This regular expression package was originally developed by Henry Spencer.
It bears the following copyright notice:

**********************************************************************

Copyright (c) 1998, 1999 Henry Spencer.  All rights reserved.

Development of this software was funded, in part, by Cray Research Inc.,
UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
Corporation, none of whom are responsible for the results.  The author
thanks all of them. 

Redistribution and use in source and binary forms -- with or without
modification -- are permitted for any purpose, provided that
redistributions in source form retain this entire copyright notice and
indicate the origin and nature of any modifications.

I'd appreciate being given credit for this package in the documentation
of software which uses it, but that is not a requirement.

THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

**********************************************************************

PostgreSQL adopted the code out of Tcl 8.4.1.  Portions of regc_locale.c
and re_syntax.n were developed by Tcl developers other than Henry; these
files bear the Tcl copyright and license notice:

**********************************************************************

This software is copyrighted by the Regents of the University of
California, Sun Microsystems, Inc., Scriptics Corporation, ActiveState
Corporation and other parties.  The following terms apply to all files
associated with the software unless explicitly disclaimed in
individual files.

The authors hereby grant permission to use, copy, modify, distribute,
and license this software and its documentation for any purpose, provided
that existing copyright notices are retained in all copies and that this
notice is included verbatim in any distributions. No written agreement,
license, or royalty fee is required for any of the authorized uses.
Modifications to this software may be copyrighted by their authors
and need not follow the licensing terms described here, provided that
the new terms are clearly indicated on the first page of each file where
they apply.

IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY
FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY
DERIVATIVES THEREOF, EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT.  THIS SOFTWARE
IS PROVIDED ON AN "AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE
NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
MODIFICATIONS.

GOVERNMENT USE: If you are acquiring this software on behalf of the
U.S. government, the Government shall have only "Restricted Rights"
in the software and related documentation as defined in the Federal 
Acquisition Regulations (FARs) in Clause 52.227.19 (c) (2).  If you
are acquiring the software on behalf of the Department of Defense, the
software shall be classified as "Commercial Computer Software" and the
Government shall have only "Restricted Rights" as defined in Clause
252.227-7013 (c) (1) of DFARs.  Notwithstanding the foregoing, the
authors grant the U.S. Government and others acting in its behalf
permission to use and distribute the software in accordance with the
terms specified in this license. 

**********************************************************************

Subsequent modifications to the code by the PostgreSQL project follow
the same license terms as the rest of PostgreSQL.
(License follows)
****************************************************************************
PostgreSQL Database Management System
(formerly known as Postgres, then as Postgres95)

Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group

Portions Copyright (c) 1994, The Regents of the University of California

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose, without fee, and without a written agreement
is hereby granted, provided that the above copyright notice and this
paragraph and the following two paragraphs appear in all copies.

IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO
PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
****************************************************************************
And if that's not enough, changes made from wxWindows are put under the 
wxWindows license:
****************************************************************************
                wxWindows Library Licence, Version 3
                ====================================

  Copyright (C) 1998 Julian Smart, Robert Roebling [, ...]

  Everyone is permitted to copy and distribute verbatim copies
  of this licence document, but changing it is not allowed.

                       WXWINDOWS LIBRARY LICENCE
     TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
  
  This library is free software; you can redistribute it and/or modify it
  under the terms of the GNU Library General Public Licence as published by
  the Free Software Foundation; either version 2 of the Licence, or (at
  your option) any later version.
  
  This library 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 Library
  General Public Licence for more details.

  You should have received a copy of the GNU Library General Public Licence
  along with this software, usually in a file named COPYING.LIB.  If not,
  write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  Boston, MA 02111-1307 USA.

  EXCEPTION NOTICE

  1. As a special exception, the copyright holders of this library give
  permission for additional uses of the text contained in this release of
  the library as licenced under the wxWindows Library Licence, applying
  either version 3 of the Licence, or (at your option) any later version of
  the Licence as published by the copyright holders of version 3 of the
  Licence document.

  2. The exception is that you may use, copy, link, modify and distribute
  under the user's own terms, binary object code versions of works based
  on the Library.

  3. If you copy code from files distributed under the terms of the GNU
  General Public Licence or the GNU Library General Public Licence into a
  copy of this library, as this licence permits, the exception does not
  apply to the code that you add in this way.  To avoid misleading anyone as
  to the status of such modified files, you must delete this exception
  notice from such code and/or adjust the licensing conditions notice
  accordingly.

  4. If you write modifications of your own for this library, it is your
  choice whether to permit this exception to apply to your modifications. 
  If you do not wish that, you must delete the exception notice from such
  code and/or adjust the licensing conditions notice accordingly.
****************************************************************************