| Term 
 | Definition 
 
        | A set of related classes, usually of relevance to a small subset of the actors. |  | 
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        | Term 
 
        | Point of highest abstraction. |  | Definition 
 
        | The point where input loses the quality of being input and simply becomes internal data operated on by the product. |  | 
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        | Term 
 | Definition 
 
        | Program description language. Basically pseudocode. |  | 
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        | Term 
 
        | Responsibility-driven design |  | Definition 
 
        | A key aspect of object oriented paradigm. If a message is sent to an object, that object is responsible for carrying out any action required. |  | 
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        | Term 
 | Definition 
 
        | Data are considered first. |  | 
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        | Term 
 
        | Operation Oriented Design |  | Definition 
 
        | Emphasis on the operations. |  | 
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