This standard should be used when reliability requirements are expressed as a success rate. The specified success rate is the probability that a device performs a certain function or that an action is successful, under the established conditions. The observed success rate can be defined as the relationship between the number of devices or actions without failure at the completion of the test and the total number of devices under test or actions. These plans are based on the hypothesis that each action is statistically independent. The test plans given in this standard are applicable to both reusable and non-reusable devices. Reusable devices, when they are also repairable, can be repaired between successive actions, assuming that the state and operating characteristics are the same as for all of them at the beginning. For non-reusable devices, only one device is used in each performance.