For example, Diabetes references may be assigned to one of seven Level 3 categories: Glutamic Acid Decarboxylase, Heat Shock Proteins, Insulinoma-Associated Protein-2, Islet-Specific Glucose-6-Phosphatase Catalytic Subunit-Related Protein, Insulin/Proinsulin, Other, or Various/Multiple for abstracts that refer to several Diabetes categories. Here, INS is linked to diabetes mellitus.