Origin of the name “OpenServer” for the SCO Unix operating system

Question

I was looking over the evolutionary history of Unix and Unix-like systems on Wikipedia and one operating system name stood out to me: OpenServer.

Judging from the image, SCO's OpenServer is completely closed sourced; so why does SCO OpenServer have the word "open" in its name if the operating system is proprietary and contains no open source code?

I suspect this is because the original Unics operating system had a mixed/shared license, but that seems like a pretty distant ancestor when the proprietary Xenix came before OpenServer as well. Can anyone shed some light on the reason for this name?