Ubuntu – Kubuntu 18.04: How does Dolphin file manager sort files “naturally”

I have the following files:

$ ls
_010.txt  01.txt    10.txt    1.txt  3.txt  mov001  mov00a  _mov00A  mov00B  mov01A
010.txt   _0mov00A  _1mov00A  2.txt  4.txt  mov002  mov00A  mov00aA  mov010
$ 

I used ls -1 by itself or preceded by various LANG= options and the order of files is as shown below:

ls -1                 |                 
ls -1 LANG=en_GB.utf8 |  ls -1 LANG=C   
ls -1 LANG=en_US.utf8 |  ls -1 LC_ALL=C  
---------------------------------------
       _010.txt       |     01.txt      
       010.txt        |     010.txt     
       01.txt         |     1.txt       
       _0mov00A       |     10.txt      
       10.txt         |     2.txt       
       _1mov00A       |     3.txt       
       1.txt          |     4.txt       
       2.txt          |     _010.txt    
       3.txt          |     _0mov00A    
       4.txt          |     _1mov00A    
       mov001         |     _mov00A     
       mov002         |     mov001      
       mov00a         |     mov002      
       mov00A         |     mov00A      
       _mov00A        |     mov00B      
       mov00aA        |     mov00a      
       mov00B         |     mov00aA     
       mov010         |     mov010      
       mov01A         |     mov01A      

But when I use the Natural sorting option (Dolphin Preferences > General > Sorting Mode) of Dolphin 17.12.3 which is the default version of Kubuntu 18.04, I get a different sorting order as shown in the Name column in the image below:

My question: how does Dolphin achieve this type of sorting?

The Dolphin Handbook doesn't have much to say:

Sorting Mode controls how items are sorted in the view. If Natural
sorting is enabled, the sort order of three example files will be

File1,

File2,

File10.

If this option is disabled, the normal alphabetical sorting case
sensitive or case insensitive will be used, which leads to the sort
order

File1,

File10,

File2.