Requirements describe the dependability of a system such as service outages and incorrect processing.

Reliability requirements describe the dependability of a system such as service outages and incorrect processing.
in FURPS+ acronym, R stands for reliability in which we check for system failures predictable, accuracy, recoverable etc.
F stands for functionality, u stands for usability, R for reliability, P for performance, S for supportability and Plus for other constraints. Robert Grady of HP devised this FURPS+ acronym.

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Maximizing the difference between total revenue and total cost;