- Bubbles represent diagram elements such as class boxes, object boxes, use cases, and actors.
- Lines represent diagram elements such as associations, dependencies, and transitions between states.
- Labels represent diagram elements such as class names, association roles, and constraints.
Figure 1. Depicting crossing lines.
Figure 2. Improving the attractiveness of a diagram.
Figure 3. Indicating uncertainty on a diagram.
- Avoid Crossing Lines
- Crossing Lines Jump One Another. When you need to have two lines cross one of them should “hop” over the other, using the notation that you see in Figure 1 borrowed from electrical-wiring diagrams.
- Avoid Diagonal or Curved Lines
- Apply Consistently-Sized Bubbles. In the first version of the diagram in Figure 2 the A bubble is larger than the others, drawing attention to it.
- Show Only What You Have To
- Prefer Well-Known Notation Over Esoteric Notation
- Reorganize Large Diagrams Into Several Smaller Ones
- Include Whitespace In Diagrams
- Focus on Content First, Appearance Second
- Cleanup to Rethink a Diagram
- Organize Diagrams Left to Right, Top to Bottom
- Set and Follow Effective Naming Conventions
- Apply Common Domain Terminology in Names
- Only Bring Language Naming Conventions into Design Diagrams
- Indicate Unknowns with a Question Mark. Figure 3 depicts two examples.
- Consider Adding Color to Your Diagrams
Material for this article was summarized from Chapter 2 of The Elements of UML 2.0 Style.