Think leahbump has it - to do with the nu,ber of credits:
At the start of Session 1999/2000 the University introduced the Ordinary degree in place of the Pass degree. A candidate who is ineligible to progress on the Honours degree may be transferred to the Ordinary degree if 75 or more credits have been achieved at the end of the Certificate stage, or if 180 or more credits have been gained at the end of the Diploma stage. There is no direct entry to the Ordinary Degree - i.e. you cannot register on the 1st year of an Ordinary Degree.
The candidate must accumulate a total of 300 credits, with the pass mark for modules as for the Honours Degree. Some compensation and referal is permitted on the Ordinary Degree, and in some circumstances, a student may, having completed the Ordinary Degree, be permitted to return to complete extra modules to "top-up" to the Honours Degree.