switch (FEAT_TRAINS,SELF, switch_rail_freight_vehid_back_layers, [
  STORE_TEMP((getbits(extra_callback_info1, 8, 8) < 4 ? CB_FLAG_MORE_SPRITES  : 0) + PALETTE_USE_DEFAULT, 0x100),
  getbits(extra_callback_info1, 8, 8)
  ]){
  0: sprite_attach_background_8_rail_freight_wagon;
  1: switch_rail_freight_vehid_back_drawing_engine;
  return sprite_attach_foreground_8_rail_freight_wagon;
}