No clue I know the normal code goes off R E P U B L I C A S = 1 2 3 4 5 6 7 8 9 0
Maybe the second R got screwed up and looks like an F? That's all I can figure.
I just asked Litto and he said
REPUBLICAS
0123456789
If it was RP/RS then it would be 02/09 or Feb 2009 Box date.
Some of the factory workers mix it up also. I just got a box with RR/RS, which could only work out to be 11/10. By the codes Litto intended it would be 00/09.I always mix up the R S and 0 1.