Systems Event/Trace Descriptions, sometimes called Sequence Diagrams, Event Scenarios, and Timing Diagrams, allow the tracing of actions in a scenario or critical sequence of events. Systems Event/Trace Descriptions can be used by themselves or in conjunction with Systems State Transition Descriptions to describe dynamic behavior. The Systems Event/Trace Descriptions in the systems architecture view may reflect system-specific aspects or refinements of critical sequences of events described in the operational architecture view.

The Event/Trace Description is captured using the System Event/Trace Diagram, which shows interactions in terms of messages, or information transfers, between system nodes arranged in time sequence.

The Event/Trace diagram shows the system nodes involved in the scenario by vertical dashed lines, called Sys Node Event Timelines. Horizontal line symbols between the Sys Node Event Timelines represent the messages, or System Events, passed between the system nodes. The System Events are drawn chronologically from the top of the diagram to the bottom; the horizontal placing or spacing of objects is arbitrary.