R stands for Round ( while C stands for carré ).
A stands for Automatic.
E For Etanche ( waterproof, which suggests a screw in case back ).
Back to your watch, you know all the love I have for the Futurematic, a very charismatic and representative watch, IMO.
Your ads and catalogs pics enhance its interest in a dramatic way.
Well done, my friend!
Best,
Nicolas.