Example A: New IRS data must be used in the payroll system as soon as possible
Example B: Sometime next year, our largest customer willrequire a security code for all online transac tions
Starting next week, the marketing system must track all repeat visits to the Web site.
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Examples of various types of constraints. The constraint in Example A is present, external, and
mandatory. The constraint in Example B is future, external, and mandatory. The constraint in Example C is
present, internal, and desirable. The constraint in Example D is present, internal, and mandatory. The constraint
in Example E is future, internal, and desirable.