U     Unsatisfactory: U indicates unsatisfactory achievement (equivalent to C or
       below)on a course taken on a satisfactory/unsatisfactory basis.

I      Incomplete: I must be used only as a prefix to a grade. Assigning
       an incomplete to a student in a course taken for graduate credit
       indicates that, for a valid reason, the course has not been completed and
       that the instructor reserves the right to raise the grade if the incomplete
       work is finalized within one year or by an earlier date specified by the
       instructor.  The grade to which I is prefixed is not used in computing the
       student's grade-point average until the prefix is removed and indicates the
       grade earned if no further work is performed. It is the grade in the course
       unless and until changed by the instructor.