The event Flow Diagram is represented by these event flow diagram symbols. These vector symbols aid in the creation of professional-looking diagrams and documentation. The Event Flow Diagram symbols shown below will greatly simplify your drawing. Flowcharts are made up of a few common geometric shapes that represent steps. A rectangle is the most common shape to depict a single action or operation. Unless you have specialized knowledge and are creating a diagram for a peer group with similar knowledge, stick to basic flowchart symbols. If your diagram contains more than the most basic flowchart symbols, including a legend or symbol key is a good idea.