Figure BBB.3.4.1-1 illustrates a message sequence example for the external verification model in the case where the Machine Parameter Verifier (MPV) detects that one or more machine adjustments are required before authorizing treatment, and the TDS has been configured to retrieve the failure information and make the required adjustments.

The steps in this use case replace Steps 8a to 9f in Use Case BBB.3.2, for the case where only a single beam is delivered.