From PoSa:

''The PresentationAbstractionControl architectural pattern (PAC) defines a structure for interactive software systems in the form of a hierarchy of cooperating agents. 

Every agent is responsible for a specific aspect of the application's functionality and consists of three components: presentation, abstraction, and control. 

This subdivision separates the human-computer interaction of the agent from its functional core and its communication with other agents.''

See http://www.idemployee.id.tue.nl/p.markopoulos/downloadablePapers/PhDThesisPanosMarkopoulos.pdf page 27 for further explanation of the PAC pattern, as well as http://en.wikipedia.org/wiki/Presentation-abstraction-control

See also HierarchicalModelViewController

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CategoryAbstraction