XFree86 is an Open Source version of the X Window System that supports several UNIX(R) and UNIX-like operating systems (such as Linux, the BSDs and Solaris x86) on Intel and other platforms. This version is compatible with X11R6.6.
See the Copyright Notice.
The sources for XFree86 are available by anonymous ftp from:
Binaries for NetBSD 1.5 and later are available from: ftp://ftp.XFree86.org/pub/XFree86/4.4.0/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.