Chapters:
1: Introduction
2: Simple example
3: Invocation
4: Finer Control
5: X-Y Plots
6: Contour Plots
7: Image Plots
8: Examples
9: Gri Commands
10: Programming
11: Environment
12: Emacs Mode
13: History
14: Installation
15: Gri Bugs
16: Test Suite
17: Gri in Press
18: Acknowledgments
19: License
Indices:
Concepts
Commands
Variables

# 19: License

Gri is distributed under the GPL public license, an Open Source license that provides certain rights and freedom to users, notably the access to source code and the right to modify it and/or redistribute it. The full text of the GPL license is given below.

    		    GNU GENERAL PUBLIC LICENSE
    		       Version 2, June 1991

     Copyright (C) 1989, 1991 Free Software
         Foundation, Inc.  59 Temple Place, Suite
         330, Boston, MA 02111-1307 USA

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

    			    Preamble

      The licenses for most software are designed to
    take away your freedom to share and change it.
    By contrast, the GNU General Public License is
    intended to guarantee your freedom to share and
    change free software--to make sure the software
    is free for all its users.  This General Public
    License applies to most of the Free Software
    Foundation's software and to any other program
    whose authors commit to using it.  (Some other
    Free Software Foundation software is covered by
    the GNU Library General Public License instead.)
    You can apply it to your programs, too.

      When we speak of free software, we are
    referring to freedom, not price.  Our General
    Public Licenses are designed to make sure that
    you have the freedom to distribute copies of free
    software (and charge for this service if you
    wish), that you receive source code or can get it
    if you want it, that you can change the software
    or use pieces of it in new free programs; and
    that you know you can do these things.

      To protect your rights, we need to make
    restrictions that forbid anyone to deny you these
    rights or to ask you to surrender the rights.
    These restrictions translate to certain
    responsibilities for you if you distribute copies
    of the software, or if you modify it.

      For example, if you distribute copies of such a
    program, whether gratis or for a fee, you must
    give the recipients all the rights that you have.
    You must make sure that they, too, receive or can
    get the source code.  And you must show them
    these terms so they know their rights.

      We protect your rights with two steps: (1)
    copyright the software, and (2) offer you this
    license which gives you legal permission to copy,
    distribute and/or modify the software.

      Also, for each author's protection and ours, we
    want to make certain that everyone understands
    that there is no warranty for this free software.
    If the software is modified by someone else and
    passed on, we want its recipients to know that
    what they have is not the original, so that any
    problems introduced by others will not reflect on
    the original authors' reputations.

      Finally, any free program is threatened
    constantly by software patents.  We wish to avoid
    the danger that redistributors of a free program
    will individually obtain patent licenses, in
    effect making the program proprietary.  To
    prevent this, we have made it clear that any
    patent must be licensed for everyone's free use
    or not licensed at all.

      The precise terms and conditions for copying,
    distribution and modification follow.

    		    GNU GENERAL PUBLIC LICENSE

       TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION
       AND MODIFICATION

      0. This License applies to any program or other
    work which contains a notice placed by the
    copyright holder saying it may be distributed
    under the terms of this General Public License.
    The "Program", below, refers to any such program
    or work, and a "work based on the Program" means
    either the Program or any derivative work under
    copyright law: that is to say, a work containing
    the Program or a portion of it, either verbatim
    or with modifications and/or translated into
    another language.  (Hereinafter, translation is
    included without limitation in the term
    "modification".)  Each licensee is addressed as
    "you".

    Activities other than copying, distribution and
    modification are not covered by this License;
    they are outside its scope.  The act of running
    the Program is not restricted, and the output
    from the Program is covered only if its contents
    constitute a work based on the Program
    (independent of having been made by running the
    Program).  Whether that is true depends on what
    the Program does.

      1. You may copy and distribute verbatim copies
    of the Program's source code as you receive it,
    in any medium, provided that you conspicuously
    and appropriately publish on each copy an
    appropriate copyright notice and disclaimer of
    warranty; keep intact all the notices that refer
    to this License and to the absence of any
    warranty; and give any other recipients of the
    Program a copy of this License along with the
    Program.

    You may charge a fee for the physical act of
    transferring a copy, and you may at your option
    offer warranty protection in exchange for a fee.

      2. You may modify your copy or copies of the
    Program or any portion of it, thus forming a work
    based on the Program, and copy and distribute
    such modifications or work under the terms of
    Section 1 above, provided that you also meet all
    of these conditions:

        a) You must cause the modified files to carry
        prominent notices stating that you changed
        the files and the date of any change.

        b) You must cause any work that you
        distribute or publish, that in whole or in
        part contains or is derived from the Program
        or any part thereof, to be licensed as a
        whole at no charge to all third parties under
        the terms of this License.

        c) If the modified program normally reads
        commands interactively when run, you must
        cause it, when started running for such
        interactive use in the most ordinary way, to
        print or display an announcement including an
        appropriate copyright notice and a notice
        that there is no warranty (or else, saying
        that you provide a warranty) and that users
        may redistribute the program under these
        conditions, and telling the user how to view
        a copy of this License.  (Exception: if the
        Program itself is interactive but does not
        normally print such an announcement, your
        work based on the Program is not required to
        print an announcement.)

