Question About Minstall User Account Directories

Hi
I'm new here, but have been a lurker for quite some time. The lowend family are easily my go to websites for everything regarding VPS's. I have setup a few LEMP setups on different VPS's by hand, and have always done it the Debian way with sites-available and sites-enabled directories. For my new VPS I opted to go with a bootstrap script to get things up and running, and decided to go with maxexcloo's Minstall bash scripts. Everything worked perfectly, and his scripts were able to get a system up and running for me in no time flat.
I was pretty surprised to see the conf.d setup in /etc at first, but in about 10 minutes I felt right at home with it. It's really not that much different from the old way I had been using. My question, as the title of this thread implies, is about the directories Minstall sets up on each user account within the http folder.
I had figured out pretty quickly that hosts is where the document roots for my vhosts go, and I figured out that logs are where the log files go. It wasn't immediately obvious what the private folder was for, but then I noticed in php-fpm's setup that the socket file goes there. My question is regarding the purpose of the "common" directory. Being someone who likes to scratch my own itch I dug through the source code of the Git Hub project trying to find out what it's used for. I was able to find the snippet of bash code where the four directories are created in manage-common.sh. Figuring I had probably missed something I decided I would dig further through the source of the entire project on my local system using grep. I was not able to turn up what the purpose of the directory is for. Does anyone here know what purpose it serves?
Thanks in advance...