# Chapter 11. The GNU General Public License

       1 		    GNU GENERAL PUBLIC LICENSE
       2 		       Version 2, June 1991
       3
       4  Copyright (C) 1989, 1991 Free Software Foundation, Inc.
       5                           675 Mass Ave, Cambridge, MA 02139, USA
       6  Everyone is permitted to copy and distribute verbatim copies
       7  of this license document, but changing it is not allowed.
       8
       9 			    Preamble
      10
      11   The licenses for most software are designed to take away your
      12 freedom to share and change it.  By contrast, the GNU General Public
      13 License is intended to guarantee your freedom to share and change free
      14 software--to make sure the software is free for all its users.  This
      15 General Public License applies to most of the Free Software
      16 Foundation's software and to any other program whose authors commit to
      17 using it.  (Some other Free Software Foundation software is covered by
      18 the GNU Library General Public License instead.)  You can apply it to
      19 your programs, too.
      20
      21   When we speak of free software, we are referring to freedom, not
      22 price.  Our General Public Licenses are designed to make sure that you
      23 have the freedom to distribute copies of free software (and charge for
      24 this service if you wish), that you receive source code or can get it
      25 if you want it, that you can change the software or use pieces of it
      26 in new free programs; and that you know you can do these things.
      27
      28   To protect your rights, we need to make restrictions that forbid
      29 anyone to deny you these rights or to ask you to surrender the rights.
      30 These restrictions translate to certain responsibilities for you if you
      31 distribute copies of the software, or if you modify it.
      32
      33   For example, if you distribute copies of such a program, whether
      34 gratis or for a fee, you must give the recipients all the rights that
      35 you have.  You must make sure that they, too, receive or can get the
      36 source code.  And you must show them these terms so they know their
      37 rights.
      38
      39   We protect your rights with two steps: (1) copyright the software, and
      40 (2) offer you this license which gives you legal permission to copy,
      41 distribute and/or modify the software.
      42
      43   Also, for each author's protection and ours, we want to make certain
      44 that everyone understands that there is no warranty for this free
      45 software.  If the software is modified by someone else and passed on, we
      46 want its recipients to know that what they have is not the original, so
      47 that any problems introduced by others will not reflect on the original
      48 authors' reputations.
      49
      50   Finally, any free program is threatened constantly by software
      51 patents.  We wish to avoid the danger that redistributors of a free
      52 program will individually obtain patent licenses, in effect making the
      53 program proprietary.  To prevent this, we have made it clear that any
      54 patent must be licensed for everyone's free use or not licensed at all.
      55
      56   The precise terms and conditions for copying, distribution and
      57 modification follow.
      58
      59 		    GNU GENERAL PUBLIC LICENSE
      60    TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
      61
      62   0. This License applies to any program or other work which contains
      63 a notice placed by the copyright holder saying it may be distributed
      64 under the terms of this General Public License.  The "Program", below,
      65 refers to any such program or work, and a "work based on the Program"
      66 means either the Program or any derivative work under copyright law:
      67 that is to say, a work containing the Program or a portion of it,
      68 either verbatim or with modifications and/or translated into another
      69 language.  (Hereinafter, translation is included without limitation in
      70 the term "modification".)  Each licensee is addressed as "you".
      71
      72 Activities other than copying, distribution and modification are not
      73 covered by this License; they are outside its scope.  The act of
      74 running the Program is not restricted, and the output from the Program
      75 is covered only if its contents constitute a work based on the
      76 Program (independent of having been made by running the Program).
      77 Whether that is true depends on what the Program does.
      78
      79   1. You may copy and distribute verbatim copies of the Program's
      80 source code as you receive it, in any medium, provided that you
      81 conspicuously and appropriately publish on each copy an appropriate
      82 copyright notice and disclaimer of warranty; keep intact all the
      83 notices that refer to this License and to the absence of any warranty;
      84 and give any other recipients of the Program a copy of this License
      85 along with the Program.
      86
      87 You may charge a fee for the physical act of transferring a copy, and
      88 you may at your option offer warranty protection in exchange for a fee.