    These requirements apply to the modified work as
    a whole.  If identifiable sections of that work
    are not derived from the Program, and can be
    reasonably considered independent and separate
    works in themselves, then this License, and its
    terms, do not apply to those sections when you
    distribute them as separate works.  But when you
    distribute the same sections as part of a whole
    which is a work based on the Program, the
    distribution of the whole must be on the terms of
    this License, whose permissions for other
    licensees extend to the entire whole, and thus to
    each and every part regardless of who wrote it.

    Thus, it is not the intent of this section to
    claim rights or contest your rights to work
    written entirely by you; rather, the intent is to
    exercise the right to control the distribution of
    derivative or collective works based on the
    Program.

    In addition, mere aggregation of another work not
    based on the Program with the Program (or with a
    work based on the Program) on a volume of a
    storage or distribution medium does not bring the
    other work under the scope of this License.

      3. You may copy and distribute the Program (or
    a work based on it, under Section 2) in object
    code or executable form under the terms of
    Sections 1 and 2 above provided that you also do
    one of the following:

        a) Accompany it with the complete
        corresponding machine-readable source code,
        which must be distributed under the terms of
        Sections 1 and 2 above on a medium
        customarily used for software interchange;
        or,

        b) Accompany it with a written offer, valid
        for at least three years, to give any third
        party, for a charge no more than your cost of
        physically performing source distribution, a
        complete machine-readable copy of the
        corresponding source code, to be distributed
        under the terms of Sections 1 and 2 above on
        a medium customarily used for software
        interchange; or,

        c) Accompany it with the information you
        received as to the offer to distribute
        corresponding source code.  (This alternative
        is allowed only for noncommercial
        distribution and only if you received the
        program in object code or executable form
        with such an offer, in accord with Subsection
        b above.)

    The source code for a work means the preferred
    form of the work for making modifications to it.
    For an executable work, complete source code
    means all the source code for all modules it
    contains, plus any associated interface
    definition files, plus the scripts used to
    control compilation and installation of the
    executable.  However, as a special exception, the
    source code distributed need not include anything
    that is normally distributed (in either source or
    binary form) with the major components (compiler,
    kernel, and so on) of the operating system on
    which the executable runs, unless that component
    itself accompanies the executable.

    If distribution of executable or object code is
    made by offering access to copy from a designated
    place, then offering equivalent access to copy
    the source code from the same place counts as
    distribution of the source code, even though
    third parties are not compelled to copy the
    source along with the object code.

      4. You may not copy, modify, sublicense, or
    distribute the Program except as expressly
    provided under this License.  Any attempt
    otherwise to copy, modify, sublicense or
    distribute the Program is void, and will
    automatically terminate your rights under this
    License.  However, parties who have received
    copies, or rights, from you under this License
    will not have their licenses terminated so long
    as such parties remain in full compliance.

      5. You are not required to accept this License,
    since you have not signed it.  However, nothing
    else grants you permission to modify or
    distribute the Program or its derivative works.
    These actions are prohibited by law if you do not
    accept this License.  Therefore, by modifying or
    distributing the Program (or any work based on
    the Program), you indicate your acceptance of
    this License to do so, and all its terms and
    conditions for copying, distributing or modifying
    the Program or works based on it.

      6. Each time you redistribute the Program (or
    any work based on the Program), the recipient
    automatically receives a license from the
    original licensor to copy, distribute or modify
    the Program subject to these terms and
    conditions.  You may not impose any further
    restrictions on the recipients' exercise of the
    rights granted herein.  You are not responsible
    for enforcing compliance by third parties to this
    License.

      7. If, as a consequence of a court judgment or
    allegation of patent infringement or for any
    other reason (not limited to patent issues),
    conditions are imposed on you (whether by court
    order, agreement or otherwise) that contradict
    the conditions of this License, they do not
    excuse you from the conditions of this License.
    If you cannot distribute so as to satisfy
    simultaneously your obligations under this
    License and any other pertinent obligations, then
    as a consequence you may not distribute the
    Program at all.  For example, if a patent license
    would not permit royalty-free redistribution of
    the Program by all those who receive copies
    directly or indirectly through you, then the only
    way you could satisfy both it and this License
    would be to refrain entirely from distribution of
    the Program.

    If any portion of this section is held invalid or
    unenforceable under any particular circumstance,
    the balance of the section is intended to apply
    and the section as a whole is intended to apply
    in other circumstances.

