No crossings
This page is inspired by rule two in Geert Bellkeens' blog post 5 rules for better UML diagrams.
Diagrams with crossing lines are difficult to read. Therefore, no lines in a diagram should cross each other. If this is not possible, try splitting the diagram into several smaller diagrams, and also evaluate if all relationships are correct and have to be viewed in the current diagram. Remember that each diagram shall focus on a few elements, and have a defined perspective.
In the first figure below, there are several mistakes: crossing lines, and the unnecessary element DQ_Element. The purpose of the figure is to show evaluation methods, and the relation to DQ_Element is not relevant for this purpose. By removing DQ_Element and moving DQ_AggregationDerivation up, we get a tidy and more readable diagram
Wrong:
Correct:
