Analyzing Current Systems › Summary of Current Systems Analysis Guidelines › Guidelines for Data Flow Diagrams

Guidelines for Data Flow Diagrams

• The subject and activity parts of a Data Flow Diagram should appear in the procedure hierarchy of a current system activity model.
• The subject of a Current System Data Flow Diagram may be:
  • Collection of current systems relevant to a business area
  • Single current system relevant to a business area
  • Subsystem of a current system
• The activities depicted in a Current System Data Flow Diagram may be:
  • Current system
  • Subsystem of a current system
  • Current system procedure that supports an activity of interest to the business
• A data flow may be from:
  • Procedure to Data Store
  • Data Store to Procedure
  • Procedure to Procedure
  • External Object or System to Procedure
  • Procedure to External Object or System
• Lower-level diagrams should be consistent with the higher level ones.
  • A lower-level Data Flow Diagram cannot contain more inputs and outputs than a higher level diagram.
  • A data store that appears on a higher level must also appear on each lower level diagram.