The evaluation is a generic process designed to verify whether or not a specific service is acceptable. In this context the following basic principles must be taken into account:

• Before the transition of service design or service changes into production these must be evaluated.
• Every variance between the predicted and current performance must be assessed by the customer and finally accepted. If needs be the change may have to be reversed.

Where practicable at reasonable cost, all unintended as well as intended effects of a change should be identified and their consequences for the operation and use of the services understood. The Deming cycle, Plan-Do-Check Act, is used in order to implement the concept so that a consistent and objective verification or evaluation can be carried out