Whether the UNC system should have a cap on out-of-state enrollment - and where to peg it - has been the subject of much debate over the years.

But if there is to be such a ceiling, at least the system ought to abide by it - which it failed to do after a snafu last fall.

Our inclination is to think that the cap is a good idea, since it performs the desirable function of making sure that most of the seats in UNC institutions are reserved for North Carolina residents.

The state's admirable constellation of public university campuses was built up at great cost and effort, after all, for the primary purpose of providing a first-rate higher education to the children of North Carolinians at a reasonable price. We would begin to water that principle down, obviously, if we were to open the floodgates to students from wherever.

Nonresidents Increase Diversity

On the other hand, there are good and valid justifications for reserving a sliver of the enrollment pie for nonresident applications. Three such reasons come to mind:

- For one thing, attracting young scholars from the other 49 states and from other countries enhances the quality of university life by increasing diversity. The ability to mingle in class and out with students from farflung locations can add a healthy broadening to the lives of North Carolinians whose lives and attitudes might otherwise have been decidedly more provincial.

- Another reason for admitting more out-of-state students is an economic one - which begins to carry even more weight in times of fiscal belt-tightening such as the one we are currently enduring. This year, tuition for nonresidents is pegged at $23,430 - compared with a relatively modest $4,815 for residents. That added revenue can only come in handy.

- Lastly, opening the academic gene pool at our highly regarded university system to greater numbers of applications from outside, as opposed to turning away such a high percentage of them, would have the effect of raising the overall level of academic excellence. The flip side of that, of course, is that overdoing it would turn our system from the University of North Carolina into the University of Everywhere.

Skating Close to the Edge

At this point, the state has settled on an out-of-state limit of 18 percent, which seems about right. Just how close to that edge we've been skating became clear last fall.

During the summer, the legislature had done away with the fiction that allowed the university to count out-of-state athletes as North Carolina residents. That was the right thing to do. As a result, though, the university had to reclassify 38 out-of-state athletes - including basketball players Kendall Marshall and Harrison Barnes - who had already been admitted under the old rule. That put the school a fraction of a percentage point over the cap, resulting in an automatic penalty: a budget cut of $158,225.

Basketball fans may think the violation was well worth the price. And an argument can be made that the legislature should have waived the punishment in this case, since it was the one that changed signals at the last minute. But a cap doesn't mean much if you don't stay under it.