In fairness, I should've contracted even further to the ISO 3166 code "RU"

Vehicle codes are only slightly less clear than the ISO codes, but they're used in a surprising number of places, like international sports.

Edit: Oh wait, I'm mis-speaking. Sports tend to use https://en.wikipedia.org/wiki/ISO_3166-1_alpha-3, which includes RUS

So yeah, I guess I don't feel bad.