in identifying where problems may be occurring in an information system.

3. Data Flow Data flows describe the data being transferred, not the processing of the data. E.g. “booking” is used rather than “validate booking”. “Validate booking” is a process whereas the “booking” itself is the data. Booking

4. The whole system and a process The oval shape is used to represent the whole information processing system (Context Diagram) Booking system The whole system

5. External Entity People, programs, organisations, other info systems that provide data to the system or receive output from the system. Nouns are used to name external entities. External entities are things that are external to the system in question. students

6. Context Diagrams The highest level of the data flow diagram. General description of the system and its relationship with “the outside world.” Restaurant System Suppliers Diners Bookings Orders Invoice Payment