RR will only show if the footprint of your rotation changes. It will show RS if spills over into the next month. It means absolutely nothing beyond that. That function was tied to some previous definition of reroute. They just gave up trying to code the "new" reroute pay, and just left it as a manual pay modifier like every other hacked up change since 2015.

I know most know this, but DBMS is absolutely ancient. I think they turned in on in 1980. There is stuff left over from 6-8 past contracts, like duty period average, which hasn't been in the contract for more than 10 years.