The basic rules that apply to DFD development are: • Each context diagram must fit on one page. • The process name in the context diagram should be the name of the information system. • Use unique names within each set of symbols. • Do not cross lines. • Use a unique reference number for each process symbol. In addition to these rules, the systems analyst must use the proper DFD shapes, connect them correctly, and produce a leveled, balanced set of DFDs.

What will be an ideal response?

Three data flow and process combinations must be avoided when creating a DFD:
• Spontaneous generation occurs when a process produces output, but has no input data flow.
• Because it has no input, the process is called a spontaneous generation process.
• A black hole process is a process that has input, but produces no output.
• A gray hole is a process that has at least one input and one output, but the input obviously is insufficient to generate the output shown.