(SRP) The Single Responsibility Principle.
* Each responsibility should be a separate class, because each responsibility is an axis of change.
* A class should have one, and only one, reason to change.
* If a change to the business rules causes a class to change, then a change to the database schema, GUI, report format, or any other segment of the system should not force that class to change.

Related:
* OneResponsibilityRule ''(MergeMe? Merge ORR into SRP?)''
* PrinciplesOfObjectOrientedDesign
* ResponsibilityDrivenDesignConflictsWithYagni

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CategoryModellingLawsAndPrinciples