Here is how I understand your codes and what they mean:
It means you are wanting to board a train at an intermediate stop, not either end (that's what RL signifies).
You were originally wait list #2 (WL2) for a confirmed berth (CNF). A confirmed birth is basically a single person bed/bench/bunk. You are RAC, which means you can board the train, but are only going to get a single seat on a bench, which will be shared (the bench) with another person (that's what RAC is). The number 4 (RAC4) signifies your place in the queue to get a CNF. If your code counted down from RAC4, to RAC3, RAC2, RAC1, and finally to show CNF, you would then be confirmed for that coveted single person berth.
As I understand the system, and almost no one does, you actually started out (although maybe you never noticed) at WL2, then someone ahead of you cancelled their reservation and you went to WL1. (WL's are wait list codes, in other words you cannot board the train, but are wait listed for someone else to cancel). Then when a second person cancelled their reservation, your ticket went from WL1 to RAC4, which is good in that you can board, but bad because you have to share your bench and it's a long long LOOOONG trip.
So, now you are hoping that 4 more people cancel, so that you can get a CNF!
This is the single most confusing scheme I've ever heard of, by the way.