Location: PHPKode > projects > CodeTrack: Web-based Bug Tracking > codetrack_v99-4/docs/GPL_FAQ.html
<html><head><title>GNU Public License FAQ</title></head><body>

<h2>Frequently Asked Questions about the GNU Public License (GPL)</h2>

<h3>Source version is: <a href="http://www.gnu.org/licenses/gpl-faq.html">http://www.gnu.org/licenses/gpl-faq.html</a></h2>

<h4>Table of Contents</h4>
<ul>
  <h4>Basic questions about the GPL, the GNU Project, and the Free
  Software Foundation</h4>

  <ul>
    <li><a HREF="#WhatDoesGPLStandFor" NAME="TOCWhatDoesGPLStandFor">What
    does "GPL" stand for?</a>

    <li><a HREF="#DoesFreeSoftwareMeanUsingTheGPL"
    NAME="TOCDoesFreeSoftwareMeanUsingTheGPL">Does free software mean
    using the GPL?</a>

    <li><a HREF="#WhyUseGPL" NAME="TOCWhyUseGPL">Why should I use the GNU GPL
    rather than other free software licenses?</a>

    <li><a HREF="#DoesAllGNUSoftwareUseTheGNUGPLAsItsLicense"
    NAME="TOCDoesAllGNUSoftwareUseTheGNUGPLAsItsLicense">Does all GNU
    software use the GNU GPL as its license?</a>

    <li><a HREF="#DoesUsingTheGPLForAProgramMakeItGNUSoftware"
    NAME="TOCDoesUsingTheGPLForAProgramMakeItGNUSoftware">Does using the
    GPL for a program make it GNU software?</a>

    <li><a HREF="#GPLOtherThanSoftware" NAME="TOCGPLOtherThanSoftware">Can
    I use the GPL for something other than software?</a>
  
    <li><a HREF="#WhyNotGPLForManuals" NAME="TOCWhyNotGPLForManuals">Why
    don't you use the GPL for manuals?</a>

  
    <li><a HREF="#GPLTranslations" NAME="TOCGPLTranslations">Are there
    translations of the GPL into other languages?</a>
  
    <li><a HREF="#WhySomeGPLAndNotLGPL" NAME="TOCWhySomeGPLAndNotLGPL">Why
    are some GNU libraries released under the ordinary GPL rather than the
    Lesser GPL?</a>
  
    <li><a HREF="#WhoHasThePower" NAME="TOCWhoHasThePower">Who has the
    power to enforce the GPL?</a>
  
    <li><a HREF="#AssignCopyright" NAME="TOCAssignCopyright">Why does the
    FSF require that contributors to FSF-copyrighted programs assign
    copyright to the FSF?  If I hold copyright on a GPL'ed program, should
    I do this, too?  If so, how?</a>
  
    <li><a HREF="#ModifyGPL" NAME="TOCModifyGPL">Can I modify the GPL
    and make a modified license?</a>

  </ul>

  <h4>General understanding of the GPL</h4>
  
  <ul>
    <li><a HREF="#WhyDoesTheGPLPermitUsersToPublishTheirModifiedVersions"
    NAME="TOCWhyDoesTheGPLPermitUsersToPublishTheirModifiedVersions">Why does
    the GPL permit users to publish their modified versions?</a>
  
    <li><a HREF="#GPLRequireSourcePostedPublic"
    NAME="TOCGPLRequireSourcePostedPublic">Does
    the GPL require that source code of modified versions be posted to the public?</a>
  
    <li><a HREF="#GPLAndNonfreeOnSameMachine"
    NAME="TOCGPLAndNonfreeOnSameMachine"> Can I have a GPL-covered
    program and an unrelated non-free program on the same
    computer?</a>
  
    <li><a HREF="#CanIDemandACopy" NAME="TOCCanIDemandACopy">If I know
    someone has a copy of a GPL-covered program, can I demand he give
    me a copy?</a>

    <li><a HREF="#WhatDoesWrittenOfferValid" NAME="TOCWhatDoesWrittenOfferValid">What
    does this "written offer valid for any third party" mean? Does that mean everyone
    in the world can get the source to any GPL'ed program no matter what?</a>

    <li><a HREF="#TheGPLSaysModifiedVersions" NAME="TOCTheGPLSaysModifiedVersions">The
    GPL says that modified versions, if released, must be "licensed ... to all third
    parties." Who are these third parties?</a>
  
    <li><a HREF="#DoesTheGPLAllowMoney" NAME="TOCDoesTheGPLAllowMoney">Does
    the GPL allow me to sell copies of the program for money?</a>
  
    <li><a HREF="#DoesTheGPLAllowDownloadFee"
    NAME="TOCDoesTheGPLAllowDownloadFee"> Does the GPL allow me to
    charge a fee for downloading the program from my site?</a>
  
    <li><a HREF="#DoesTheGPLAllowRequireFee" NAME="TOCDoesTheGPLAllowRequireFee">

    Does the GPL allow me to require that anyone who receives the software
    must pay me a fee and/or notify me?</a>
  
    <li><a HREF="#DoesTheGPLRequireAvailabilityToPublic"
    NAME="TOCDoesTheGPLRequireAvailabilityToPublic">If I distribute GPL'd
    software for a fee, am I required to also make it available to the
    public without a charge?</a>
  
    <li><a HREF="#DoesTheGPLAllowNDA" NAME="TOCDoesTheGPLAllowNDA">Does
    the GPL allow me to distribute a modified or beta version under a
    nondisclosure agreement?</a>
  
    <li><a HREF="#DevelopChangesUnderNDA" NAME="TOCDevelopChangesUnderNDA">Does
    the GPL allow me to develop a modified version under a
    nondisclosure agreement?</a>

    <li><a HREF="#WhyMustIInclude" NAME="TOCWhyMustIInclude">Why does the GPL
    require including a copy of the GPL with every copy of the program?</a>
  
    <li><a HREF="#WhatIfWorkIsShort" NAME="TOCWhatIfWorkIsShort">What
    if the work is not much longer than the license itself?</a>

  
    <li><a href="#RequiredToClaimCopyright"
    NAME="TOCRequiredToClaimCopyright">Am I required to claim a copyright on
    my modifications to a GPL-covered program?</a>
  
    <li><a href="#CombinePublicDomainWithGPL"
    name="TOCCombinePublicDomainWithGPL">If a program combines public-domain
    code with GPL-covered code, can I take the public-domain part and use it
    as public domain code?</a>
  
    <li><a HREF="#IWantCredit" NAME="TOCIWantCredit">I want to get credit for my work. I
    want people to know what I wrote. Can I still get credit if I use the GPL?</a>
  
    <li><a HREF="#GPLOmitPreamble" NAME="TOCGPLOmitPreamble">Can I omit the
    preamble of the GPL, or the instructions for how to use it on your own
    programs, to save space?</a>
  
    <li><a HREF="#WhatIsCompatible" NAME="TOCWhatIsCompatible">What does it mean to
    say that two licenses are compatible?</a>
  
    <li><a HREF="#WhatDoesCompatMean" NAME="TOCWhatDoesCompatMean">What
    does it mean to say a license is "compatible with the GPL"?</a>

  
    <li><a HREF="#OrigBSD" NAME="TOCOrigBSD">Why is the original BSD
    license incompatible with the GPL?</a>

    <li><a HREF="#MereAggregation" NAME="TOCMereAggregation">What is the
    difference between "mere aggregation" and "combining two modules into
    one program"?</a>
  
    <li><a HREF="#AssignCopyright" NAME="TOCAssignCopyright">Why does the
    FSF require that contributors to FSF-copyrighted programs assign
    copyright to the FSF?  If I hold copyright on a GPL'ed program, should
    I do this, too?  If so, how?</a>
  
    <li><a HREF="#GPLCommercially" NAME="TOCGPLCommercially">If I use a
    piece of software that has been obtained under the GNU GPL, am I
    allowed to modify the original code into a new program, then
    distribute and sell that new program commercially?</a>

    <li><a HREF="#GPLOtherThanSoftware" NAME="TOCGPLOtherThanSoftware">Can
    I use the GPL for something other than software?</a>

  
  </ul>

  <h4>Using the GPL for your programs</h4>

  <ul>

    <li><a HREF="#CouldYouHelpApplyGPL" NAME="TOCCouldYouHelpApplyGPL">Could
    you give me step by step instructions on how to apply the GPL to my
    program?</a>

    <li><a HREF="#WhyUseGPL" NAME="TOCWhyUseGPL">Why should I use the GNU GPL
    rather than other free software licenses?</a>

    <li><a HREF="#WhyMustIInclude" NAME="TOCWhyMustIInclude">Why does the GPL
    require including a copy of the GPL with every copy of the program?</a>
  
    <li><a HREF="#WhatIfWorkIsShort" NAME="TOCWhatIfWorkIsShort">What
    if the work is not much longer than the license itself?</a>
  
    <li><a HREF="#GPLOmitPreamble" NAME="TOCGPLOmitPreamble">Can I omit the
    preamble of the GPL, or the instructions for how to use it on your own
    programs, to save space?</a>

    <li><a HREF="#HowIGetCopyright" NAME="TOCHowIGetCopyright">How do I
    get a copyright on my program in order to release it under the
    GPL?</a>
  
    <li><a HREF="#WhatIfSchool" NAME="TOCWhatIfSchool">What if my school
    might want to make my program into its own proprietary software
    product?</a>

    <li><a HREF="#ReleaseUnderGPLAndNF" NAME="TOCReleaseUnderGPLAndNF">I
    would like to release a program I wrote under the GNU GPL, but I would
    like to use the same code in non-free programs.</a>
  
    <li><a HREF="#CanDeveloperThirdParty"
    NAME="TOCCanDeveloperThirdParty">Can the developer of a program who
    distributed it under the GPL later license it to another party for
    exclusive use?</a>
  
    <li><a HREF="#GPLUSGov" NAME="TOCGPLUSGov">Can the US Government
    release a program under the GNU GPL?</a>

    <li><a HREF="#GPLUSGovAdd" NAME="TOCGPLUSGovAdd">Can the US Government
    release improvements to a GPL-covered program?</a>
  
    <li><a HREF="#VersionTwoOrLater" NAME="TOCVersionTwoOrLater">Why should
    programs say "Version 2 of the GPL or any later version"?</a>

  
    <li><a HREF="#GPLOutput" NAME="TOCGPLOutput">Is there some way that I
    can GPL the output people get from use of my program?  For example, if
    my program is used to develop hardware designs, can I require these
    these designs must be free?</a>
  
    <li><a HREF="#WhyNotGPLForManuals" NAME="TOCWhyNotGPLForManuals">Why
    don't you use the GPL for manuals?</a>
  
