The variety and diversity of equipment and systems makes it difficult to define general criteria for the evaluation of the effects of interference on electronic products. Nevertheless, the test result must be classified on the basic of operating conditions.

It is important for the manufacturer to specify the limits which define 'degradation or loss of function' an decide which of these criteria should be applied to each test.

The Generic Immunity standard contains a set of guidelines for the criteria against which the operation of the EUT can be judged and which are used to formulate the appropriate criteria for a given EUT against specific tests.

Performance Criteria A : The apparatus shall continue to operate as intended. No degradation of performance or loss of function is allowed below a performance level specified by the manufacturer, when the apparatus is used as intended. In some cases the performance level may be replaced by a permissible loss of performance. If the minimum performance level or the permissible performance loss is not specified by the manufacturer, either of these may be derived from the product description and documentation and what the user may reasonably expect from the apparatus if used as intended.

This performance criteria is generally applied during RF disturbance, like radiated field and RF conducted disturbance.

Performance Criteria B : The apparatus shall continue to operate as intended after the test. No degradation of performance or loss of function is allowed below a performance level specified by the manufacturer, when the apparatus is used as intended. In some cases the performance level may be replaced by a permissible loss of performance. During the test, degradation of performance is however allowed. No change of actual operating state or stored data is allowed. If the minimum performance level of the permissible performance loss is not specified by the manufacturer then either of these may be derived from the product apparatus if used as intended.

This performance criteria is generally applied during transient phenomena, like ESD and burst.

Performance Criteria C : Temporary loss of function is allowed, provided the function is self recoverable or can be restored by the operation of the controls.

This performance criteria is generally applied during dips or voltage variations on mains.