Info about more than 16 partitions

I noticed a few years ago that some distros would allow more than 16 partitions to be created with no extended partition needed. This is great.
In the past, only 16 partitions were allowed per disk.

My latest MX Distro, has this too.

My questions is:

Exactly what drivers/daemons/software is involved in allowing this ?
I cannot find any info googling the subject.

I need to know this in order that I can always activate this on my servers.
It is nice for where you need a lot of small partitions to manage.
I currently have a drive setup with about 22 partitions.
It is a life saver and saves me the extra drives.

Limits goes away when you use GPT instead of MBR. 4 primary partitions is a restriction of the MBR partition layout and not directly Linux thingy.

I forgot that these were GPT formatted.
That makes sense.

Thanks a lot, I should have figured this out myself.