  </ul>

  <h4>Distribution of programs released under the GPL</h4>

  <ul>

    <li><a HREF="#ModifiedJustBinary"
    NAME="TOCModifiedJustBinary">Can I release a modified
    version of a GPL-covered program in binary form only?</a>

    <li><a HREF="#DistributeWithSourceOnInternet"
    NAME="TOCDistributeWithSourceOnInternet">I want to distribute
    binaries without accompanying sources.  Can I provide source code by
    FTP instead of by mail order?</a>

    <li><a HREF="#RedistributedBinariesGetSource"
    NAME="TOCRedistributedBinariesGetSource">My friend got a GPL-covered
    binary with an offer to supply source, and made a copy for me.
    Can I use the offer to obtain the source?</a>
  
    <li><a HREF="#SourceAndBinaryOnDifferentSites"
    NAME="TOCSourceAndBinaryOnDifferentSites">Can I put the binaries on my
    Internet server and put the source on a different Internet site?</a>
  
    <li><a HREF="#DistributeExtendedBinary"
    NAME="TOCDistributeExtendedBinary">I want to distribute an extended
    version of a GPL-covered program in binary form.  Is it enough to
    distribute the source for the original version?</a>
  
    <li><a HREF="#DistributingSourceIsInconvenient"
    NAME="TOCDistributingSourceIsInconvenient">I want to distribute
    binaries, but distributing complete source is inconvenient.  Is it
    ok if I give users the diffs from the "standard" version along with the
    binaries?</a>

  
    <li><a HREF="#AnonFTPAndSendSources" NAME="TOCAnonFTPAndSendSource">I
    want to make binaries available for anonymous FTP, but send sources
    only to people who order them.</a>

    <li><a HREF="#HowCanIMakeSureEachDownloadGetsSource"
    NAME="TOCHowCanIMakeSureEachDownloadGetsSource">How can I make sure
    each user who downloads the binaries also gets the source?</a>

    <li><a HREF="#ReleaseNotOriginal" NAME="TOCReleaseNotOriginal"> Can
    I release a program with a license which says that you can distribute
    modified versions of it under the GPL but you can't distribute the 
    original itself under the GPL?</a>

    <li><a HREF="#CompanyGPLCostsMoney" NAME="TOCCompanyGPLCostsMoney">  I
    just found out that a company has a copy of a GPL'ed program, and it
    costs money to get it.  Aren't they violating the GPL by not making it   
    available on the Internet?</a>

    <li><a HREF="#UnreleasedMods" NAME="TOCUnreleasedMods">  A company
    is running a modified version of a GPL'ed program on a web site.
    Does the GPL say they must release their modified sources?</a>

    <li><a HREF="#InternalDistribution" NAME="TOCInternalDistribution">
    Is use within one organization or company "distribution"?</a>

    <li><a HREF="#StolenCopy" NAME="TOCStolenCopy">
    If someone steals a CD containing a version of a GPL-covered
    program, does the GPL give him the right to redistribute that
    version?</a>

    <li><a HREF="#TradeSecretRelease" NAME="TOCTradeSecretRelease">
    What if a company distributes a copy as a trade secret?</a>

    <li><a HREF="#GPLFairUse" NAME="TOCGPLFairUse">Do I have "fair use"
    rights in using the source code of a GPL-covered program?</a>

  </ul>

  <h4>Using programs released under the GPL when writing other
  programs</h4>

  <ul>

    <li><a HREF="#GPLAndNonfreeOnSameMachine"
    NAME="TOCGPLAndNonfreeOnSameMachine"> Can I have a GPL-covered
    program and an unrelated non-free program on the same
    computer?</a>

    <li><a HREF="#CanIUseGPLToolsForNF" NAME="TOCCanIUseGPLToolsForNF">Can
    I use GPL-covered editors such as GNU Emacs to develop non-free
    programs?  Can I use GPL-covered tools such as GCC to compile
    them?</a>
  
    <li><a HREF="#GPLOutput" NAME="TOCGPLOutput">Is there some way that I
    can GPL the output people get from use of my program?  For example, if
    my program is used to develop hardware designs, can I require these
    these designs must be free?</a>
  
    <li><a HREF="#WhatCaseIsOutputGPL" NAME="TOCWhatCaseIsOutputGPL">In
    what cases is the output of a GPL program covered by the GPL too?</a>

    <li><a HREF="#PortProgramToGL" NAME="TOCPortProgramToGL">If I port my
    program to GNU/Linux, does that mean I have to release it as Free
    Software under the GPL or some other Free Software license?</a>
  
    <li><a HREF="#GPLInProprietarySystem"
    NAME="TOCGPLInProprietarySystem">I'd like to incorporate GPL-covered
    software in my proprietary system.  Can I do this?</a>
  
  </ul>

  <h4>Combining work with code released under the GPL</h4>

  <ul>

    <li><a HREF="#MereAggregation" NAME="TOCMereAggregation">What is the
    difference between "mere aggregation" and "combining two modules into
    one program"?</a>
  
    <li><a HREF="#GPLFairUse" NAME="TOCGPLFairUse">Do I have "fair use"
    rights in using the source code of a GPL-covered program?</a>

    <li><a HREF="#GPLUSGovAdd" NAME="TOCGPLUSGovAdd">Can the US Government
    release improvements to a GPL-covered program?</a>

    <li><a HREF="#IfLibraryIsGPL" NAME="TOCIfLibraryIsGPL">If a library is
    released under the GPL (not the LGPL), does that mean that any program
    which uses it has to be under the GPL?</a>
  
    <li><a HREF="#LinkingWithGPL" NAME="TOCLinkingWithGPL">You have a
    GPL'ed program that I'd like to link with my code to build a
    proprietary program.  Does the fact that I link with your program mean
    I have to GPL my program?</a>

  
    <li><a HREF="#SwitchToLGPL" NAME="TOCSwitchToLGPL">If so, is there any
    chance I could get a license of your program under the Lesser GPL?</a>
  
    <li><a HREF="#WillYouMakeAnException"
    NAME="TOCWillYouMakeAnException">Using a certain GNU program under the
    GPL does not fit our project to make proprietary software.  Will you
    make an exception for us?  It would mean more users of that
    program.</a>
  
    <li><a href="#IfInterpreterIsGPL" name="TOCIfInterpreterIsGPL">If a
    programming language interpreter is released under the GPL, does that
    mean programs written to be interpreted by it must be under
    GPL-compatible licenses?</a>
  
    <li><a HREF="#InterpreterIncompat" NAME="TOCInterpreterIncompat">If a
    programming language interpreter has a license that is incompatible
    with the GPL, can I run GPL-covered programs on it?</a>
  
    <li><a HREF="#GPLModuleLicense" NAME="TOCGPLModuleLicense">If I add a
    module to a GPL-covered program, do I have to use the GPL as the
    license for my module?</a>
  
    <li><a HREF="#GPLAndPlugins" NAME="TOCGPLAndPlugins">If a program
    released under the GPL uses plug-ins, what are the requirements for
    the licenses of a plug-in?</a>

  
    <li><a HREF="#GPLPluginsInNF" NAME="TOCGPLPluginsInNF">Can I use the
    GPL for a plug-in for a non-free program?</a>
  
    <li><a HREF="#GPLInProprietarySystem"
    NAME="TOCGPLInProprietarySystem">I'd like to incorporate GPL-covered
    software in my proprietary system.  Can I do this?</a>
  
    <li><a HREF="#FSWithNFLibs" NAME="TOCFSWithNFLibs"> Can I write
    free software that uses non-free libraries?</a>

    <li><a HREF="#GPLIncompatibleLibs" NAME="TOCGPLIncompatibleLibs">
    What legal issues come up if I use GPL-incompatible libraries with
    GPL software?</a>
  
    <li><a HREF="#WindowsRuntimeAndGPL" NAME="TOCWindowsRuntimeAndGPL">I'm
    writing a Windows application with Microsoft Visual C++ and I will be
    releasing it under the GPL.  Is dynamically linking my program with
    the Visual C++ run-time library permitted under the GPL?</a>

  
    <li><a HREF="#MoneyGuzzlerInc" NAME="TOCMoneyGuzzlerInc">I'd like
    to modify GPL-covered programs and link them with the portability
    libraries from Money Guzzler Inc.  I cannot distribute the source
    code for these libraries, so any user who wanted to change these
    versions would have to obtain those libraries separately.  Why
    doesn't the GPL permit this?</a>
  
    <li><a href="#GPLIncompatibleAlone" name="TOCGPLIncompatibleAlone">If
    license for a module Q has a requirement that's incompatible with the
    GPL, but the requirement applies only when Q is distributed by itself,
    not when Q is included in a larger program, does that make the license
    GPL-compatible?  Can I combine or link Q with a GPL-covered
    program?</a>

    <li><a HREF="#OOPLang" NAME="TOCOOPLANG"> In an object-oriented
    language such as Java, if I use a class that is GPL'ed without
    modifying, and subclass it, in what way does the GPL affect the larger
    program?</a>
  
    <li><a href="#LinkingOverControlledInterface"
    name="TOCLinkingOverControlledInterface">How can I allow linking of
    proprietary modules with my GPL-covered library under a controlled
    interface only?</a>
  
    <li><a HREF="#Consider" NAME="TOCConsider">Consider this situation:
      <ul>

        <li>X releases V1 of a project under the GPL.
        <li>Y contributes to the development of V2 with
              changes and new code based on V1.
       <li>X wants to convert V2 to a non-GPL license.
     </ul>
     Does X need Y's permission?</a>
  
    <li><a HREF="#ManyDifferentLicenses" NAME="TOCManyDifferentLicenses">I
    have written an application that links with many different components,
    that have different licenses.  I am very confused as to what licensing
    requirements are placed on my program.  Can you please tell me what
    licenses I may use?</a>
  
  </ul>

  <h4>Questions about violations of the GPL</h4>

  <ul>

    <li><a href="#ReportingViolation" name="TOCReportingViolation">What
    should I do if I discover a possible violation of the GPL?</a>

    <li><a HREF="#WhoHasThePower" NAME="TOCWhoHasThePower">Who has the
    power to enforce the GPL?</a>
  
    <li><a HREF="#HeardOtherLicense" NAME="TOCHeardOtherLicense">I heard
    that someone got a copy of a GPL'ed program under another license.  Is
    this possible?</a>
  
    <li><a HREF="#DeveloperViolate" NAME="TOCDeveloperViolate">Is the
    developer of a GPL-covered program bound by the GPL?  Could the
    developer's actions ever be a violation of the GPL?</a>

  
    <li><a HREF="#CompanyGPLCostsMoney" NAME="TOCCompanyGPLCostsMoney">  I
    just found out that a company has a copy of a GPL'ed program, and it
    costs money to get it.  Aren't they violating the GPL by not making it   
    available on the Internet?</a>

  </ul>

</ul>

<p>
<hr>
<p>


<dt><h4><a HREF="#TOCWhatDoesGPLStandFor" NAME="WhatDoesGPLStandFor">What does "GPL" stand for?</a></h4>

<dd>"GPL" stands for "General Public License".  The most widespread such
license is the GNU General Public License, or GNU GPL for short.  This
can be further shortened to "GPL", when it is understood that the GNU
GPL is the one intended.

