Students who must interrupt their studies may, with the approval of their graduate director, register for matriculation continued for a maximum of two consecutive terms. Matriculation continued also is the proper registration when there is no other appropriate registration category for a student. For example, students in many humanities and social sciences who have completed their formal course work and are preparing for examinations but are not registered for research would register for matriculation continued. There is no tuition fee for this registration, although a student fee is charged. This category of registration is not available to postqualifying doctoral students, who are expected to register for research in their fields until they have completed their degrees. Those students who are away from campus but working on their theses or dissertations and in contact with their committees are required to register for a minimum of 1 credit of research per term. Doctoral degree students who are on campus and engaged in research must register for a minimum of 1 credit per term once they have completed 72 credits. Prior to that, they must register for 3 credits per term. Master's degree students who are on campus and engaged in research must register for a minimum of 1 credit per term, for a maximum of three terms.