CFF Subrs subsetting Unreferenced subroutines are nullified (not removed) in a subset font Separate Interpreter struct from hb-ot-cff-common-private.hh in a set of four header files, augmented for CharString (CS): hb-cff-interp-common-private.hh hb-cff-interp-dict-common-private.hh hb-cff-interp-cs-common-private.hh hb-cff-interp-cs.hh Interpreter runtime is separated off as a new struct InterpEnv sub-classed differently for Dict and CharString (CS)