In many diagramming applications, it is essential that a drawing can be labeled.
Labels are visual descriptions, such as text or icons, that are assigned to nodes and edges.
Just as diagram formatting is a time consuming and monotonous task, so is the positioning of labels. Thus, the Graph Layout Toolkit includes algorithms for the automatic placement of edge labels. A label, which is associated with exactly one edge, must not overlap any other edge or any node. Otherwise, it is not clear which object the label describes. Relationships between edges and labels should be easily identified without cluttering the drawing.