You will never actually see the code for termination, unless someone sends you a picture. You will have been walked off, long before.
Lots of centers probably don't even post a termination code, because after being code 28 (suspended) for months, then off the schedule entirely, it is obvious what happened.
Code 16, from what I understand is actually "Cleared". It means they gave notice, and left on good terms. But, since management can't talk about employee status, and suspicions and rumors are king at UPS, it evolved into the code for termination.
I don't think there is a code for termination.