    It is not the purpose of this section to induce
    you to infringe any patents or other property
    right claims or to contest validity of any such
    claims; this section has the sole purpose of
    protecting the integrity of the free software
    distribution system, which is implemented by
    public license practices.  Many people have made
    generous contributions to the wide range of
    software distributed through that system in
    reliance on consistent application of that
    system; it is up to the author/donor to decide if
    he or she is willing to distribute software
    through any other system and a licensee cannot
    impose that choice.

    This section is intended to make thoroughly clear
    what is believed to be a consequence of the rest
    of this License.

      8. If the distribution and/or use of the
    Program is restricted in certain countries either
    by patents or by copyrighted interfaces, the
    original copyright holder who places the Program
    under this License may add an explicit
    geographical distribution limitation excluding
    those countries, so that distribution is
    permitted only in or among countries not thus
    excluded.  In such case, this License
    incorporates the limitation as if written in the
    body of this License.

      9. The Free Software Foundation may publish
    revised and/or new versions of the General Public
    License from time to time.  Such new versions
    will be similar in spirit to the present version,
    but may differ in detail to address new problems
    or concerns.

    Each version is given a distinguishing version
    number.  If the Program specifies a version
    number of this License which applies to it and
    "any later version", you have the option of
    following the terms and conditions either of that
    version or of any later version published by the
    Free Software Foundation.  If the Program does
    not specify a version number of this License, you
    may choose any version ever published by the Free
    Software Foundation.

      10. If you wish to incorporate parts of the
    Program into other free programs whose
    distribution conditions are different, write to
    the author to ask for permission.  For software
    which is copyrighted by the Free Software
    Foundation, write to the Free Software
    Foundation; we sometimes make exceptions for
    this.  Our decision will be guided by the two
    goals of preserving the free status of all
    derivatives of our free software and of promoting
    the sharing and reuse of software generally.

    			    NO WARRANTY

      11. BECAUSE THE PROGRAM IS LICENSED FREE OF
    CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO
    THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT
    WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
    HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM
    "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
    EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED
    TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
    FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE
    RISK AS TO THE QUALITY AND PERFORMANCE OF THE
    PROGRAM IS WITH YOU.  SHOULD THE PROGRAM PROVE
    DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
    SERVICING, REPAIR OR CORRECTION.

      12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE
    LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT
    HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
    REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE
    LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL,
    SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES
    ARISING OUT OF THE USE OR INABILITY TO USE THE
    PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
    DATA OR DATA BEING RENDERED INACCURATE OR LOSSES
    SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF
    THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
    EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
    ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

    		     END OF TERMS AND CONDITIONS

    	    How to Apply These Terms to Your New
    	    Programs

      If you develop a new program, and you want it
    to be of the greatest possible use to the public,
    the best way to achieve this is to make it free
    software which everyone can redistribute and
    change under these terms.

      To do so, attach the following notices to the
    program.  It is safest to attach them to the
    start of each source file to most effectively
    convey the exclusion of warranty; and each file
    should have at least the "copyright" line and a
    pointer to where the full notice is found.

        <one line to give the program's name and a
        brief idea of what it does.> Copyright (C)
        yyyy <name of author>

        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 of the License, 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.

        You should have received a copy of the GNU
        General Public License along with this
        program; if not, write to the Free Software
        Foundation, Inc., 59 Temple Place, Suite 330,
        Boston, MA 02111-1307 USA

    Also add information on how to contact you by
    electronic and paper mail.

    If the program is interactive, make it output a
    short notice like this when it starts in an
    interactive mode:

        Gnomovision version 69, Copyright (C) yyyy
        name of author Gnomovision comes with
        ABSOLUTELY NO WARRANTY; for details type
        `show w'.  This is free software, and you are
        welcome to redistribute it under certain
        conditions; type `show c' for details.

    The hypothetical commands `show w' and `show c'
    should show the appropriate parts of the General
    Public License.  Of course, the commands you use
    may be called something other than `show w' and
    `show c'; they could even be mouse-clicks or menu
    items--whatever suits your program.

    You should also get your employer (if you work as
    a programmer) or your school, if any, to sign a
    "copyright disclaimer" for the program, if
    necessary.  Here is a sample; alter the names:

      Yoyodyne, Inc., hereby disclaims all copyright
      interest in the program `Gnomovision' (which
      makes passes at compilers) written by James
      Hacker.

      <signature of Ty Coon>, 1 April 1989
      Ty Coon, President of Vice

    This General Public License does not permit
    incorporating your program into proprietary
    programs.  If your program is a subroutine
    library, you may consider it more useful to
    permit linking proprietary applications with the
    library.  If this is what you want to do, use the
    GNU Library General Public License instead of
    this License.