An atypical scenario is something that needs to be accomplished within the system, but only seldom. The actions have to be done correctly, but perhaps at lower efficiency. The customer should hope that an unexpected error condition is an atypical event. Nonetheless, the system should be able to deal with many categories of faults by using several established techniques, such as exception handlers, replications, process monitoring, and roll over. Atypical scenarios and typical scenarios share similar coverage.