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One might argue in favor of using reusable expressions or attributes. Arguments to use one or the other are enumerated below.
- When the expression is clearly only applicable for one entity, an attribute is favored.
- When the expression is used in more entity, a reusable expression is favored. However, attributes that use this expression can still be modeled.
- Remember that not all attributes make sense semantically. The number of persons as an attribute for person makes no sense. If that fact is necessary, perhaps model it as a reusable expression.
- There are arguments to use control-entities or steering-entities. For example to store the number of persons, as mentioned in the previous item. However, they do not have any semantic advantage.
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