Northern Iowa changed its course numbering system from 3 digits to 4 digits at the start of the fall 2011 semester. The University of Northern Iowa offers classes up to 7999. The College of William and Mary uses 5 digits for course reference numbers (CRNs). The CRN's first digit is 2 for a spring class, 3 for a summer class, and 1 for a fall class. Sometimes the same course is taught by different faculty and/or at different times. In this case, a section number is used to differentiate between the different classes. See also Course allocation Course credit References External links Curricula