Looking for documentation on CreatePersistentImg.sh

[GCMartin]

The Ventoy Linux version contains a file "CreatePersistentImg.sh" when the tar file is expanded into the Ventoy folder along with all the other Ventoy needs. In that folder, too, there is a README file.

Can someone steer me to any documentation on what this, "CreatePersistentImg.sh", is? 
And how to use it when creating a Ventoy bootable disk?

The README file give NO clue to what it is nor when it is to be used. The following is the README

Code:

========== Ventoy2Disk.sh ===============

sudo sh Ventoy2Disk.sh { -i | -I | -u } /dev/XXX  XXX is the USB device, for example /dev/sdb.

Ventoy2Disk.sh CMD [ OPTION ] /dev/sdX
  CMD:
    -i  install ventoy to sdX (fail if disk already installed with ventoy)
    -I  force install ventoy to sdX (no matter installed or not)
    -u  update ventoy in sdX
   
  OPTION: (optional)
  -r SIZE_MB  preserve some space at the bottom of the disk (only for install)
  -s          enable secure boot support (default is disabled)
  -g          use GPT partition style, default is MBR style (only for install)
 

========== CreatePersistentImg.sh ===============

sudo sh CreatePersistentImg.sh

sh CreatePersistentImg.sh  [ -s SIZE_IN_MB ] [ -t FSTYPE ] [ -l LABEL ]  for example:

sh CreatePersistentImg.sh                ---->  persistence.img in 1GB size and ext4 filesystem and casper-rw label
sh CreatePersistentImg.sh -l MX-Persist  ---->  persistence.img in 1GB size and ext4 filesystem and MX-Persist label
sh CreatePersistentImg.sh -s 2048        ---->  persistence.img in 2GB size and ext4 filesystem and casper-rw label
sh CreatePersistentImg.sh -s 4096 -t xfs  ---->  persistence.img in 4GB size and xfs  filesystem  (ext2/3/4 xfs are supported)  and casper-rw label

If no documentation exist, could someone show a use case(s) of how this applies to the Ventoy bootable that is created, please?

Thanks in advance