Use Subject Group Classes in OpenClinica to categorize Subjects within a Study, such as for treatment options. For example, you might create a Subject Group Class called Treatment Group that contains three Subject Groups within the Class: Regimen I, Regimen II, and Regimen III. There can be multiple Group Classes within a Study. For example, you can also have a Group Class for age with these Groups: Adolescent, Adult, and Elderly. You can specify that a Study Subject be required to be assigned to a Group, or allow assignment to Groups as optional. A Study Subject can be assigned to more than one Group Class, but can be assigned to only one Group within a Group Class.