About This Manual > Operating System References ❏ Microsoft ® Windows ® 8.1 operating system ❏ Microsoft ® Windows ® 8 operating system ❏ Microsoft ® Windows ® 7 operating system Mac OS In this manual, "Mac OS" is used to refer to macOS Catalina, macOS Mojave, macOS High Sierra, macOS Sierra, OS X El Capitan, and OS X Yosemite. 9