<p>

<dt><h4><a HREF="#TOCDoesFreeSoftwareMeanUsingTheGPL" NAME="DoesFreeSoftwareMeanUsingTheGPL">
Does free software mean using the GPL?</a></h4>

<dd>
Not at all--there are many other free software licenses.  We have an
<a HREF="http://www.gnu.org/licenses/license-list.html"> incomplete
list</a>.  Any license that provides the user <a
HREF="http://www.gnu.org/philosophy/free-sw.html">certain specific
freedoms</a> is a free software license.
<p>

<dt><h4><a HREF="#TOCWhyUseGPL" NAME="WhyUseGPL">
Why should I use the GNU GPL rather than other free software licenses?</a></h4>

<dd>
Using the GNU GPL will require that all the <a
HREF="http://www.gnu.org/philosophy/pragmatic.html">released improved versions be free
software</a>.  This means you can avoid the risk of having to compete
with a proprietary modified version of your own work.  However, in
some special situations it can be better to use a
<a HREF="http://www.gnu.org/licenses/why-not-lgpl.html"> more permissive license</a>.
<p>

<dt><h4><a HREF="#TOCDoesAllGNUSoftwareUseTheGNUGPLAsItsLicense" NAME="DoesAllGNUSoftwareUseTheGNUGPLAsItsLicense">
Does all GNU software use the GNU GPL as its license?</a></h4>

<dd>
Most GNU software packages use the GNU GPL, but there are a few
GNU programs (and parts of programs) that use looser licenses, such as the
Lesser GPL.  When we do this, it is a matter of <a
HREF="http://www.gnu.org/licenses/why-not-lgpl.html"> strategy</a>.
<p>

<dt><h4><a HREF="#TOCDoesUsingTheGPLForAProgramMakeItGNUSoftware" NAME="DoesUsingTheGPLForAProgramMakeItGNUSoftware">
Does using the GPL for a program make it GNU software?</a></h4>

<dd>
Anyone can release a program under the GNU GPL but that does not
make it a GNU package.
<p>
Making the program a GNU software package means explicitly
contributing to the GNU Project.  This happens when the program's
developers and the GNU Project agree to do it.  If you are interested
in contributing a program to the GNU Project, please write to
<a HREF="mailto:hide@address.com">&lt;hide@address.com&gt;</a>.

<p>

<dt><h4><a HREF="#TOCReportingViolation" NAME="ReportingViolation">
What should I do if I discover a possible violation of the GPL?</a></h4>

<dd>
You should <a HREF="http://www.gnu.org/licenses/gpl-violation.html">report it.</a>
First, check the facts as best you can.  Then tell the publisher or
copyright holder of the specific GPL-covered program.  If that is the
Free Software Foundation, write to <a
HREF="mailto:license-hide@address.com">&lt;license-hide@address.com&gt;</a>.  
Otherwise, the program's maintainer may be the copyright holder, or
else could tell you how to contact the copyright holder, so report it
to the maintainer.
<p>

<dt><h4><a HREF="#TOCWhyDoesTheGPLPermitUsersToPublishTheirModifiedVersions" NAME="WhyDoesTheGPLPermitUsersToPublishTheirModifiedVersions">
Why does the GPL permit users to publish their modified versions?</a></h4>

<dd>
A crucial aspect of free software is that users are free to cooperate.
It is absolutely essential to permit users who wish to help each other
to share their bug fixes and improvements with other users.
<p>
Some have proposed alternatives to the GPL that require modified
versions to go through the original author.  As long as the original
author keeps up with the need for maintenance, this may work well in
practice, but if the author stops (more or less) to do something else
or does not attend to all the users' needs, this scheme falls down.
Aside from the practical problems, this scheme does not allow users to
help each other.
<p>
Sometimes control over modified versions is proposed as a means of
preventing confusion between various versions made by users.  In our
experience, this confusion is not a major problem.  Many versions of
Emacs have been made outside the GNU Project, but users can tell them
apart.  The GPL requires the maker of a version to place his or her
name on it, to distinguish it from other versions and to protect the
reputations of other maintainers.
<p>

<dt><h4><a HREF="#TOCGPLRequireSourcePostedPublic"
        NAME="GPLRequireSourcePostedPublic">
        Does the GPL require that source code of modified versions be
        posted to the public?</a></h4>

<dd>
The GPL does not require you to release your modified version.  You are
free to make modifications and use them privately, without ever
releasing them.  This applies to organizations (including companies),
too; an organization can make a modified version and use it internally
without ever releasing it outside the organization.
<p>

But <em>if</em> you release the modified version to the public in some
way, the GPL requires you to make the modified source code available
to the program's users, under the GPL.
<p>
Thus, the GPL gives permission to release the modified program in
certain ways, and not in other ways; but the decision of whether to
release it is up to you.
<p>


<dt><h4><a HREF="#TOCGPLAndNonfreeOnSameMachine" NAME="GPLAndNonfreeOnSameMachine">
        Can I have a GPL-covered program and an unrelated non-free program on the same computer?</a></h4>
<dd>
Yes.  The "mere aggregation" clause in the GPL makes this permission
explicit, but that only reinforces what we believe would be true
anyway.
<p>

<dt><h4><a HREF="#TOCCanIDemandACopy" NAME="CanIDemandACopy">If I know
    someone has a copy of a GPL-covered program, can I demand he give
    me a copy?</a></h4>

<dd>
No.  The GPL gives him permission to make and redistribute copies of
the program <em>if he chooses to do so</em>.  He also has the right
not to redistribute the program, if that is what he chooses.
<p>

<dt><h4><a HREF="#TOCWhatDoesWrittenOfferValid" NAME="WhatDoesWrittenOfferValid">
        What does this "written offer valid for any third party" mean?
        Does that mean everyone in the world can get the source to any
        GPL'ed program no matter what?</a></h4>

<dd>
"Valid for any third party" means that anyone who has the offer
is entitled to take you up on it.
<p>

If you commercially distribute binaries not accompanied with source
code, the GPL says you must provide a written offer to distribute the
source code later.  When users non-commercially redistribute the
binaries they received from you, they must pass along a copy of this
written offer.  This means that people who did not get the binaries
directly from you can still receive copies of the source code, along with
the written offer.
<p>
The reason we require the offer to be valid for any third party
is so that people who receive the binaries indirectly in that way
can order the source code from you.
<p>

<dt><h4><a HREF="#TOCTheGPLSaysModifiedVersions" NAME="TheGPLSaysModifiedVersions">The
        GPL says that modified versions, if released, must be
        "licensed ... to all third parties."  Who are these third parties?</a></h4>

<dd>
Section 2 says that modified versions you distribute must be licensed
to all third parties under the GPL.  "All third parties" means
absolutely everyone--but this does not require you to *do* anything
physically for them.  It only means they have a license from you,
under the GPL, for your version.
<p>

<dt><h4><a href="#TOCRequiredToClaimCopyright"
        name="RequiredToClaimCopyright">Am I required to claim a copyright
        on my modifications to a GPL-covered program?</a></h4>

<dd>
You are not required to claim a copyright on your changes.  In most
countries, however, that happens automatically by default, so you need to
place your changes explicitly in the public domain if you do not want them
to be copyrighted.

<p>
Whether you claim a copyright on your changes or not, either way you
must release the modified version, as a whole, under the GPL. (<a
href="#GPLRequireSourcePostedPublic">if you release your modified
version at all</a>)
<p>


<dt><h4><a href="#TOCCombinePublicDomainWithGPL"
        name="CombinePublicDomainWithGPL">If a program combines
        public-domain code with GPL-covered code, can I take the
        public-domain part and use it as public domain code?</a></h4>

<dd>
You can do that, if you can figure out which part is the public domain
part and separate it from the rest.  If code was put in the public
domain by its developer, it is in the public domain no matter where it
has been.
<p>

<dt><h4><a HREF="#TOCDoesTheGPLAllowMoney" NAME="DoesTheGPLAllowMoney">
        Does the GPL allow me to sell copies of the program for money?</a></h4>

<dd>
Yes, the GPL allows everyone to do this.  The <a
HREF="http://www.gnu.org/philosophy/selling.html"> right to sell copies </a> is part of
the definition of free software.  Except in one special situation,
there is no limit on what price you can charge.  (The one exception is
the required written offer to provide source code that must accompany
binary-only release.)
<p>

<dt><h4><a HREF="#TOCDoesTheGPLAllowDownloadFee" NAME="DoesTheGPLAllowDownloadFee">
	Does the GPL allow me to
	charge a fee for downloading the program from my site?</a></h4>

<dd>
Yes.  You can charge any fee you wish for distributing a copy of the
program.  If you distribute binaries by download, you must provide
"equivalent access" to download the source--therefore, the fee to
download source may not be greater than the fee to download the binary.
<p>

<dt><h4><a HREF="#TOCDoesTheGPLAllowRequireFee" NAME="DoesTheGPLAllowRequireFee">
        Does the GPL allow me to require that anyone who receives the software
        must pay me a fee and/or notify me?</a></h4>

<dd>
No.  In fact, a requirement like that would make the program non-free.
If people have to pay when they get a copy of a program, or if they
have to notify anyone in particular, then the program is not free.
See the <a HREF="http://www.gnu.org/philosophy/free-sw.html">
definition of free software</a>.
<p>
The GPL is a free software license, and therefore it permits people
to use and even redistribute the software without being required to
pay anyone a fee for doing so.
<p>

<dt><h4><a HREF="#TOCDoesTheGPLRequireAvailabilityToPublic"
  NAME="DoesTheGPLRequireAvailabilityToPublic">If I
  distribute GPL'd software for a fee, am I required to also make
  it available to the public without a charge?</a></h4>

<dd>
No.  However, if someone pays your fee and gets a copy, the GPL gives
them the freedom to release it to the public, with or without a fee.
For example, someone could pay your fee, and then put her copy on a
web site for the general public.
<p>

