Registration

Full-Time Students - Graduate students registered for 9 or more credits, Master's Continuing Research (Grad 900), or Doctoral Research (999) are classified as full-time students. Students holding assistantship appointments are also considered full time and must register for a minimum of 6 credits, Master's Continuing Research (Grad 900), or Doctoral Research (999) each semester.
Three-Quarter-Time Students - Graduate students not on an assistantship and registered for 7 or 8 credits are classified as three-quarter-time students.
Half-Time Students - Graduate students not on an assistantship and registered for 5 or 6 credits are classified as half-time students.
Maximum Load - The maximum graduate load allowed is 16 credits (12 credits for a student on a full assistantship). 

flow chart of course registration
"All Doctoral candidates must register for Doctoral Research (999) each semester after advancement to candidacy until their degree is conferred, even if the minimum requirement (two semesters) has been met."