A Legend shape identifies colors and styles you have used to group other elements on the diagram. You can use the Legend to assist in distinguishing different elements, connectors or systems on the diagram. For example, the Legend could show that all elements concerned with the management system are shaded in blue, and all outcomes connectors are shown in red. The Legend displays as a key to the diagram, with the filled shape styles first and the lines and connector styles underneath.
You add a Legend to the diagram, then edit it to add Legend elements, which define the colors and styles used in the diagram.
To add a Legend to a diagram, drag the Diagram Legend element from the Common page of the Toolbox onto the diagram (or click on the New Diagram Legend icon () on the UML Elements toolbar, and click on the diagram).
To edit the Legend either double-click on the Legend or Right-click on the Legend and select the Properties context menu option.