Originally Posted by GUWonder

I found it bizarre too but only gave the 'R' booking code serious thought after calling up to get seats changed (to the E+ section).

I called up a few times and they seem to have no clue about why it would show up as 'R' other than to say that such tickets are not eligible for domestic upgrades as a UA elite and that for US Airways operated flights R earns miles. But these are UA operated flights, so I escalated the matter and they are trying to find out since R is quite clearly not listed as earning miles on united.com.