The UAF Operational Sequences viewpoint is a diagram that enables you to view Roles (Performer PerformsInContext Activity) as vertical lifelines, and the OperationalExchanges sent between the Roles as relationship lines between them. This is a UML Sequence type diagram, used for UAF.
The top-to-bottom positioning of the OperationalExchange lines denotes the timing of which OperationalExchange happens first to last (top to bottom).