guide/GPL-Business/gpl-business.tex

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%      Tutorial Text for the GPL for Businesspeople and Developers course
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% Copyright (C) 2003 Free Software Foundation, Inc.

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\begin{document}

\begin{titlepage}

{\Large

\begin{center}

\vspace{.5in}

{\sc The GNU General Public License for Businesspeople and Developers } \\

\vspace{1in}

A Tutorial By:

\vspace{.3in}
Bradley M. Kuhn

Executive Director

Free Software Foundation


\end{center}
}

\vfill

{\parindent 0in
Copyright \copyright{} 2003 \hspace{.2in} Free Software Foundation, Inc.

\vspace{.3in}

Verbatim copying and distribution of this entire document is permitted in
any medium, provided this notice is preserved.
}

\end{titlepage}

\begin{abstract}

This tutorial gives a section-by-section explanation of the most popular
Free Software copyright license, the GNU General Public License (GNU GPL),
and teaches software developers, managers and businesspeople how to use
the GPL and GPL'ed software successfully in new Free Software business and
in existing, successful enterprises.

Attendees should have a general familiarity with software development
processes.  A vague understanding of how copyright law applies to software
is also helpful.  The tutorial is of most interest to software developers
and managers who run software businesses that modify and/or redistribute
software under terms of the GNU GPL (or who wish to do so in the future),
and those who wish to make use of existing GPL'ed software in their
enterprise.

This tutorial introduces the GNU GPL and its terms to professionals who
are not well versed in the details of copyright law.  Presented by a
software developer and manager, this tutorial informs those who wish to
have a deeper understanding of how the GNU GPL uses copyright law to
protect software freedom and to assist in the formation of Free Software
businesses, and of the organizatinoal motivations behind the GNU GPL.

Upon completion of the tutorial, successful attendees can expect to have
learned the following:

\begin{itemize}

  \item the freedom-defending purpose of each term of the GNU GPL.

  \item the redistribution options under the GPL.

  \item the obligations when modifying GPL'ed software.

  \item how to properly apply the GPL to a new software.

  \item how to build a plan for proper and successful compliance with the GPL.

  \item the business advantages that the GPL provides.

  \item the most common business models used in conjunction with the GPL.

  \item how existing GPL'ed software can be used in existing enterprises.
\end{itemize}

\end{abstract}

\chapter{What Is Free Software?}

Consideration of the GNU General Public License (herein, abbreviated as
``GNU GPL'' or just ``GPL'') must begin by first considering the broader
world of ``Free Software''.  The GPL was not created from a void, rather,
it was created to embody and defend a set of principles that were set
forth at the founding of the GNU project and the Free Software Foundation
(FSF)---the organization that upholds, defends and promotes the philosophy
of software freedom.  A prerequisite for understanding the GPL and its
terms and conditions is a basic understanding of the principles behind it.
The GPL is unlike almost all other software licenses in that it is
designed to defend and uphold these principles.

\section{The Free Software Definition}

The Free Software Definition is set forth in full on FSF's website at
\href{http://www.fsf.org/philosophy/free-sw.html}{http://www.fsf.org/philosophy/free-sw.html}.
This section presents an abbreviated version that will focus on the parts
that are most pertinent to the terms of the GPL\@.

A particular program is Free Software if it grants a particular user of
that program, the following freedoms:

\begin{itemize}

\item the freedom to run the program for any purpose.

\item the freedom to change and modify the program.

\item the freedom to copy and share the program.

\item the freedom to share improved versions of the program.

\end{itemize}

The focus on ``a particular user'' is very pertinent here.  It is not
uncommon for the same version of a specific program to grant these
freedoms to some subset of its user base, while others have none or only
some of these freedoms.  Section~\ref{relicensing} talks in detail about
how this can happen even if a program is released under the GPL\@.

