I'm working on a Linux server.
Without the -2 '--nn', the command (below) ran correctly, just the labels in the reformatted volume had weird boundaries because of the wrong interpolation method. 
"$MUNGERDIR/munger" -b "$REGBINDIR" -i -a -w -r 0102 -T 22 -l af -X 16 -C 4 -G 32 -R 3 -A '--exploration 16 --accuracy 0.8 --class-ref label --class-flt label' -W '--accuracy 0.8 --energy-weight 5e-1 --class-ref label --class-flt label' -s refbrain/"${REFBRAIN}" images