Parents up
This page is inspired by rule four in Geert Bellkeens' blog post 5 rules for better UML diagrams.
The elements that are highest in a hierarchy should also be placed highest in a diagram. In other words:
- Subclasses should be placed below their parents.
- In aggregation relationships, the element on "whole-side" should never be below the element on the "part-side".
- For realizations, the original element should be on top.
In the first diagram below, subclasses are placed above their mothers. This makes it difficult to understand the hierarchy in the diagram:
Instead, the subclasses should be aligned below their mother, like in the figure below:
The figure below illustrates an aggregation, with the "whole-side" on top. This is also a hierarchy since DQ_EvaluationMethod is a part of DQ_Element.
