'What does this code do and what is the meaning of "and b, 000Fh" and "and a, 0xFFC3h"

What does this code do and what is the meaning of "and b, 000Fh" and "and a, 0xFFC3h"? I do understand that it does AND operation bit by bit but I can't find the purpose of the code.

org 100h
.data
    a dw 1010110110001011b   
    b dw 1001010101100101b   
    
.code                         
    mov ax, @data
    mov ds, ax
    mov es, ax
                
    and b, 000Fh
    shl b, 2
    and a, 0xFFC3h
    mov ax, b
    xor a, ax     
        
.exit

Solution 1:^[1]

MODX does an excellent job with common pages, and the built-in ACL system will allow you to differentiate access for any number of closed participants groups.

As for the user's personal data, there are two possible ways: create some custom code or use an existing one. Each of these paths will almost certainly extend the current user model and use it for your needs.

Here are a couple of useful links regarding your question:

https://docs.modx.com/current/en/extending-modx/custom-users

https://docs.modx.com/3.x/en/extras/login/login.tutorials/using-custom-fields

https://modx.com/extras/package/classextender