I checked out this verdict on Wikipedia, chiefly to see if it is still in use in Scotland. Apparently it is. Despite the negative comments posted at the head of the Wikipedia article, I believe that it is accurate, as far as it goes. Personally, I wish that the verdict were available in other English-speaking jurisdictions.
If you check out the internet by entering "Not Proven" in your browser, you can learn much more about the verdict: for example, that it is still not quite 300 years since it was first in use, and that in Scotland, it is "Not Guilty" that is the newcomer.
One aspect of the verdict that I had long believed was that a Not Proven verdict enabled the accused to be retried if fresh evidence were discovered. Apparently that is a misconception: the legal effect is identical with that of "Not Guilty".
A cynic has suggested that the subtext of a Not Proven verdict is "Not Guilty--but don't do it again".
These musings have arisen because of the farcical trial of Barry Bonds, whose already brilliant baseball career was boosted by steroid use. He was found guilty of obstruction of justice, but the jury was divided on the other charges alleging perjury when he denied having knowingly used steroids. I suggest that Not Proven would have been the ideal verdict, ending the matter. As it is, the disappointed prosecutors may insist on a second trial. I sure hope not: this matter has cost us taxpayers millions of dollars and dragged on too long as it is. IMHO, it is time to let go of this sorry episode.