Originally Posted by ruario
untrue, MacOS is UNIX.
OS X 10.8 is UNIX certified....
But none of the more recent releases are. (http://www.opengroup.org/openbrand/register/
If they were, it would properly have said "or later" as shown by the IBM and HP entries.
It is all up to the money. If Apple pays the fees, then the more recent releases would be.
But since they didn't maintain the certification, no, OS X 10.<anything but 8> are not certified UNIX.