What does the ROM files (FACTORYFS, HIDDEN, CACHE, PARAM, etc.) mean? Flashing my Galaxy S 2 i9100 (after breaking with CyanogenMod update CM-13.x) I used the following command:

sudo heimdall flash \
    --FACTORYFS factoryfs.img \
    --CACHE cache.img \
    --HIDDEN hidden.img \
    --MODEM modem.bin \
    --PARAM param.lfs \
    --BOOT boot.bin \
    --SBL1 Sbl.bin \
    --no-reboot \
    --KERNEL zImage


Question

I'm wondering what's the role of the different files?

update: I encourage you to use CM-12.1 instead of CM-13 for your i9100 as the later is not officially supported.
From [INFO] What the ROM files mean


  boot.bin This is the Primitive Bootloader. Seems to make some basic
  initializations and finally loads the secondary bootloader.
  
  Sbl.bin The Secondary Bootloader. It loads the PIT, the Linux kernel,
  params.lfs and the modem. It also is responsible when the device is
  charging while it's off. This file contains the picture you see when
  in Download-mode. So it's also responsible for the flashing stuff and
  getting into recovery.
  
  The Sbl.bin seems to be there twice. The second one may be for backup,
  if something bad's going on.
  
  param.lfs A collection of JPEGs. These include the Galaxy S-Logo you
  see first when booting the phone as well as the phone-!-computer
  picture, the loading spinner and some pictures of an Android giving
  some information: "CP CRASH UPLOAD MODE", "FORCED UPLOAD by KEY
  PRESSING", "POWER RESET or UNKNOWN UPLOAD MODE", "USER FAULT Not
  KERNEL PANIC UPLOAD MODE" and "KERNEL PANIC UPLOAD MODE". And there is
  the Logo of NTT docomo, which is a Japanese mobile operator company.
  
  Maybe there are more information in this file, but I didn't extract
  it.
  
  The rest of the files should be rather obvious:
  
  zImage is the Linux kernel. 
  
  recovery Backup Kernel. Don't know if it's
  used on every device. 
  
  factoryfs.rfs is the System partition with the
  Android system. 
  
  dbdata.rfs is the partition where the app data get
  stored. 
  
  cache.rfs is for Dalvik cache. 
  
  modem.bin is the Modem.


From How to Use Heimdall – specifically on Samsung Captivate – Download 512 513 and 803 PIT files


  
  IBL+PBL is the boot loader, be extra careful with it;
  PIT is the partition table;
  EFS contains some important data like IEMEI, be extra careful with it;
  SBL is the second boot loader;
  SBL2 is the backup of the second boot loader;
  PARAM contains some images used as various stage of the boot process;
  KERNEL is the kernel;
  RECOVERY is the backup of the kernel;
  FACTORYFS contains /system file system which is some kind of root file system;
  DBDATA contains /data file system which is the database to store application parameters;
  CACHE contains /cache file system which contains the Dalvik cache;
  MODEM contains the firmware for the modem.