Some people refer to software that gives these freedoms as ``Open
Source''.  Besides having a different political focus than those who call
it Free Software\footnote{The political differences between the Free
Software Movement and the Open Source Movement are documented on FSF's
website at
\href{http://www.fsf.org/philosophy/free-software-for-freedom.html}
{http://www.gnu.org/philosophy/free-software-for-freedom.html}.},
those who call the software ``Open Source'' are focused on a side issue.
User access to the source code of a program is a prerequisite to make use
of the freedom to modify.  However, the important issue is what freedoms
are granted in the license of that source code.  Microsoft's ``Shared
Source'' program, for example, gives various types of access to source
code, but almost none of the freedoms described in this section.

One key issue that is central to these freedoms is that there are no
restrictions on how these freedoms can be excercised.  Specifically, users
and programmers can exercise these freedoms non-commercially or
commercially.  Licenses that grant these freedoms for non-commercial
activies but prohibit them for commercial activites are considered
non-Free.

In general, software for which most or all of these freedoms are
restricted in any way is called ``non-Free Software''.  Typically, the
term ``proprietary software'' is used more or less interchangably with
``non-Free Software''.  Personally, I tend to use the term ``non-Free
Software'' to refer to non-commercial software that restricts freedom
(such as ``shareware'') and ``propreitary software'' to refer to
commercial software that restricts freedom (such as nearly all of
Microsoft's and Oracle's offerings).

The remainder of this section considers each of the four freedoms in
detail.

\subsection{The Freedom to Run}

For a program to be Free Software, the freedom to run the program must be
completely unrestricted.  This means that any use for that software that
the user can come up with must be permitted.  Perhaps, for example, the
user has discovered an innovative new use for a particular program, one
that the programmer never could have predicted.  Such a use much not be
restricted.

It was once rare that this freedom was restricted by even proprietary
software; today it is not so rare.  Most End User Licensing Agreements
(EULAs) that cover most proprietary software restrict some types of use.
For example, some versions of Microsoft's Frontpage software prohbit use
of the software to create websites that generate negative publicity for
Microsoft.  Free Software has no such restrictions; everyone is free to
use Free Software for any purpose whatsoever.

\subsection{The Freedom to Change and Modify}

Free Software programs allow users to change, modify and adapt the
software to suit their needs.  Access to the source code and related build
scripts are an essential part of this freedom.  Without the source code
and the ability to build the binary applications from that source, the
freedom cannot be properly exercised.

Programmers can take direct benefit from this freedom, and often do.
However, this freedom is essential to users who are not programmers.
Users must have the right to engage in a non-commercial enviornment of
finding help with the software (as often happens on email lists and in
users groups).  This means they must have the freedom to recruit
programmers who might altrusitcally assist them to modify their software.

The commercial exercise of this freedom is also essential.  Each user, or
group of users, must have the right to hire anyone they wish on a
competitive free market to modify and change the software.  This means
that companies have a right to hire anyone they wish to modify their Free
Software.  Additionally, such companies may contract with other companies
to commission software modification.

\subsection{The Freedom to Copy and Share}

Users may share Free Software in a variety of ways.  Free Software
advocates work to eliminate fundamental ethical delimema of the software
age: choosing between obeying a software license, and friendship (by
giving away a copy of a program your friend who likes the software you are
using).  Free Software licenses, therefore, must permit this sort of
altruistic sharing of software amoung friends.

The commercial enviornment must also have the benefits of this freedom.
Commercial sharing typically takes the form of selling copies of Free
Software.  Free Software can be sold at any price to anyone.  Those who
redistribute Free Software commercially have the freedom to selectively
distribute (you can pick your customers) and to set prices at any level
the redistributor sees fit.

It is true that many people get copies of Free Software very cheaply (and
sometimes without charge). The competitive free market of Free Software
tends to keep prices low and reasonable.  However, if someone is willing
to pay a billion dollars for one copy of the GNU Compiler Collection, such
a sale is completely permited.

Another common instance of commercial sharing is service-oriented
distribution.  For example, a distribution vendor may provide immediate
security and upgrade distribution via a special network service.  Such
distribution is completely permitted for Free Software.

