The Leveling Data dialog appears when a Gane & Sarson Data Flow diagram creates a child diagram. The following options are available:
▪Image of parent symbol - a bitmap representation of the parent symbol.
▪Lines/flows attached to parent - all the lines (usually data flows) attached to the parent symbol.
▪Symbols attached to lines/flows - all the symbols attached to those lines.
Here are some tips for creating a leveled Data Flow diagram.
Depending on the complexity of lines and symbols attached to the parent, you may or may not want to include the symbols attached to the lines.
The child diagram can also contain from 5 to 9 process symbols, and the data flows and data stores required to support those processes. Data stores integral to the child diagram should be drawn completely in the parent symbol bitmap; those integral to the system as a whole should be drawn outside the parent symbol.
Input data flows attached to the parent symbol start in space outside the parent symbol bitmap, but must end inside the bitmap attached to a process or data store. Similarly, output data flows must start in a data store or process in the parent bitmap and end in space outside.
In order to balance, all the data going into the parent symbol must go into the child diagram; all the data coming out of the parent symbol must come out of the child diagram.