This is the Debian prepackaged version of the GNU diffutils package.
GNU `diff' was written by Mike Haertel, David Hayes, Richard Stallman,
Len Tower, and Paul Eggert.  Wayne Davison designed and implemented
the unified output format. GNU `diff3' was written by Randy Smith.
GNU `sdiff' was written by Thomas Lord.  GNU `cmp' was written by
Torbjorn Granlund and David MacKenzie.

The source for this release was obtained from

ftp://ftp.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz

The manpages were obtained from the FreeBSD-stable sources located at
ftp.cdrom.com.  They appear to have originally been under the Berkeley
copyright notice quoted in cmp.1, and to have been subsequently placed
under the GNU General Public License by FreeBSD.  They appear to have
been written to describe diff-2.6.

The following copyright statement is from the GNU diffutils source
package, and applies to everything except the manpages:

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   On Debian systems, the complete text of the GNU General Public License
   may be found in `/usr/share/common-licenses/GPL'.

   A copy of the GNU General Public License is also available at
   ftp://ftp.gnu.org/pub/gnu/GPL. You may also obtain it by writing to
   the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
   Boston, MA  02111-1307, USA.