Between September 1953 and Summer 2008, the following numbering system was used: 001-049, Precollege and deficiency courses; 050-099, Nondegree courses (e.g., agriculture short courses); 100-299, Lower-division courses normally scheduled for freshmen and sophomores; 300-499, Upper-division courses normally scheduled for juniors and seniors; 500-599, Dual-level courses that may be scheduled by juniors, seniors and graduate students for graduate credit; 600-699, Graduate-level courses. In certain circumstances, an undergraduate student may take a 600-level course. In Fall 2008, course numbers were converted to five digits, and professional-level course numbers (80000 to 89999) were added.