Oh, just as opposed to unary. Writing numbers in the ordinary way in any ordinary base, which is to say, bases greater than 1; base 2, base 3, base ten, whatever.
It's worth pointing out that we are talking about representing numbers in unary, though. Or even more directly, plain ol' string length since the RE under discussion doesn't even care what symbols you are using, so "11111" = "abcde" under this RE.
