First, I am new here. If I am not asking something in a helpful way and I should follow a best practice then please advise what format is recommended for this forum. I’ll be happy to oblige.
 sorry, it wasn’t until after i posted and looked back where i saw the best practice right on the same page (wow!). Here we go.
This is a question.
CentOS Linux release 7.6.1810 (Core)
Linux stegr04-L21464 4.20.8-1.el7.elrepo.x86_64 #1 SMP Tue Feb 12 18:03:03 EST 2019 x86_64 x86_64 x86_64 GNU/Linux
 I originally thought that these packages weren’t considered an “old” version that is recommended to be uninstalled according to v18.09 https://docs.docker.com/install/linux/docker-ce/centos/. I think it was because I saw “ce” after 17.05.0 in the packages installed on my system. Now I can’t find anything newer than docker-engine-17.05 & docker-engine-selinux-17.05 so I guess that is when docker-ce became the new and docker-engine/docker-engine-selinux became the old.
I was looking for a version docker-engine-17.09 (because i wanted to build something that required it) and thought I had found docker-engine-17.12. At the time I wondered where I could find its corresponding docker-engine-selinux package that would be compatible (or if docker-engine-selinux-17.05 would be compatible) with docker-engine-17.12. This question is flawed because docker-engine-17.12 doesn’t exist. docker-ce-17.12 does exist. Sorry… will try to close now.
I’ve also found that searching for things on docs.docker.com finds a lot of useful information - including items on this forum. I am interested in what happened to the things that used to be in docker-engine-selinux (did things drastically change or is it all in one docker-ce package). But I’ll see what I can find on over at docker docs.