<dt><h4><a HREF="#TOCDoesTheGPLAllowNDA" NAME="DoesTheGPLAllowNDA">
  Does the GPL allow me to distribute a modified or beta version under a
  nondisclosure agreement?</a></h4>

<dd>
No.  The GPL says that anyone who receives a copy of your version from you
has the right to redistribute copies (modified or not) of that version.
It does not give you permission to distribute the work on any more
restrictive basis.
<p>

<dt><h4><a HREF="#TOCDevelopChangesUnderNDA" NAME="DevelopChangesUnderNDA">
  Does the GPL allow me to develop a modified version under a
  nondisclosure agreement?</a></h4>

<dd>
Yes.  For instance, you can accept a contract to develop changes and
agree not to release <em>your changes</em> until the client says ok.
This is permitted because in this case no GPL-covered code is
being distributed under an NDA.
<p>
You can also release your changes to the client under the GPL, but
agree not to release them to anyone else unless the client says ok.  In
this case, too, no GPL-covered code is being distributed under an NDA,
or under any additional restrictions.
<p>
The GPL would give the client the right to redistribute your version.
In this scenario, the client will probably choose not to exercise that right,
but does <em>have</em> the right.
<p>

<dt><h4><a HREF="#TOCIWantCredit" NAME="IWantCredit">I want to get credit
        for my work.  I want people to know what I wrote.  Can I still get
        credit if I use the GPL?</a></h4>

<dd>
You can certainly get credit for the work.  Part of releasing a
program under the GPL is writing a copyright notice in your own name
(assuming you are the copyright holder).  The GPL requires all copies
to carry an appropriate copyright notice.
<p>

<dt><h4><a HREF="#TOCWhyMustIInclude" NAME="WhyMustIInclude">Why does the GPL
        require including a copy of the GPL with every copy of the program?</a></h4>

<dd>
Including a copy of the license with the work is vital so that
everyone who gets a copy of the program can know what his rights are.
<p>
It might be tempting to include a URL that refers to the license,
instead of the license itself.  But you cannot be sure that the URL
will still be valid, five years or ten years from now.  Twenty years
from now, URLs as we know them today may no longer exist.
<p>
The only way to make sure that people who have copies of the program
will continue to be able to see the license, despite all the changes
that will happen in the network, is to include a copy of the license in
the program.
<p>

<dt><h4><a HREF="#TOCWhatIfWorkIsShort" NAME="WhatIfWorkIsShort">What
        if the work is not much longer than the license itself?</a></h4>

<dd>
If a single program is that short, you may as well use a simple
all-permissive license for it, rather than the GNU GPL.
<p>

<dt><h4><a HREF="#TOCGPLOmitPreamble"
        NAME="GPLOmitPreamble">
        Can I omit the preamble of the GPL, or the instructions
        for how to use it on your own programs, to save space?</a></h4>
<dd>
The preamble and instructions are integral parts of the GNU GPL and
may not be omitted.  In fact, the GPL is copyrighted, and its license
permits only verbatim copying of the entire GPL.  (You can use the
legal terms to make <a HREF="#ModifyGPL">another license</a> but it
won't be the GNU GPL.)
<p>
The preamble and instructions add up to some 5000 characters, less
than 1/3 of the GPL's total size.  They will not make a substantial
fractional change in the size of a software package unless the package
itself is quite small.  In that case, you may as well use a simple
all-permissive license rather than the GNU GPL.
<p>

<dt><h4><a HREF="#TOCWhatIsCompatible" NAME="WhatIsCompatible">What does it
        mean to say that two licenses are "compatible"?</a></h4>

<dd>
In order to combine two programs (or substantial parts of them) into a
larger work, you need to have permission to use both programs in this
way.  If the two programs' licenses permit this, they are compatible.
If there is no way to satisfy both licenses at once, they are
incompatible.
<p>
For some licenses, the way in which the combination is made may affect
whether they are compatible--for instance, they may allow linking two
modules together, but not allow merging their code into one module.
<p>

<dt><h4><a HREF="#TOCWhatDoesCompatMean" NAME="WhatDoesCompatMean">What
does it mean to say a license is "compatible with the GPL".</a></h4>

<dd>
It means that the other license and the GNU GPL are compatible;
you can combine code released under the other license with code
released under the GNU GPL in one larger program.
<p>
The GPL permits such a combination provided it is released under the
GNU GPL.  The other license is compatible with the GPL if it permits
this too.

<p>


<dt><h4><a HREF="#TOCFSWithNFLibs" name="FSWithNFLibs">Can I write
free software that uses non-free libraries?</a></h4>

<dd>
If you do this, your program won't be fully usable in a free
environment. If your program depends on a non-free library to do a
certain job, it cannot do that job in the Free World. If it depends on a
non-free library to run at all, it cannot be part of a free operating
system such as GNU; it is entirely off limits to the Free World.
<p>
So please consider: can you find a way to get the job done without using
this library? Can you write a free replacement for that library?
<p>
If the program is already written using the non-free library, perhaps it
is too late to change the decision. You may as well release the program
as it stands, rather than not release it. But please mention in the
README that the need for the non-free library is a drawback, and suggest
the task of changing the program so that it does the same job without
the non-free library.  Please suggest that anyone who thinks of doing
substantial further work on the program first free it from dependence
on the non-free library.
<p>
Note that there may also be legal issues with combining certain non-free
libraries with GPL-covered Free Software.  Please see <a
href="#GPLIncompatibleLibs">the question on GPL software with
GPL-incompatible libraries</a> for more information.

</dt>


<dt><h4><a HREF="#TOCGPLIncompatibleLibs" name="GPLIncompatibleLibs">What
legal issues come up if I use GPL-incompatible libraries with GPL
software?</a></h4>

<p>
If the libraries that you link with fall within the following exception
in the GPL:
<blockquote>       
     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.
</blockquote>
</p><p>
then you don't have to do anything special to use them; the requirement
to distribute source code for the whole program does not include those
libraries, even if you distribute a linked executable containing them.
Thus, if the libraries you need come with major parts of a proprietary
operating system, the GPL says people can link your program with them
without any conditions.
</p><p>       
If you want your program to link against a library not covered by that
exception, you need to add your own exception, wholly outside of the
GPL. This copyright notice and license notice give permission to link
with the program FOO:

<blockquote>
<p>       
   Copyright (C) yyyy  &lt;name of copyright holder&gt;

</p><p>
    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.
</p><p>
    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.
</p><p>
    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
</p><p>
    In addition, as a special exception, &lt;name of copyright
    holder&gt; gives permission to link the code of this program with
    the FOO library (or with modified versions of FOO that use the
    same license as FOO), and distribute linked combinations including
    the two.  You must obey the GNU General Public License in all
    respects for all of the code used other than FOO.  If you modify
    this file, you may extend this exception to your version of the
    file, but you are not obligated to do so.  If you do not wish to
    do so, delete this exception statement from your version.
</blockquote>
</p><p>

Only the copyright holders for the program can legally authorize this
exception. If you wrote the whole program yourself, then assuming your
employer or school does not claim the copyright, you are the copyright
holder--so you can authorize the exception. But if you want to use parts
of other GPL-covered programs by other authors in your code, you cannot
authorize the exception for them. You have to get the approval of the
copyright holders of those programs.
</p><p>
When other people modify the program, they do not have to make the same
exception for their code--it is their choice whether to do so.
</p><p>
If the libraries you intend to link with are non-free, please also see
<a href="#FSWithNFLibs">the section on writing Free Software which
uses non-free libraries</a>.
</td>

<dt><h4><a HREF="#TOCHowIGetCopyright" NAME="HowIGetCopyright">How do I
  get a copyright on my program in order to release it under the
  GPL?</a></h4>

<dd>
Under the Berne Convention, everything written is automatically
copyrighted from whenever it is put in fixed form.  So you don't have
to do anything to "get" the copyright on what you write--as long as
nobody else can claim to own your work.
<p>
However, registering the copyright in the US is a very good idea.  It
will give you more clout in dealing with an infringer in the US.
<p>

The case when someone else might possibly claim the copyright is if
you are an employee or student; then the employer or the school might
claim you did the job for them and that the copyright belongs to them.
Whether they would have a valid claim would depend on circumstances
such as the laws of the place where you live, and on your employment
contract and what sort of work you do.  It is best to consult a lawyer
if there is any possible doubt.
<p>
If you think that the employer or school might have a claim, you can
resolve the problem clearly by getting a copyright disclaimer signed
by a suitably authorized officer of the company or school.  (Your
immediate boss or a professor is usually NOT authorized to sign such a
disclaimer.)
<p>

<dt><h4><a HREF="#TOCWhatIfSchool" NAME="WhatIfSchool">What if my school
  might want to make my program into its own proprietary software
  product?</a></h4>

<dd>
Many universities nowadays try to raise funds by restricting the use
of the knowledge and information they develop, in effect behaving
little different from commercial businesses.  (See "The Kept
University", Atlantic Monthly, March 2000, for a general discussion of
this problem and its effects.)
<p>
If you see any chance that your school might refuse to allow your
program to be released as free software, it is best to raise the issue
at the earliest possible stage.  The closer the program is to working
usefully, the more temptation the administration might feel to take it
from you and finish it without you.  At an earlier stage, you have
more leverage.
<p>
So we recommend that you approach them when the program is only
half-done, saying, "If you will agree to releasing this as free
software, I will finish it."  Don't think of this as a bluff.  To
prevail, you must have the courage to say, "My program will have
liberty, or never be born."
<p>

<dt><h4><a HREF="#TOCCouldYouHelpApplyGPL" NAME="CouldYouHelpApplyGPL">Could
  you give me step by step instructions on how to apply the GPL to my
  program?</a></h4>

<dd>
See the page of <a HREF="http://www.gnu.org/licenses/gpl-howto.html">
GPL instructions</a>.
<p>

<dt><h4><a HREF="#TOCHeardOtherLicense" NAME="HeardOtherLicense">I heard
  that someone got a copy of a GPL'ed program under another license.  Is
  this possible?</a></h4>

<dd>
The GNU GPL does not give users permission to attach other licenses to
the program.  But the copyright holder for a program can release it
under several different licenses in parallel.  One of them may be the
GNU GPL.
<p>
The license that comes in your copy, assuming it was put in by the
copyright holder and that you got the copy legitimately, is the
license that applies to your copy.
<p>

<dt><h4><a HREF="#TOCReleaseUnderGPLAndNF" NAME="ReleaseUnderGPLAndNF">I
  would like to release a program I wrote under the GNU GPL, but I would
  like to use the same code in non-free programs.</a></h4>

<dd>
To release a non-free program is always ethically tainted, but legally
there is no obstacle to your doing this.  If you are the copyright
holder for the code, you can release it under various different
non-exclusive licenses at various times.
<p>

