S2FR is a Lux I red.
S=51-67 lumens
2=613-620nm
F=2.55-2.79 Vf
R=red
ES2R is a very old bin, back when the Vf was first (ca. 2001), but is a Lux I red - the binning document doesn't even mention this old format anymore, but that one would be:
E=2.31-2.55 Vf
S=51-67 lumens
2=613-620nm
R=red