US Airways Dividend Miles (Pre-FlightFund Merger) - US Fare class lettering?

Ran a few searches and no luck. Does anyone have a list of the USAirways booking class letters and what they refer to (ex: Y=full fare coach, H=mid-fare coach, X=coach standard award, etc.)? I'm specifically looking for R and E.

Thanks

R is Envoy upgrades
E is Domestic FC upgrades for non-premium fares
P is Domestic FC upgrades for premium (Y/B/N/U) fares

R is Envoy upgrades
E is Domestic FC upgrades for non-premium fares
P is Domestic FC upgrades for premium (Y/B/N/U) fares
Thanks neighbor!

Is there a difference in lettering between upgrading a full Y fare to Envoy vs. a discount coach fare like H to Envoy?

Nope. All Envoy is R, no matter what fare class.

-JC