Z:gnu-www-ja-sco-gnu-linux--848217-Unix is a complete operating s/en

Unix is a complete operating system, but Linux is just part of one. SCO is using the popular confusion between Linux and the GNU/Linux system to magnify the fear that it can spread. GNU/Linux is the GNU operating system running with Linux as the kernel. The kernel is the part of the system that allocates the machine's resources to the other programs you run. That part is Linux.