%n to -n should be more flexible
%n should support something like this:
%2n -> ' 1', ' 2', ..., '10', '11' (always 2 in width)
%02n -> '01', '02', ..., '10', '11' (always 2 in width, pad with zeros)
%-2n -> '1 ', '2 ', ..., '10,, '11' (always 2 in width, align left)
I feel that %0xN is most important of the three.