I'm embarrassed to say that I have forgotten something. When I want to
open my flight plan, and I look at the frequencies printed above the
VOR, it says 122.1R 122.4. Does the 'R' refer to what I need to do or
what the Radio operator does? That is, do I send on 122.4 and receive
on 122.1, or the other way around?

I know I can also try 122.2. Under what circumstances do you use one
vs the other?

Tom