A programme of tests that are intended to show that the sterilizer's performance is continually satisfactory. The appropriate tests should be carried out at daily, weekly, and annual intervals. A suitably trained person (usually the individual that operates the sterilizer on a daily basis) should draw up a schedule for periodic testing. After appropriate training the user should perform the daily tests. Many modern sterilizers have an integrated automated test facility that enables the sterilizer to perform some of the specialized weekly tests itself. The user can undertake these after appropriate training. Older sterilizers may require the services of a suitably qualified person to undertake weekly tests. A suitably qualified person should perform annual tests. Each cycle available to the user should be tested. If the sterilizer is not tested periodically it will not be possible to know if it is working correctly. Failure of a test implies that the sterilizer is not working to specification. The user should have a written procedure for handling test failures but, in all cases, the sterilizer must be withdrawn from service, the failure investigated, the cause rectified, and the sterilizer re-tested successfully before being used. The user has the ultimate responsibility for certifying that the sterilizer is fit for use. Sterilization cannot be confirmed by inspection and testing of the product.