For example, prisons are required to maintain a registry of all detainees, listing, inter alia, the date of, and reason for, incarceration and on whose authority the detainee is being incarcerated. The monitoring process can determine whether this has been done by reviewing the registry and cross tabulating it against information gathered from detainees during the visit. If, for instance, the institution finds a detainee in the prison not listed in the registry, a serious breach has occurred.