Comment by mwcampbell

It looks like your "Digit grouping symbol" field is empty. I'm sure that's standard in some locales, though not for US English. I don't know how to make that field empty; when I try, Windows says it's invalid. So I wonder if your locale sets that separator to some kind of Unicode character that, in a proper renderer, is equivalent to no character at all. If that's the case, then I'm guessing refterm could handle that character as easily as it handles VT escape codes. But this does lend some weight to the position that Casey was oversimplifying things a bit.