4.2 Identifying associations
In practice, the identification of associations often proceeds in parallel with the identification of classes. When you are considering a possible class, it is also natural to think about the connections that the entities it represents might have with other entities in the system domain.
However, as with classes, textual analysis can also help to identify associations. Just as nouns and noun phrases can suggest candidate classes, so the grammatical structures that connect these nouns and noun phrases in the text of a requirements document can suggest likely associations. As an example, here again is the requirements document for the DVD Library System. We have started our search for suitable associations by first highlighting the nouns and noun phrases that correspond to the conceptual classes which have already been identified (by showing them in bold italic font), and we have then underlined any grammatical structures that connect these classes.