This is a little diagram I put together years ago when macOS El Capitan came
out and I ran into issues with how it was impacting my
variable. It ends up that every so often I need to reference it.
Today was one of those days. However, I couldn't remember where I put it. The first place I looked was my blog. But it wasn't there. Therefore once I found it it I decided it was finally time to put it up on my blog. I hope it ends up being as useful for you as it has been for me over the years.
Note: This diagram was built with a tool that I very much enjoy using when it makes sense, Monodraw.