Alan Erskine wrote:

Raket (Rocket)?


I think that's it...Chelomei's designs had UR prefixes for "Universal
Rocket" and the ex-German Peenemunde design bureau used G for Groettrup-
its leader....here's some data about the designations in detail:
http://www.astronautix.com/articles/rustions.htm
As one would expect from the Soviets, it's complex and convoluted.

Pat