<dt><h4><a HREF="#TOCDeveloperViolate" NAME="DeveloperViolate">Is the
  developer of a GPL-covered program bound by the GPL?  Could the
  developer's actions ever be a violation of the GPL?</a></h4>

<dd>
Strictly speaking, the GPL is a license from the developer for others
to use, distribute and change the program.  The developer itself is
not bound by it, so no matter what the developer does, this is not
a "violation" of the GPL.
<p>
However, if the developer does something that would violate the GPL if
done by someone else, the developer will surely lose moral standing in
the community.
<p>

<dt><h4><a HREF="#TOCCanDeveloperThirdParty"
  NAME="CanDeveloperThirdParty">Can the developer of a program who
  distributed it under the GPL later license it to another party for
  exclusive use?</a></h4>

<dd>
No, because the public already has the right to use the program under
the GPL, and this right cannot be withdrawn.
<p>

<dt><h4><a HREF="#TOCCanIUseGPLToolsForNF"
  NAME="CanIUseGPLToolsForNF">Can I use GPL-covered editors such as
  GNU Emacs to develop non-free programs?  Can I use GPL-covered tools
  such as GCC to compile them?</a></h4>

<dd>
Yes, because the copyright on the editors and tools does not cover the
code you write.  Using them does not place any restrictions, legally,
on the license you use for your code.
<p>
Some programs copy parts of themselves into the output for technical
reasons--for example, Bison copies a standard parser program into its
output file.  In such cases, the copied text in the output is covered
by the same license that covers it in the source code.  Meanwhile, the
part of the output which is derived from the program's input inherits
the copyright status of the input.
<p>
As it happens, Bison can also be used to develop non-free programs.
This is because we decided to explicitly permit the use of the Bison
standard parser program in Bison output files without restriction.  We
made the decision because there were other tools comparable to Bison
which already permitted use for non-free programs.
<p>

<dt><h4><a HREF="#TOCGPLFairUse" NAME="GPLFairUse">Do I have "fair use"
  rights in using the source code of a GPL-covered program?</a></h4>

<dd>
Yes, you do.  "Fair use" is use that is allowed without any special
permission.  Since you don't need the developers' permission for such
use, you can do it regardless of what the developers said about it--in
the license or elsewhere, whether that license be the GNU GPL or any
other free software license.
<p>
Note, however, that there is no world-wide principle of fair use; what
kinds of use are considered "fair" varies from country to country.
<p>

<dt><h4><a HREF="#TOCGPLUSGov" NAME="GPLUSGov">Can the US Government
    release a program under the GNU GPL?</a></h4>
<dd>
If the program is written by US government employees, it is in the
public domain, which means it is not copyrighted.  Since the GNU GPL
is based on copyright, such a program cannot be released under the GNU
GPL.  (It can still be <a HREF="http://www.gnu.org/philosophy/free-sw.html"> free
software</a>, however; a public domain program is free.)
<p>
However, when a US government agency uses contractors to develop
software, that is a different situation.  The contract can require the
contractor to release it under the GNU GPL.  (GNU Ada was developed in
this way.)  Or the contract can assign the copyright to the government
agency, which can then release the software under the GNU GPL.
<p>

<dt><h4><a HREF="#TOCGPLUSGovAdd" NAME="GPLUSGovAdd">Can the US Government
    release improvements to a GPL-covered program?</a></h4>
<dd>
Yes.  If the improvements are written by US government employees, then
the improvements are in the public domain.  However, the improved
version, as a whole, is still covered by the GNU GPL.  There is no
problem in this situation.
<p>
If the US government uses contractors to do the job, then the
improvements themselves can be GPL-covered.

<p>

<dt><h4><a HREF="#TOCGPLOutput" NAME="GPLOutput">Is there some way that
  I can GPL the output people get from use of my program?  For example,
  if my program is used to develop hardware designs, can I require that
  these designs must be free?</a></h4>

<dd>
In general this is legally impossible; copyright law does not give you
any say in the use of the output people make from their data using
your program.  If the user uses your program to enter or convert his
own data, the copyright on the output belongs to him, not you.  More
generally, when a program translates its input into some other form,
the copyright status of the output inherits that of the input it was
generated from.
<p>
So the only way you have a say in the use of the output is if
substantial parts of the output are copied (more or less) from text in
your program.  For instance, part of the output of Bison (see above)
would be covered by the GNU GPL, if we had not made an exception in
this specific case.
<p>

You could artificially make a program copy certain text into its
output even if there is no technical reason to do so.  But if that
copied text serves no practical purpose, the user could simply delete
that text from the output and use only the rest.  Then he would not
have to obey the conditions on redistribution of the copied text.
<p>

<dt><h4><a HREF="#TOCWhatCaseIsOutputGPL" NAME="WhatCaseIsOutputGPL">In what cases is the output of a GPL program covered by the GPL too?</a></h4>

<dd>
Only when the program copies part of itself into the output.
<p>

<dt><h4><a HREF="#TOCGPLModuleLicense" NAME="GPLModuleLicense">If I add
  a module to a GPL-covered program, do I have to use the GPL as the
  license for my module?</a></h4>

<dd>
The GPL says that the whole combined program has to be released under
the GPL.  So your module has to be available for use under the GPL.
<p>
But you can give additional permission for the use of your code.  You
can, if you wish, release your program under a license which is more
lax than the GPL but compatible with the GPL.  The

<a HREF="http://www.gnu.org/licenses/license-list.html">license
list page</a> gives a partial list of GPL-compatible licenses.
<p>

<dt><h4><a HREF="#TOCIfLibraryIsGPL" NAME="IfLibraryIsGPL">If a library
  is released under the GPL (not the LGPL), does that mean that any
  program which uses it has to be under the GPL?</a></h4>

<dd>
Yes, because the program as it is actually run includes the library.
<p>

<dt><h4><a href="#TOCIfInterpreterIsGPL" name="IfInterpreterIsGPL">If a
  programming language interpreter is released under the GPL, does that
  mean programs written to be interpreted by it must be under
  GPL-compatible licenses?</a></h4>

<dd>
When the interpreter just interprets a language, the answer is no.  The
interpreted program, to the interpreter, is just data; a free software
license like the GPL, based on copyright law, cannot limit what data you
use the interpreter on.  You can run it on any data (interpreted program),
any way you like, and there are no requirements about licensing that data
to anyone.

<p>
However, when the interpreter is extended to provide "bindings" to
other facilities (often, but not necessarily, libraries), the
interpreted program is effectively linked to the facilities it uses
through these bindings.  So if these facilities are released under the
GPL, the interpreted program that uses them must be released in a
GPL-compatible way.  The JNI or Java Native Interface is an example of
such a facility; libraries that are accessed in this way are linked
dynamically with the Java programs that call them.
<p>
Another similar and very common case is to provide libraries with the
interpreter which are themselves interpreted.  For instance, Perl
comes with many Perl modules, and a Java implementation comes with
many Java classes.  These libraries and the programs that call them
are always dynamically linked together.
<p>
A consequence is that if you choose to use GPL'd Perl modules or Java
classes in your program, you must release the program in a
GPL-compatible way, regardless of the license used in the Perl or Java
interpreter that the combined Perl or Java program will run on.
<p>

<dt><h4><a HREF="#TOCWindowsRuntimeAndGPL"
  NAME="WindowsRuntimeAndGPL">I'm writing a Windows application with
  Microsoft Visual C++ (or Visual Basic) and I will be releasing it
  under the GPL.  Is dynamically linking my program with the Visual
  C++ (or Visual Basic) run-time library permitted under the
  GPL?</a></h4>

<dd>
Yes, because that run-time library normally accompanies the compiler
or interpreter you are using.
<p>

<dt><h4><a HREF="#TOCOrigBSD" NAME="OrigBSD">Why is the original BSD
license incompatible with the GPL?</a></h4>

<dd>
Because it imposes a specific requirement that is not in the GPL;
namely, the requirement on advertisements of the program.  The GPL
states:
<p>
<pre>
    You may not impose any further restrictions on the recipients' exercise
    of the rights granted herein.
</pre>
<p>
The advertising clause provides just such a further restriction, and thus is
GPL-incompatible.
<p>
The revised BSD license does not have the advertising clause,
which eliminates the problem.
<p>

<dt><h4><a HREF="#TOCGPLAndPlugins" NAME="GPLAndPlugins">If a program
  released under the GPL uses plug-ins, what are the requirements for
  the licenses of a plug-in.</a></h4>

<dd>
It depends on how the program invokes its plug-ins.  If the program
uses fork and exec to invoke plug-ins, then the plug-ins are separate
programs, so the license for the main program makes no requirements
for them.
<p>
If the program dynamically links plug-ins, and they make function
calls to each other and share data structures, we believe they form a
single program, so plug-ins must be treated as extensions to the main
program.  This means they must be released under the GPL or a
GPL-compatible free software license, and that the terms of the GPL
must be followed when those plug-ins are distributed.

<p>
If the program dynamically links plug-ins, but the communication
between them is limited to invoking the `main' function of the plug-in
with some options and waiting for it to return, that is a borderline
case.
<p>

<dt><h4><a HREF="#TOCGPLPluginsInNF" NAME="GPLPluginsInNF">Can I use the
GPL for a plug-in for a non-free program?</a></h4>

<dd>
If the program uses fork and exec to invoke plug-ins, then the
plug-ins are separate programs, so the license for the main program
makes no requirements for them.  So you can use the GPL for a plug-in,
and there are no special requirements.
<p>
If the program dynamically links plug-ins, and they make function
calls to each other and share data structures, we believe they form a
single program, so plug-ins must be treated as extensions to the main
program.  This means that linking the GPL-covered plug-in with the
main program would violate the GPL.  However, you can resolve that
legal problem by adding an exception to your program's license
which gives permission to link it with the non-free main program.
<p>
For more details, see the question above that starts with, "I am
writing free software that uses a non-free library."

<p>

<dt><h4><a HREF="#TOCLinkingWithGPL" NAME="LinkingWithGPL">You have a
  GPL'ed program that I'd like to link with my code to build a
  proprietary program.  Does the fact that I link with your program mean
  I have to GPL my program?</a></h4>

<dd>
Yes.
<p>

<dt><h4><a HREF="#TOCSwitchToLGPL" NAME="SwitchToLGPL">If so, is there
  any chance I could get a license of your program under the Lesser
  GPL?</a></h4>

<dd>
You can ask, but most authors will stand firm and say no.
The idea of the GPL is that if you want to include our code in your
program, your program must also be free software.  It is supposed
to put pressure on you to release your program in a way that makes
it part of our community.
<p>
You always have the legal alternative of not using our code.
<p>

<dt><h4><a href="#TOCLinkingOverControlledInterface"
  name="LinkingOverControlledInterface">How can I allow linking of
  proprietary modules with my GPL-covered library under a controlled
  interface only?</a></h4>

<dd>
Add this text to the license notice of each file in the package, at
the end of the text that says the file is distributed under the GNU
GPL:
<p>
<pre>
    Linking FOO statically or dynamically with other modules is making a
    combined work based on FOO.  Thus, the terms and conditions of the GNU
    General Public License cover the whole combination.

