There is no such designation. Instead, the convention is:
Paroxysmal AF - it comes and goes on its own and never lasts more than a full week.....!
Persistent - It may come and go, but it does much more often and may last more than a full week;
Long-standing persistent - just what you'd think it means....you've largely been in AF, with breaks here and there, for a year or more; and
Permanent - same thing....what you'd imagine it means.

There are lots of variations of Afib that I am learning and experiencing! An Afib episode might only last a few seconds, a few minutes, a few hours, days or nonstop. I've learned via my Pacemaker recorder that I have various lengths of episodes. Not only that but varying rates of heart beats. The aorta sends out an electrical signal for a heartbeat. If the signals are produced too rapidly, they become chaotic bc the aorta becomes a vibration, rather than efficiently pumping blood into the ventricular chamber. My atrial rate has been recorded as high as 640 beats per minute and my ventricular rate high of 240. Obviously, blood doesn't circulate very well at all when it goes way higher. My pacemaker is set at 60 beats per minute but my max healthy heart rate is ONLY 150. Therefore, I am going for an ablation SOON and I am not a medical professional.