XFree86 is the Open Source port of X.Org's X11R6.6 release that supports several UNIX(R) and UNIX-like (such as Linux, the BSDs and Solaris x86) operating systems on Intel and other platforms.
See the Copyright Notice.
The sources for XFree86 are available by anonymous ftp from:
ftp://ftp.XFree86.org/pub/XFree86/4.2.0
Binaries for NetBSD 1.4 and later are available from: ftp://ftp.XFree86.org/pub/XFree86/4.2.0/binaries/NetBSD
A list of mirror sites is provided by http://www.xfree86.org/MIRRORS.shtml
XFree86 also builds on other NetBSD architectures. See section Building on other architectures for details.
XFree86 also supports NetBSD on PC98 machines.