    As a special exception, the copyright holders of FOO give you
    permission to link FOO with independent modules that communicate with
    FOO solely through the FOOBAR interface, regardless of the license
    terms of these independent modules, and to copy and distribute the
    resulting combined work under terms of your choice, provided that
    every copy of the combined work is accompanied by a complete copy of
    the source code of FOO (the version of FOO used to produce the
    combined work), being distributed under the terms of the GNU General
    Public License plus this exception.  An independent module is a module
    which is not derived from or based on FOO.

    Note that people who make modified versions of FOO are not obligated
    to grant this special exception for their modified versions; it is
    their choice whether to do so.  The GNU General Public License gives
    permission to release a modified version without this exception; this
    exception also makes it possible to release a modified version which
    carries forward this exception.
</pre>
<p>

<dt><h4><a HREF="#TOCManyDifferentLicenses"
  NAME="ManyDifferentLicenses">I have written an application that links
  with many different components, that have different licenses.  I am
  very confused as to what licensing requirements are placed on my
  program.  Can you please tell me what licenses I may use?</a></h4>

<dd>

To answer this question, we would need to see a list of each component
that your program uses, the license of that component, and a brief (a
few sentences for each should suffice) describing how your library
uses that component.  Two examples would be:
<p>
<ul>
<li>To make my software work, it must be linked to the FOO library,
      which is available under the Lesser GPL.
<li>My software makes a system call (with a command line that I built) to
      run the BAR program, which is licensed under "the GPL, with a
      special exception allowing for linking with QUUX".
</ul>
<p>


<dt><h4><a HREF="#TOCMereAggregation" NAME="MereAggregation">What is the
  difference between "mere aggregation" and "combining two modules into
  one program"?</a></h4>

<dd>
Mere aggregation of two programs means putting them side by side on
the same CD-ROM or hard disk.  We use this term in the case where they
are separate programs, not parts of a single program.  In this case,
if one of the programs is covered by the GPL, it has no effect on the
other program.
<p>
Combining two modules means connecting them together so that they form
a single larger program.  If either part is covered by the GPL, the
whole combination must also be released under the GPL--if you can't,
or won't, do that, you may not combine them.
<p>

What constitutes combining two parts into one program?  This is a
legal question, which ultimately judges will decide.  We believe that
a proper criterion depends both on the mechanism of communication
(exec, pipes, rpc, function calls within a shared address space, etc.)
and the semantics of the communication (what kinds of information are
interchanged).
<p>
If the modules are included in the same executable file, they are
definitely combined in one program.  If modules are designed to run
linked together in a shared address space, that almost surely means
combining them into one program.
<p>
By contrast, pipes, sockets and command-line arguments are
communication mechanisms normally used between two separate programs.
So when they are used for communication, the modules normally are
separate programs.  But if the semantics of the communication are
intimate enough, exchanging complex internal data structures, that too
could be a basis to consider the two parts as combined into a larger
program.
<p>

<dt><h4><a HREF="#TOCAssignCopyright" NAME="AssignCopyright">Why does
  the FSF require that contributors to FSF-copyrighted programs assign
  copyright to the FSF?  If I hold copyright on a GPL'ed program, should
  I do this, too?  If so, how?</a></h4>

<dd>
Our lawyers have told us that to be in the <a HREF="http://www.gnu.org/licenses/why-assign.html">best position to enforce
the GPL</a> in court against violators, we should keep the copyright status
of the program as simple as possible.  We do this by asking each contributor
to either assign the copyright on his contribution to the FSF, or disclaim
copyright on it and thus put it in the public domain.
<p>
We also ask individual contributors to get copyright disclaimers from
their employers (if any) so that we can be sure those employers won't
claim to own the contributions.

<p>

Of course, if all the contributors put their code in the public
domain, there is no copyright with which to enforce the GPL.  So we
encourage people to assign copyright on large code contributions, and
only put small changes in the public domain.

<p>

If you want to make an effort to enforce the GPL on your program, it
is probably a good idea for you to follow a similar policy.  Please
contact <a HREF="mailto:hide@address.com">&lt;hide@address.com&gt;</a> if
you want more information.
<p>

<dt><h4><a HREF="#TOCModifyGPL" NAME="ModifyGPL">Can I modify the GPL
    and make a modified license?</a></h4>

<dd>
You can use the GPL terms (possibly modified) in another license
provided that you call your license by another name and do not include
the GPL preamble, and provided you modify the instructions-for-use at
the end enough to make it clearly different in wording and not mention
GNU (though the actual procedure you describe may be similar).

<p>

If you want to use our preamble in a modified license, please write
to <a HREF="mailto:hide@address.com">&lt;hide@address.com&gt;</a>
for permission.  For this purpose we would want to check the actual
license requirements to see if we approve of them.

<p>
Although we will not raise legal objections to your making a modified
license in this way, we hope you will think twice and not do it.  Such
a modified license is almost certainly <a HREF="#WhatIsCompatible">
incompatible with the GNU GPL</a>, and that incompatibility blocks
useful combinations of modules.  The mere proliferation of different
free software licenses is a burden in and of itself.

<p>

<dt><h4><a HREF="#TOCGPLCommercially" NAME="GPLCommercially">If I use a
  piece of software that has been obtained under the GNU GPL, am I
  allowed to modify the original code into a new program, then
  distribute and sell that new program commercially?</a></h4>

<dd>
You are allowed to sell copies of the modified program commercially,
but only under the terms of the GNU GPL.  Thus, for instance, you must
make the source code available to the users of the program as
described in the GPL, and they must be allowed to redistribute and
modify it as described in the GPL.
<p>

These requirements are the condition for including the GPL-covered
code you received in a program of your own.
<p>

<dt><h4><a HREF="#TOCGPLOtherThanSoftware"
NAME="GPLOtherThanSoftware">Can I use the GPL for something other than
software?</a></h4>

<dd>
You can apply the GPL to any kind of work, as long as it is clear what
constitutes the "source code" for the work.  The GPL defines this as
the preferred form of the work for making changes in it.
<p>
However, for manuals and textbooks, or more generally any sort of work
that is meant to teach a subject, we recommend using the GFDL rather
than the GPL.
<p>

<dt><h4><a HREF="#TOCConsider" NAME="Consider">Consider this situation:
<ul>
<li>X releases V1 of a project under the GPL.
<li>Y contributes to the development of V2 with
      changes and new code based on V1.
<li>X wants to convert V2 to a non-GPL license.   

</ul>
Does X need Y's permission?</a></h4>

<dd> 
Yes.  Y was required to release its version under the GNU GPL, as a
consequence of basing it on X's version V1.  Nothing required Y to
agree to any other license for its code.  Therefore, X must get Y's
permission before releasing that code under another license.
<p>

<dt><h4><a HREF="#TOCGPLInProprietarySystem"
  NAME="GPLInProprietarySystem">I'd like to incorporate GPL-covered
  software in my proprietary system.  Can I do this?</a></h4>

<dd>
You cannot incorporate GPL-covered software in a proprietary system.
The goal of the GPL is to grant everyone the freedom to copy,
redistribute, understand, and modify a program.  If you could
incorporate GPL-covered software into a non-free system, it would have
the effect of making the GPL-covered software non-free too.
<p>
A system incorporating a GPL-covered program is an extended version of
that program.  The GPL says that any extended version of the program
must be released under the GPL if it is released at all.  This is for
two reasons: to make sure that users who get the software get the
freedom they should have, and to encourage people to give back
improvements that they make.
<p>

However, in many cases you can distribute the GPL-covered software
alongside your proprietary system.  To do this validly, you must make
sure that the free and non-free programs communicate at arms length,
that they are not combined in a way that would make them
effectively a single program.
<p>
The difference between this and "incorporating" the GPL-covered
software is partly a matter of substance and partly form.  The
substantive part is this: if the two programs are combined so that
they become effectively two parts of one program, then you can't treat
them as two separate programs.  So the GPL has to cover the whole
thing.
<p>
If the two programs remain well separated, like the compiler and the
kernel, or like an editor and a shell, then you can treat them as two
separate programs--but you have to do it properly.  The issue is
simply one of form: how you describe what you are doing.  Why do we
care about this?  Because we want to make sure the users clearly
understand the free status of the GPL-covered software in the
collection.
<p>
If people were to distribute GPL-covered software calling it "part of"
a system that users know is partly proprietary, users might be
uncertain of their rights regarding the GPL-covered software.  But if they
know that what they have received is a free program plus another
program, side by side, their rights will be clear.
<p>

<dt><h4><a HREF="#TOCMoneyGuzzlerInc" NAME="MoneyGuzzlerInc">I'd like to
  modify GPL-covered programs and link them with the portability
  libraries from Money Guzzler Inc.  I cannot distribute the source code
  for these libraries, so any user who wanted to change these versions
  would have to obtained those libraries separately.  Why doesn't the
  GPL permit this?</a></h4>

<dd>
There are two reasons for this.
<p>
First, a general one.  If we permitted company A to make a proprietary
file, and company B to distribute GPL-covered software linked with
that file, the effect would be to make a hole in the GPL big enough to
drive a truck through.  This would be carte blanche for withholding
the source code for all sorts of modifications and extensions to
GPL-covered software.
<p>

Giving all users access to the source code is one of our main goals,
so this consequence is definitely something we want to avoid.
<p>
More concretely, the versions of the programs linked with the Money
Guzzler libraries would not really be free software as we understand
the term--they would not come with full source code that enables users
to change and recompile the program.
<p>

<dt><h4><a href="#TOCGPLIncompatibleAlone" name="GPLIncompatibleAlone">If
license for a module Q has a requirement that's incompatible with the GPL,
but the requirement applies only when Q is distributed by itself, not when
Q is included in a larger program, does that make the license
GPL-compatible?  Can I combine or link Q with a GPL-covered
program?</a></h4>

