摘要：A formal model for data flow diagram (DFD) rules is developed by introducing a syntax and semantics for its rules. DFD has been chosen because it is an approach for specifying, constructing and visualizing the model of a system graphically and has been in practical use on a very wide basis but still lacks formal and precise understanding. This formal model can be used to check the correctness of the diagrams and consistency among the diagrams.
关键词：Context diagram; data flow diagram; formal method; consistency rules
