X11R6.8.0 is an Open Source version of the X Window System that supports many UNIX(R) and UNIX-like operating systems (such as Linux, FreeBSD, NetBSD, OpenBSD and Solaris x86) on Intel and other platforms. Documentation on X11R6.8.0 can be obtained from http://freedesktop.org/~xorg/X11R6.8.0/doc/