The notified body makes unannounced visits to the manufacturer, the need for and frequency of which are determined on the basis of the control system managed by the body. The criteria for choosing the body include:
1° The results of previous surveillance visits;
2° The follow-up required for the implementation of corrective measures;
3° Special conditions linked to the approval of the system;
4° Significant changes in the organization of the production process, measures or techniques.
Where appropriate, the organisation arranges for tests to be carried out. Visits and tests are the subject of a report submitted to the manufacturer.