Hotrod,
From the Levine site,
"Knife about 4-1/2 inches in overall length which, when
folded, was clearly designed for carrying in a pocket or
purse, was an 'ordinary pocketknife' as defined by this
section." (1989)
I've tried to find a write up on that particular case so I could understand the specifics of it, but, not being an attorney, I'm having a little difficulty. I do remember that just a few years ago there was some language floating around that quoted 3" (I don't recall whether that was for folded or blade length). I'm very puzzled at the 4.5" thing above which I only noticed in the last 6 months or so. The actual statute itself, as you can see on that website, is very vague as to what an "ordinary pocketknife" would be. Clearly it seems that this has been discussed on more than one occassion during trials and opinions have been rendered into case law.
A few people to which I've spoken, including LEO's, have indicated to me that if it folds it's a pocket knife. On the other hand, I've heard conflicts with this opinion as well.
I essentially have come to the personal conclusion that it's apparently an issue up for some debate so I'll carry according to my likely needs of the day, try to stay out of trouble, don't act suspicious, and not worry about it. I typically only spend effort being concious of blade length when I'm spending a lot of time in federal, state, or county buildings. I come from a rural background where no one gave any real thought to your knife or gun carry (they were simply viewed tools like any other in the shed, to be used appropriately). I still have a great deal of difficulty adjusting to the new "improved", more populace, and more PC North Carolina as opposed to the North Carolina of my youth. I understand this problem is common across most of our great nation.