      89
      90   2. You may modify your copy or copies of the Program or any portion
      91 of it, thus forming a work based on the Program, and copy and
      92 distribute such modifications or work under the terms of Section 1
      93 above, provided that you also meet all of these conditions:
      94
      95     a) You must cause the modified files to carry prominent notices
      96     stating that you changed the files and the date of any change.
      97
      98     b) You must cause any work that you distribute or publish, that in
      99     whole or in part contains or is derived from the Program or any
     100     part thereof, to be licensed as a whole at no charge to all third
     101     parties under the terms of this License.
     102
     103     c) If the modified program normally reads commands interactively
     104     when run, you must cause it, when started running for such
     105     interactive use in the most ordinary way, to print or display an
     106     announcement including an appropriate copyright notice and a
     107     notice that there is no warranty (or else, saying that you provide
     108     a warranty) and that users may redistribute the program under
     109     these conditions, and telling the user how to view a copy of this
     110     License.  (Exception: if the Program itself is interactive but
     111     does not normally print such an announcement, your work based on
     112     the Program is not required to print an announcement.)
     113
     114 These requirements apply to the modified work as a whole.  If
     115 identifiable sections of that work are not derived from the Program,
     116 and can be reasonably considered independent and separate works in
     117 themselves, then this License, and its terms, do not apply to those
     118 sections when you distribute them as separate works.  But when you
     119 distribute the same sections as part of a whole which is a work based
     120 on the Program, the distribution of the whole must be on the terms of
     121 this License, whose permissions for other licensees extend to the
     122 entire whole, and thus to each and every part regardless of who wrote it.
     123
     124 Thus, it is not the intent of this section to claim rights or contest
     125 your rights to work written entirely by you; rather, the intent is to
     126 exercise the right to control the distribution of derivative or
     127 collective works based on the Program.
     128
     129 In addition, mere aggregation of another work not based on the Program
     130 with the Program (or with a work based on the Program) on a volume of
     131 a storage or distribution medium does not bring the other work under
     132 the scope of this License.
     133
     134   3. You may copy and distribute the Program (or a work based on it,
     135 under Section 2) in object code or executable form under the terms of
     136 Sections 1 and 2 above provided that you also do one of the following:
     137
     138     a) Accompany it with the complete corresponding machine-readable
     139     source code, which must be distributed under the terms of Sections
     140     1 and 2 above on a medium customarily used for software interchange; or,
     141
     142     b) Accompany it with a written offer, valid for at least three
     143     years, to give any third party, for a charge no more than your
     144     cost of physically performing source distribution, a complete
     145     machine-readable copy of the corresponding source code, to be
     146     distributed under the terms of Sections 1 and 2 above on a medium
     147     customarily used for software interchange; or,
     148
     149     c) Accompany it with the information you received as to the offer
     150     to distribute corresponding source code.  (This alternative is
     151     allowed only for noncommercial distribution and only if you
     152     received the program in object code or executable form with such
     153     an offer, in accord with Subsection b above.)
     154
     155 The source code for a work means the preferred form of the work for
     156 making modifications to it.  For an executable work, complete source
     157 code means all the source code for all modules it contains, plus any
     158 associated interface definition files, plus the scripts used to
     159 control compilation and installation of the executable.  However, as a
     160 special exception, the source code distributed need not include
     161 anything that is normally distributed (in either source or binary
     162 form) with the major components (compiler, kernel, and so on) of the
     163 operating system on which the executable runs, unless that component
     164 itself accompanies the executable.
     165
     166 If distribution of executable or object code is made by offering
     167 access to copy from a designated place, then offering equivalent
     168 access to copy the source code from the same place counts as
     169 distribution of the source code, even though third parties are not
     170 compelled to copy the source along with the object code.
     171
     172   4. You may not copy, modify, sublicense, or distribute the Program
     173 except as expressly provided under this License.  Any attempt
     174 otherwise to copy, modify, sublicense or distribute the Program is
     175 void, and will automatically terminate your rights under this License.
     176 However, parties who have received copies, or rights, from you under
     177 this License will not have their licenses terminated so long as such
     178 parties remain in full compliance.
