Two recent Apple KB articles of note: 106605: Mac OS X 10.1: Do Not Reinstall After Using the Mac OS X Update 10.1.1 states: "You should not reinstall Mac OS X 10.1 ...
If you rely on your Mac and don’t want to upgrade to a newly released operating system, you may want to opt out of the automatic download that Apple is starting to push for macOS Sierra. If your Mac ...