There are 13 boxes (17 if you include sub-types) in Figure 2-7. That is a typical number for a subject area model, and is acceptable at the end of a chapter to let people understand how the subject area fits together. However…

Under no circumstances should a subject area try to squeeze more than 15 (maximum 20, but only if it is otherwise aesthetically perfect) boxes into the space of an A4[(] piece of paper. If you get close to that number, you probably have two (or more?) subject areas, and these should be in separate drawings.

In addition, the model should not be presented as a single drawing. Begin with a drawing that has between one and three entity classes and their relationships. Highlight those entity ...

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