I come from a university where the first two digits of your student number represents when you started in the university. As such people often use this to judge age, whether the person is repeating or changed course, or is an incoming postgraduate. Student numbers are the identifier for students, and are consequently used in all official capacities, but also in terms of clubs and societies. Attempting to join a club without the right two digits can often be difficult; generally lower digits are a serious social no-no. A student number can never be changed, under any circumstances. If someone starts a course with a hiatus of twenty years, they will still be using their original number. There is also the issue of semi-anonymized information being easy to identify if results are given out using people’s student numbers (if someone doesn’t have the same first two digits as the rest of his peers).
Naturally a unique identifier is a positive thing for managing information. Also having consistency in relation to the manner in which information is recorded is also good. So what sort of action could be performed at the level of the institution to remove this bizarre social stigma, and increase campus social integration, without potentially damaging the integrity in the way in which information is managed (and incurring additional costs of implementation).