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.
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.