Classification in scientific and technical writing

Classification is the rhetorical device closely related to formal definition. The first step in definition is to classify the term being defined. The term is placed in a group whose members have at least one outstanding characteristic in common. This member is differentiated from all other members of the class. In classification, however, the groups rather than individual members are differentiated. The reader is given the important information about the name of the class, the members of the class important for the discussion and basis for classification, often called criterion of difference. The basis of classification always reflects the particular purpose of the writer making the classification, and the basis relevant to one person may well be irrelevant to another.