The FSG column is the encoding used by G. Landini in his interlinear transcription, version 1.6 (interln16.evt). It is basically the same encoding used by the First Study Group, with some additions that were needed to allow lossless conversion from other alphabets. As Landini explains in the interlinear file itself:
# [...] The Currier version was originally coded in Currier's # alphabet. I translated [the Currier file] to FSG "enhanced" # alphabet using Jacques Guy's BITRANS program and a set of rules # CUR2FSG2 based on a message by Jim Reeds to the Voynich mailing # list. The FSG alphabet does not contain the Currier characters 6 # and 7. To preserve these, characters 6 and 7 were kept unchanged # in the resulting FSG version. Currier 6 usually corresponds to K # in FSG, while 7 was transcribed as K or 8 by the FSG team.