In a Niagara R2 station, a particular folder has a very high number of links. The completed links in this folder show tags with "??" instead of the usual letters.
TAC I/A Series
The "??" tag names indicate that the available letter tags have all been used up.
They start at "a" and go to "z" then re-start with "aa" and finish at "zz". If there are additional links, the tags display "??". This is a display only limitation and will not cause any performance issues.