I switched the naming of the variables of the frequency filtering to a more clear and easy one.
The change affects the JSON input file and the code itself.
The following renaming is used:
FC_START -> F_LOW_PASS_START
FC_END   -> F_LOW_PASS_END
FC_INCR  -> F_LOW_PASS_INCR
FC_EXT   -> F_LOW_PASS_EXT
FC       -> F_LOW_PASS
F_HP     -> F_HIGH_PASS

However, old JSON files will also work for now. If one of the old variables is not found, IFOS will search for the corresponding old one. This option will be removed in a future release.