<dd>
If a program P is released under the GPL that means *any and every part of
it* can be used under the GPL.  If you integrate module Q, and release the
combined program P+Q under the GPL, that means any part of P+Q can be used
under the GPL.  One part of P+Q is Q.  So releasing P+Q under the GPL says
that Q any part of it can be used under the GPL.  Putting it in other
words, a user who obtains P+Q under the GPL can delete P, so that just Q
remains, still under the GPL.
<p>
If the license of module Q permits you to give permission for that,
then it is GPL-compatible.  Otherwise, it is not GPL-compatible.
<p>
If the license for Q says in no uncertain terms that you must do certain
things (not compatible with the GPL) when you redistribute Q on its own,
then it does not permit you to distribute Q under the GPL.  It follows that
you can't release P+Q under the GPL either.  So you cannot link or combine
P with Q.
<p>

<dt><h4><a HREF="#TOCModifiedJustBinary"
  NAME="ModifiedJustBinary">Can I release a modified
    version of a GPL-covered program in binary form only?</a></h4>

<dd>
No.  The whole point of the GPL is that all modified versions
must be <a HREF="http://www.gnu.org/philosophy/free-sw.html">
free software</a>--which means, in particular, that the source
code of the modified version is available to the users.
<p>

<dt><h4><a HREF="#TOCDistributeWithSourceOnInternet"
  NAME="DistributeWithSourceOnInternet">I want to distribute
  binaries without accompanying sources.  Can I provide source code by
  FTP instead of by mail order?</a></h4>

<dd>
You're supposed to provide the source code by mail-order on a physical
medium, if someone orders it.  You are welcome to offer people a way
to copy the corresponding source code by FTP, in addition to the
mail-order option, but FTP access to the source is not sufficient to
satisfy section 3 of the GPL.
<p>
When a user orders the source, you have to make sure to get the source
to that user.  If a particular user can conveniently get the source
from you by anonymous FTP, fine--that does the job.  But not every
user can do such a download.  The rest of the users are just as
entitled to get the source code from you, which means you must be
prepared to send it to them by post.
<p>
If the FTP access is convenient enough, perhaps no one will choose to
mail-order a copy.  If so, you will never have to ship one.  But you
cannot assume that.
<p>

Of course, it's easiest to just send the source with the binary in the
first place.
<p>

<dt><h4><a HREF="#TOCRedistributedBinariesGetSource"
    NAME="RedistributedBinariesGetSource">My friend got a GPL-covered
    binary with an offer to supply source, and made a copy for me.
    Can I use the offer myself to obtain the source?</a></h4>

<dd>
Yes, you can.  The offer must be open to everyone who has a copy
of the binary that it accompanies.  This is why the GPL says your
friend must give you a copy of the offer along with a copy of the
binary---so you can take advantage of it.
<p>

<dt><h4><a HREF="#TOCSourceAndBinaryOnDifferentSites"
  NAME="SourceAndBinaryOnDifferentSites">Can I put the binaries on my
  Internet server and put the source on a different Internet
  site?</a></h4>

<dd>
The GPL says you must offer access to copy the source code "from the
same place"; that is, next to the binaries.  However, if you make
arrangements with another site to keep the necessary source code
available, and put a link or cross-reference to the source code next
to the binaries, we think that qualifies as "from the same place".
<p>
Note, however, that it is not enough to find some site that happens to
have the appropriate source code today, and tell people to look there.
Tomorrow that site may have deleted that source code, or simply
replaced it with a newer version of the same program.  Then you would
no longer be complying with the GPL requirements.  To make a
reasonable effort to comply, you need to make a positive arrangement
with the other site, and thus ensure that the source will be available
there for as long as you keep the binaries available.

<p>

<dt><h4><a HREF="#TOCDistributeExtendedBinary"
  NAME="DistributeExtendedBinary">I want to distribute an extended
  version of a GPL-covered program in binary form.  Is it enough to
  distribute the source for the original version?</a></h4>

<dd>
No, you must supply the source code that corresponds to the binary.
Corresponding source means the source from which users can rebuild the
same binary.
<p>
Part of the idea of free software is that users should have access to
the source code for *the programs they use*.  Those using your version
should have access to the source code for your version.
<p>
A major goal of the GPL is to build up the Free World by making sure
that improvement to a free program are themselves free.  If you
release an improved version of a GPL-covered program, you must release
the improved source code under the GPL.
<p>

<dt><h4><a HREF="#TOCDistributingSourceIsInconvenient"
  NAME="DistributingSourceIsInconvenient">I want to distribute
  binaries, but distributing complete source is inconvenient.  Is it
  ok if I give users the diffs from the "standard" version along with the
  binaries?</a></h4>

<dd>

This is a well-meaning request, but this method of providing the
source doesn't really do the job.
<p>
A user that wants the source a year from now may be unable to get the
proper version from another site at that time.  The standard
distribution site may have a newer version, but the same diffs
probably won't work with that version.
<p>
So you need to provide complete sources, not just diffs, with
the binaries.
<p>

<dt><h4><a HREF="#TOCAnonFTPAndSendSource"
  NAME="AnonFTPAndSendSources">I want to make binaries available for
  anonymous FTP, but send sources only to people who order them.</a></h4>

<dd>
If you want to distribute binaries by anonymous FTP, you have to
distribute sources along with them.  This should not be hard.  If you
can find a site to distribute your program, you can surely find one
that has room for the sources.
<p>
The sources you provide must correspond exactly to the binaries.
In particular, you must make sure they are for the same version of
the program--not an older version and not a newer version.
<p>
You can make the sources and binaries available on different machines,
provided they are equally easy to get to, and provided that you have
information next to the binaries saying where to find the sources.
<p>

<dt><h4><a HREF="#TOCHowCanIMakeSureEachDownloadGetsSource"
  NAME="HowCanIMakeSureEachDownloadGetsSource">How can I make sure each
  user who downloads the binaries also gets the source?</a></h4>

<dd>
You don't have to make sure of this.  As long as you make the source
and binaries available so that the users can see what's available and
take what they want, you have done what is required of you.  It is up
to the user whether to download the source.
<p>
Our requirements for redistributors are intended to make sure the
users can get the source code, not to force users to download the
source code even if they don't want it.
<p>

<dt><h4><a HREF="#TOCUnreleasedMods" NAME="UnreleasedMods">A company
    is running a modified version of a GPL'ed program on a web site.
    Does the GPL say they must release their modified
    sources?</a></h4>

<dd>
The GPL permits anyone to make a modified version and use it without
ever distributing it to others.  What this company is doing is a
special case of that.  Therefore, the company does not have to release
the modified sources.
<p>
It is essential for people to have the freedom to make modifications
and use them privately, without ever publishing those modifications.
However, putting the program on a server machine for the public to
talk to is hardly "private" use, so it would be legitimate to require
release of the source code in that special case.  We are thinking
about doing something like this in GPL version 3, but we don't have
precise wording in mind yet.

<p>
In the mean time, you might want to use the <a
HREF="http://www.affero.org/oagpl.html">Affero GPL</a> for programs
designed for network server use.
<p>
</dd>

<dt><h4><a HREF="#TOCInternalDistribution"
    NAME="InternalDistribution">Is making and using multiple copies
    within one organization or company "distribution"?</a></h4>

<dd>
No, in that case the organization is just making the copies for
itself.  As a consequence, a company or other organization can develop
a modified version and install that version through its own
facilities, without giving the staff permission to release that
modified version to outsiders.
<p>

However, when the organization transfers copies to other organizations
or individuals, that is distribution.  In particular, providing copies
to contractors for use off-site is distribution.
<p>


<dt><h4><a HREF="#TOCStolenCopy" NAME="StolenCopy"> If someone steals
    a CD containing a version of a GPL-covered program, does the GPL
    give him the right to redistribute that version?</a></h4>

<dd>
If the version has been released elsewhere, then the thief probably
does have the right to make copies and redistribute them under the GPL,
but if he is imprisoned for stealing the CD he may have to wait until
his release before doing so.
<p>
If the version in question is unpublished and considered by a company
to be its trade secret, then publishing it may be a violation of trade
secret law, depending on other circumstances.  The GPL does not change
that.  If the company tried to release its version and still treat it
as a trade secret, that would violate the GPL, but if the company
hasn't released this version, no such violation has occurred.
<p>

<dt><h4><a HREF="#TOCTradeSecretRelease"
    NAME="TradeSecretRelease">What if a company distributes a copy as
    a trade secret?</a></h4>
<dd>
If a company distributes a copy to you and claims it is a trade
secret, the company has violated the GPL and will have to cease
distribution.  Note how this differs from the theft case above; the
company does not intentionally distribute a copy when a copy is
stolen, so in that case the company has not violated the GPL.
<p>

<dt><h4><a HREF="#TOCWhySomeGPLAndNotLGPL"
  NAME="WhySomeGPLAndNotLGPL">Why are some GNU libraries released under
  the ordinary GPL rather than the Lesser GPL?</a></h4>

<dd>
Using the Lesser GPL for any particular library constitutes a retreat
for free software.  It means we partially abandon the attempt to
defend the users' freedom, and some of the requirements to share what
is built on top of GPL-covered software.  In themselves, those are
changes for the worse.
<p>
Sometimes a localized retreat is a good strategy.  Sometimes, using
the LGPL for a library might lead to wider use of that library, and
thus to more improvement for it, wider support for free software, and
so on.  This could be good for free software if it happens to a large
extent.  But how much will this happen?  We can only speculate.
<p>
It would be nice to try out the LGPL on each library for a while, see
whether it helps, and change back to the GPL if the LGPL didn't help.
But this is not feasible.  Once we use the LGPL for a particular
library, changing back would be difficult.
<p>
So we decide which license to use for each library on a case-by-case
basis.  There is a <a HREF="http://www.gnu.org/licenses/why-not-lgpl.html">
long explanation</a> of how we judge the question.
<p>

<dt><h4><a HREF="#TOCWillYouMakeAnException"
  NAME="WillYouMakeAnException">Using a certain GNU program under the
  GPL does not fit our project to make proprietary software.  Will you
  make an exception for us?  It would mean more users of that
  program.</a></h4>

<dd>
Sorry, we don't make such exceptions.  It would not be right.
<p>
Maximizing the number of users is not our aim.  Rather, we are trying
to give the crucial freedoms to as many users as possible.  In
general, proprietary software projects hinder rather than help the
cause of freedom.
<p>
We do occasionally make license exceptions to assist a project which
is producing free software under a license other than the GPL.
However, we have to see a good reason why this will advance the cause
of free software.
<p>
We also do sometimes change the distribution terms of a package, when
that seems clearly the right way to serve the cause of free software;
but we are very cautious about this, so you will have to show us very
convincing reasons.
<p>

