In short, the product or service must perform as necessary and must be desired.
In conducting value studies we classify functions as either basic
or secondary:
Basic function - 1. That which is essential to the performance of a work or sell function, 2. The function describing the primary utilitarian characteristics of a product or service to fulfill a user requirement.
Secondary function - 1. The manner in which the basic function was implemented, 2. A function indicating quality, dependability, performance, convenience, attractiveness, and general satisfaction beyond that needed to satisfy minimum user needs.
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