Any other kind of maintenance testing apart from periodic, scheduled, fixed-interval testing is referred to as demand tests.

• Includes periodic tests. Other tests are required only when trouble occurs.

• Can be run by the system when the system detects a need or can be run by maintenance personnel in troubleshooting activities.

• Using the management terminal, maintenance personnel can demand the same tests that the system initiates in periodic or background testing.

• Some non-periodic demand tests are destructive (service-disrupting) tests, and are identified in boldface type.