     179
     180   5. You are not required to accept this License, since you have not
     181 signed it.  However, nothing else grants you permission to modify or
     182 distribute the Program or its derivative works.  These actions are
     183 prohibited by law if you do not accept this License.  Therefore, by
     184 modifying or distributing the Program (or any work based on the
     185 Program), you indicate your acceptance of this License to do so, and
     186 all its terms and conditions for copying, distributing or modifying
     187 the Program or works based on it.
     188
     189   6. Each time you redistribute the Program (or any work based on the
     190 Program), the recipient automatically receives a license from the
     191 original licensor to copy, distribute or modify the Program subject to
     192 these terms and conditions.  You may not impose any further
     193 restrictions on the recipients' exercise of the rights granted herein.
     194 You are not responsible for enforcing compliance by third parties to
     195 this License.
     196
     197   7. If, as a consequence of a court judgment or allegation of patent
     198 infringement or for any other reason (not limited to patent issues),
     199 conditions are imposed on you (whether by court order, agreement or
     200 otherwise) that contradict the conditions of this License, they do not
     201 excuse you from the conditions of this License.  If you cannot
     202 distribute so as to satisfy simultaneously your obligations under this
     203 License and any other pertinent obligations, then as a consequence you
     204 may not distribute the Program at all.  For example, if a patent
     205 license would not permit royalty-free redistribution of the Program by
     206 all those who receive copies directly or indirectly through you, then
     207 the only way you could satisfy both it and this License would be to
     208 refrain entirely from distribution of the Program.
     209
     210 If any portion of this section is held invalid or unenforceable under
     211 any particular circumstance, the balance of the section is intended to
     212 apply and the section as a whole is intended to apply in other
     213 circumstances.
     214
     215 It is not the purpose of this section to induce you to infringe any
     216 patents or other property right claims or to contest validity of any
     217 such claims; this section has the sole purpose of protecting the
     218 integrity of the free software distribution system, which is
     219 implemented by public license practices.  Many people have made
     220 generous contributions to the wide range of software distributed
     221 through that system in reliance on consistent application of that
     222 system; it is up to the author/donor to decide if he or she is willing
     223 to distribute software through any other system and a licensee cannot
     224 impose that choice.
     225
     226 This section is intended to make thoroughly clear what is believed to
     227 be a consequence of the rest of this License.
     228
     229   8. If the distribution and/or use of the Program is restricted in
     230 certain countries either by patents or by copyrighted interfaces, the
     231 original copyright holder who places the Program under this License
     232 may add an explicit geographical distribution limitation excluding
     233 those countries, so that distribution is permitted only in or among
     234 countries not thus excluded.  In such case, this License incorporates
     235 the limitation as if written in the body of this License.
     236
     237   9. The Free Software Foundation may publish revised and/or new versions
     238 of the General Public License from time to time.  Such new versions will
     239 be similar in spirit to the present version, but may differ in detail to
     240 address new problems or concerns.
     241
     242 Each version is given a distinguishing version number.  If the Program
     243 specifies a version number of this License which applies to it and "any
     244 later version", you have the option of following the terms and conditions
     245 either of that version or of any later version published by the Free
     246 Software Foundation.  If the Program does not specify a version number of
     247 this License, you may choose any version ever published by the Free Software
     248 Foundation.
     249
     250   10. If you wish to incorporate parts of the Program into other free
     251 programs whose distribution conditions are different, write to the author
     252 to ask for permission.  For software which is copyrighted by the Free
     253 Software Foundation, write to the Free Software Foundation; we sometimes
     254 make exceptions for this.  Our decision will be guided by the two goals
     255 of preserving the free status of all derivatives of our free software and
     256 of promoting the sharing and reuse of software generally.

       1 			    NO WARRANTY
       2
       3   11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
       4 FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
       5 OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
       6 PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
       7 OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
       8 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
       9 TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
      10 PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
      11 REPAIR OR CORRECTION.
      12
      13   12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
      14 WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
      15 REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
      16 INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
      17 OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
      18 TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
      19 YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
      20 PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
      21 POSSIBILITY OF SUCH DAMAGES.
      22
      23 		     END OF TERMS AND CONDITIONS