\subsection{The Freedom to Share Improvements}

The freedom to modify and improve is somewhat empty without the freedom to
share those improvements.  The Free Software community is built on the
pillar of altruistic sharing of improved Free Software.  Inevitably, a
Free Software project sprouts a mailing list where improvements are shared
freely among members of the development community.  Such non-commercial
sharing must be permitted for Free Software to thrive.

Commercial sharing of modified Free Software is equally important.  For a
competitive free market for support to exist, all developers --- from
single-person contractors to large software companies --- must have the
freedom to market their services as improvers of Free Software.  All forms
of such service marketing must be equally available to all.

For example, selling support services for Free Software is fully
permitted.  Companies and individuals can offer thesmelves as ``the place
to call'' when software fails or does not function properly.  For such a
service to be meaningful, the entity offering that service must have the
right to modify and improve the software for the customer to correct any
problems that are beyond mere user error.

Entities must also be permitted to make available modified versions of
Free Software.  Most Free Software programs have a so-called ``canonoical
version'' that is made available from the primary developers of the
software.  Hoewver, all who have the software have the ``freedom to fork''
--- that is, make available non-trivial modified versions of the software
on a permenant or semi-permenant basis.  Such freedom is central to
vibrant developer and user interaction.

Companies and individuals have the right to make true value-added versions
of Free Software.  They may use freedom to share improvements to
distribute distinct versions of Free Software with different functionality
and features.  Furthermore, this freedom can be exercised to serve a
disenfranchised subset of the user community.  If the developers of the
canonical version refuse to serve the needs of some of the software's
users, other entities have the right to create long- or short-lived fork
that serves that sub-community.

\section{How Does Software Become Free?}


\appendix

\chapter{The GNU General Public License}

\begin{center}
{\parindent 0in

Version 2, June 1991

Copyright \copyright\ 1989, 1991 Free Software Foundation, Inc.

\bigskip

59 Temple Place - Suite 330, Boston, MA  02111-1307, USA

\bigskip

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

\begin{center}
{\bf\large Preamble}
\end{center}


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

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

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

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

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

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

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

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

\begin{center}
{\Large \sc Terms and Conditions For Copying, Distribution and
  Modification}
\end{center}


%\renewcommand{\theenumi}{\alpha{enumi}}
\begin{enumerate}

\addtocounter{enumi}{-1}

\item 

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

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

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

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

\item

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

\begin{enumerate}

\item 

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

\item

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

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

\end{enumerate}


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

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

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

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

\begin{enumerate}

\item

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

\item

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

\item

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

\end{enumerate}


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

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

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

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

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

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

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

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

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

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

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

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

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

\begin{center}
{\Large\sc
No Warranty
}
\end{center}

\item
{\sc Because the program is licensed free of charge, there is no warranty
for the program, to the extent permitted by applicable law.  Except when
otherwise stated in writing the copyright holders and/or other parties
provide the program ``as is'' without warranty of any kind, either expressed
or implied, including, but not limited to, the implied warranties of
merchantability and fitness for a particular purpose.  The entire risk as
to the quality and performance of the program is with you.  Should the
program prove defective, you assume the cost of all necessary servicing,
repair or correction.}

\item
{\sc In no event unless required by applicable law or agreed to in writing
will any copyright holder, or any other party who may modify and/or
redistribute the program as permitted above, be liable to you for damages,
including any general, special, incidental or consequential damages arising
out of the use or inability to use the program (including but not limited
to loss of data or data being rendered inaccurate or losses sustained by
you or third parties or a failure of the program to operate with any other
programs), even if such holder or other party has been advised of the
possibility of such damages.}

\end{enumerate}


\begin{center}
{\Large\sc End of Terms and Conditions}
\end{center}


\pagebreak[2]

\section*{Appendix: How to Apply These Terms to Your New Programs}

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

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

\begin{quote}
one line to give the program's name and a brief idea of what it does. \\
Copyright (C) yyyy  name of author \\

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

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

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

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

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

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


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

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

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

signature of Ty Coon, 1 April 1989 \\
Ty Coon, President of Vice
\end{quote}


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

\end{document}