<dt><h4><a HREF="#TOCVersionTwoOrLater" NAME="VersionTwoOrLater">Why
should programs say "Version 2 of the GPL or any later version"?</a></h4>

<dd>
From time to time, at intervals of years, we change the GPL--sometimes
to clarify it, sometimes to permit certain kinds of use not previously
permitted, and sometimes to tighten up a requirement.  (The last
change was in 1991.)  Using this "indirect pointer" in each program
makes it possible for us to change the distribution terms on the
entire collection of GNU software, when we update the GPL.
<p>
If each program lacked the indirect pointer, we would be forced to
discuss the change at length with numerous copyright holders, which
would be a virtual impossibility.  In practice, the chance of having
uniform distribution terms for GNU software would be nil.
<p>
Suppose a program says "Version 2 of the GPL or any later version" and
a new version of the GPL is released.  If the new GPL version gives
additional permission, that permission will be available immediately
to all the users of the program.  But if the new GPL version has a
tighter requirement, it will not restrict use of the current version
of the program, because it can still be used under GPL version 2.
When a program says "Version 2 of the GPL or any later version", users
will always be permitted to use it, and even change it, according to
the terms of GPL version 2--even after later versions of the GPL are
available.
<p>
If a tighter requirement in a new version of the GPL need not be
obeyed for existing software, how is it useful?  Once GPL version 3 is
available, the developers of most GPL-covered programs will release
subsequent versions of their programs specifying "Version 3 of the GPL
or any later version".  Then users will have to follow the tighter
requirements in GPL version 3, for subsequent versions of the program.
<p>
However, developers are not obligated to do this; developers can
continue allowing use of the previous version of the GPL, if that is
their preference.
<p>

<dt><h4><a HREF="#TOCWhyNotGPLForManuals" NAME="WhyNotGPLForManuals">Why
don't you use the GPL for manuals?</a></h4>

<dd>
It is possible to use the GPL for a manual, but the GNU Free
Documentation License (GFDL) is much better for manuals.

<p>
The GPL was designed for programs; it contains lots of complex clauses
that are crucial for programs, but that would be cumbersome and
unnecessary for a book or manual.  For instance, anyone publishing the
book on paper would have to either include machine-readable "source
code" of the book along with each printed copy, or provide a written
offer to send the "source code" later.
<p>
Meanwhile, the GFDL has clauses that help publishers of free manuals
make a profit from selling copies--cover texts, for instance.  The
special rules for Endorsements sections make it possible to use the
GFDL for an official standard.  This would permit modified versions,
but they could not be labeled as "the standard".
<p>
Using the GFDL, we permit changes in the text of a manual that covers
its technical topic.  It is important to be able to change the
technical parts, because people who change a program ought to change
the documentation to correspond.  The freedom to do this is an
ethical imperative.
<p>
Our manuals also include sections that state our political position
about free software.  We mark these as "invariant", so that they
cannot be changed or removed.  The GFDL makes provisions for these
"invariant sections".
<p>

<dt><h4><a HREF="#TOCGPLTranslations" NAME="GPLTranslations">Are there
translations of the GPL into other languages?</a></h4>

<dd>
It would be useful to have translations of the GPL into languages
other than English.  People have even written translations and sent
them to us.  But we have not dared to approve them as officially
valid.  That carries a risk so great we do not dare accept it.
<p>
A legal document is in some ways like a program.  Translating it is
like translating a program from one language and operating system to
another.  Only a lawyer skilled in both languages can do it--and even
then, there is a risk of introducing a bug.

<p>
If we were to approve, officially, a translation of the GPL, we would
be giving everyone permission to do whatever the translation says they
can do.  If it is a completely accurate translation, that is fine.
But if there is an error in the translation, the results could be a
disaster which we could not fix.
<p>
If a program has a bug, we can release a new version, and eventually
the old version will more or less disappear.  But once we have given
everyone permission to act according to a particular translation, we
have no way of taking back that permission if we find, later on, that
it had a bug.
<p>
Helpful people sometimes offer to do the work of translation for us.
If the problem were a matter of finding someone to do the work, this
would solve it.  But the actual problem is the risk of error, and
offering to do the work does not avoid the risk.  We could not
possibly authorize a translation written by a non-lawyer.
<p>
Therefore, for the time being, we are not approving translations
of the GPL as globally valid and binding.  Instead, we are doing two
things:
<p>
<ul>
<li> Referring people to unofficial translations.
<p>
This means that we permit people to write translations of the GPL, but
we don't approve them as legally valid and binding.
<p>
An unapproved translation has no legal force, and it should say so
explicitly.  It should be marked as follows:
<p>

<pre>
    This translation of the GPL is informal, and not officially approved
    by the Free Software Foundation as valid.  To be completely sure of
    what is permitted, refer to the original GPL (in English).
</pre>
<p>
But the unapproved translation can serve as a hint for how to
understand the English GPL.  For many users, that is sufficient.
<p>
However, businesses using GNU software in commercial activity, and
people doing public ftp distribution, should need to check the real
English GPL to make sure of what it permits.
<p>
<li>
Publishing translations valid for a single country only.
<p>
We are considering the idea of publishing translations which are
officially valid only for one country.  This way, if there is a
mistake, it will be limited to that country, and the damage will not
be too great.
<p>
It will still take considerable expertise and effort from a sympathetic
and capable lawyer to make a translation, so we cannot promise any
such translations soon.
</ul>

<dt><h4><a HREF="#TOCInterpreterIncompat" NAME="InterpreterIncompat">If
a programming language interpreter has a license that is incompatible
with the GPL, can I run GPL-covered programs on it?</a></h4>

<dd>

When the interpreter just interprets a language, the answer is yes.
The interpreted program, to the interpreter, is just data; the GPL
doesn't restrict what tools you process the program with.

However, when the interpreter is extended to provide "bindings" to
other facilities (often, but not necessarily, libraries), the
interpreted program is effectively linked to the facilities it uses
through these bindings.  The JNI or Java Native Interface is an
example of such a facility; libraries that are accessed in this way
are linked dynamically with the Java programs that call them.

So if these facilities are released under a GPL-incompatible license,
the situation is like linking in any other way with a GPL-incompatible
library.  Which implies that:

<ol>
  <li>If you are writing code and releasing it under the GPL, you can
  state an explicit exception giving permission to link it with those
  GPL-incompatible facilities.<p>

  <li>If you wrote and released the program under the GPL, and you
  designed it specifically to work with those facilities, people can
  take that as an implicit exception permitting them to link it with
  those facilities.  But if that is what you intend, it is better
  to say so explicitly.<p>

  <li>You can't take someone else's GPL-covered code and use it that
  way, or add such exceptions to it.  Only the copyright holders of that
  code can add the exception.

</ol>

<dt><h4><a HREF="#TOCWhoHasThePower" NAME="WhoHasThePower">Who has the
power to enforce the GPL?</a></h4>

<dd>

Since the GPL is a copyright license, the copyright holders of the
software are the ones who have the power to enforce the GPL.  If you
see a violation of the GPL, you should inform the developers of the
GPL-covered software involved.  They either are the copyright holders,
or are connected with the copyright holders.  <a
href="http://www.fsf.org/licenses/gpl-faq.html#ReportingViolation">Learn
more about reporting GPL violations.</a>

<dt><h4><a HREF="#TOCOOPLang" NAME="OOPLang"> In an object-oriented
language such as Java, if I use a class that is GPL'ed without
modifying, and subclass it, in what way does the GPL affect the larger
program?</a></h4>

<dd>
Subclassing is creating a derivative work.  Therefore, the terms of the
GPL affect the whole program where you create a subclass of a GPL'ed
class.


<dt><h4><a HREF="#TOCPortProgramToGL" NAME="PortProgramToGL">If I port
my program to GNU/Linux, does that mean I have to release it as Free
Software under the GPL or some other Free Software license?</a></h4>

<dd>

In general, the answer is no--this is not a legal requirement.  In
specific, the answer depends on which libraries you want to use and what
their licenses are.  Most system libraries either use the <a
HREF="http://www.gnu.org/copyleft/lesser.html">GNU Lesser GPL</a>, or use the GNU GPL plus an
exception permitting linking the library with anything.  These libraries
can be used in non-free programs; but in the case of the Lesser GPL, it
does have some requirements you must follow.

<p>

Some libraries are released under the GNU GPL alone; you must use a
GPL-compatible license to use those libraries.  But these are normally
the more specialized libraries, and you would not have had anything much
like them on another platform, so you probably won't find yourself
wanting to use these libraries for simple porting.

<p>

Of course, your software is not a contribution to our community if it is
not free, and people who value their freedom will refuse to use it.
Only people willing to give up their freedom will use your software,
which means that it will effectively function as an inducement for people
to lose their freedom.

<p>

If you hope some day to look back on your career and feel that
it has contributed to the growth of a good and free society, you
need to make your software free.


<dt><h4><a HREF="#TOCCompanyGPLCostsMoney" NAME="CompanyGPLCostsMoney">
I just found out that a company has a copy of a GPL'ed program, and it
costs money to get it.  Aren't they violating the GPL by not making it
available on the Internet?</a></h4>

<dd>

No.  The GPL does not require anyone to use the Internet for
distribution.  It also does not require anyone in particular to
redistribute the program.  And (outside of one special case), even if
someone does decide to redistribute the program sometimes, the GPL
doesn't say he has to distribute a copy to you in particular, or any
other person in particular.
<p>
What the GPL requires is that he must have the freedom to distribute a
copy to you <em>if he wishes to</em>.  Once the copyright holder does
distribute a copy program to someone, that someone can then redistribute
the program to you, or to anyone else, as he sees fit.
<p>

<dt><h4><a HREF="#TOCReleaseNotOriginal" NAME="ReleaseNotOriginal"> Can
I release a program with a license which says that you can distribute
modified versions of it under the GPL but you can't distribute the
original itself under the GPL?</a></h4>

<dd>

No.  Such a license would be self-contradictory.  Let's look at its 
implications for me as a user. 
<p>
Suppose I start with the original version (call it version A), add 
some code (let's imagine it is 1000 lines), and release that modified 
version (call it B) under the GPL.  The GPL says anyone can change 
version B again and release the result under the GPL.  So I (or 
someone else) can delete those 1000 lines, producing version C which 
has the same code as version A but is under the GPL. 
<p>
If you try to block that path, by saying explicitly in the license that 
I'm not allowed to reproduce something identical to version A under 
the GPL by deleting those lines from version B, in effect the license 
now says that I can't fully use version B in all the ways that the GPL 
permits.  In other words, the license does not in fact allow a user to 
release a modified version such as B under the GPL. 
<p>

</body></html>
Return current item: CodeTrack: Web-based Bug Tracking