Building on Pádraig's Gnulib patches of November, I installed the 
attached to add support to Coreutils for the new SI prefixes R and Q.

It'll be a while before 'df -h' outputs them, as I'm not expecting file 
systems in the ronnabyte range soon, given that the total amount of data 
storage in the world is still less than a yottabyte, and given that 
we'll need 128-bit integers support all this consistently. Still, the 
new R and Q prefixes are supported by 'sort' and 'numfmt' as-is.