Operational monitoring. Once deployed, ongoing monitoring against established measures is vital to ensure that the system remains both effective and acceptable. If results in real-world operations suggest that, due either to changes in the external environment or to a lack of fidelity in the OT&E environment, system performance does not meet the established thresholds, an immediate agency-level review should be conducted to determine whether operational authorization should be revoked.
Systems evolution. In general, information systems evolve or become obsolete. They evolve for many reasons. For example, new technologies may become available whose adoption can make the system more usable, or new applications may be required in a new operating environment, or new capabilities previously planned but not yet incorporated may be deployed. Because system evolution results in new functionality, reapplication of the framework described in Chapter 2 is usually warranted.