%    http://www.ctan.org/pkg/memoir

%   http://mirror.unl.edu/ctan/macros/latex/contrib/memoir/memman.pdf

% For the moment, I've thrown in fancychap because I don't have time to

% research memoir.

% FIXME: Some overall formatting hacks that would really help:

%   * I have started using  \hyperref[LABEL]{text} extensively, which seems

%     to work great in the PDF and HTML versions, but in the Postscript

%     version, the link lost entirely.  I think we need an additional command

%     to replace \hyperref which takes an optional third argument that will

%     insert additional text only when generating print versions, such as:

%      \newhyperref[GPLv2s3]{the requirements for binary distribution under

%      GPLv2}{(see section~\ref*{GPLv2s3} for more information)}

%

%     This is a careful balance, because it'd be all too easy to over-pepper

%     the printed version with back/forward references, but there are

%     probably times when this is useful.

%   * Similar issue: \href{} is well known not to carry the URLs in the print

%     versions.  Adding a footnote with the URL for the print version is

%     probably right.  (or maybe a References page?)

%   * The text is extremely inconsistent regarding formatting of code and

%     commands.  The following varied different methods have been used:

%         + the \verb%..% inline form

%         + verbatim environment (i.e., \begin{verbatim}

%         + {\tt }

%         + \texttt{}

%         + the lstlisting environment (i.e., \begin{lstlisting}

%     These should be made consistent, using only two forms: one for line and

%     one for a long quoted section.

% FIXME: s/GPL enforcers/COGEOs/g

%        (the term coined later but not used throughout) This can't be done

%        by rote, since it may not be appropriate everywhere and shouldn't be

%        used *before* it's coined in the early portions of

%        compliance-guide.tex (and it's probably difficult to coin it earlier

%        anyway).  BTW, I admit COGEOs isn't the best acronym, but I started

%        with ``Community Enforcement Organizations'', which makes CEO, which

%        is worse. :)  My other opting was   COEO, which seemed too close to

%        CEO.  Suggestions welcome.

\usepackage{listings}

\usepackage{enumerate}

\usepackage{enumitem}

\usepackage[Conny]{fncychap}

\usepackage[dvips]{graphicx}

\usepackage[verbose, twoside, dvips,

              paperwidth=8.5in, paperheight=11in,

              left=1in, right=1in, top=1.25in, bottom=.75in,

           ]{geometry}

% Make sure hyperref is last in the package list.  Order matters here, See:

%   http://tex.stackexchange.com/questions/77886/fncychap-and-hyperref-messes-up-page-references

\usepackage{hyperref}

\newcommand{\tutorialpartsplit}[2]{#2}

%\input{no-numbers-on-table-of-contents}

\providecommand{\hrefnofollow}[2]{\href{#1}{#2}}

\hypersetup{pdfinfo={Title={Copyleft and the GNU General Public License: A Comprehensive Tutorial and Guide}}}

    \begin{document}

\pagestyle{plain}

\pagenumbering{roman}

\frontmatter

\begin{titlepage}

\begin{center}

{\Huge

{\sc Copyleft and the  \\

GNU General Public License:

\vspace{.25in}

A Comprehensive Tutorial \\

\vspace{.1in}

and Guide

}}

\vfill

{\parindent 0in

\begin{tabbing}

Copyright \> \copyright{} 2014--2015 \>  Anthony K. Sebro, Jr. \\

Copyright \= \copyright{} 2014 \> Denver Gingerich. \\

Copyright \= \copyright{} 2003--2007, 2014 \>  Free Software Foundation, Inc. \\

Copyright \> \copyright{} 2008, 2014 \>  Software Freedom Law Center. \\

\end{tabbing}

\vspace{.3in}

The copyright holders grant the freedom to copy, modify, convey,

adapt, and/or redistribute this work (except

Appendices~\ref{GPLv2-full-text}--\ref{AGPLv3-full-text}) under the terms of the Creative Commons

Attribution Share Alike 4.0 International License.  A copy of that license is

available at \url{https://creativecommons.org/licenses/by-sa/4.0/legalcode}.

Appendices~\ref{GPLv2-full-text}--\ref{AGPLv3-full-text} include copies of the texts of various licenses published

by the FSF, and they are all licensed under the license, ``Everyone is permitted

to copy and distribute verbatim copies of this license document, but changing

it is not allowed.''.  However, those who seek to make modified versions of

those licenses should note the

\href{https://www.gnu.org/licenses/gpl-faq.html#ModifyGPL}{explanation given in the GPL FAQ}.

\vfill

As a public, collaborative project, this Guide is primarily composed of the

many contributions received via its

\href{https://k.copyleft.org/guide/files/master/CONTRIBUTING.md}{public

  contribution process}.  Please

\href{https://k.copyleft.org/guide/changelog/master/}{review its

  Git logs} for full documentation of all contributions, and

Appendix~\ref{third-party-citation-list}

  contains a list of third-party works from which some material herein was

adapted.

The most recent version is

available online at \url{https://copyleft.org/guide/}.  Patches

are indeed welcome to this material.  Sources can be found in the Git

repository at \url{https://k.copyleft.org/guide/}.

}

\end{center}

\end{titlepage}

\tableofcontents

\chapter{Preface}

This tutorial is the culmination of nearly a decade of studying and writing

about software freedom licensing and the GPL\@.  Each part of this tutorial

is a course unto itself, educating the reader on a myriad of topics from the

deep details of the GPLv2 and GPLv3, common business models in the copyleft

licensing area (both the friendly and unfriendly kind), best practices for

compliance with the GPL, for engineers, managers, and lawyers, as well as

real-world case studies of GPL enforcement matters.

It is unlikely that all the information herein is necessary to learn all at

once, and therefore this tutorial likely serves best as a reference book.

The material herein has been used as the basis for numerous live tutorials

and discussion groups since 2002, and the materials have been periodically

updated.   They likely stand on their own as excellent reference material.

However, if you are reading these course materials without attending a live

tutorial session, please note that this material is merely a summary of the

highlights of the various CLE and other tutorial courses based on this

material.  Please be aware that during the actual courses, class discussion

and presentation supplements this printed curriculum.  Simply reading this

material is \textbf{not equivalent} to attending a course.

\mainmatter

% FIXME: We need an Introduction.  I think ideally it goes here, before Part

%  I.  The introduction should cover initially:

%

%

%     * Why we cover the topics in the order that we do, in particular, why

%       we discuss all GPLv2 before mentioning  GPLv3 (i.e., explain why we

%       take a diachronic approach to study of GPL).

%

%     * It should briefly discuss Free Culture / Software Freedom stuff.

%       Maybe some early material currently living in gpl-lgpl.tex should move

%       to the introduction, maybe not.  The goal is to prepare for the

%       moment when we can merge in material about CC-BY-SA.

\input{gpl-lgpl}

\input{compliance-guide}

\input{enforcement-case-studies}

\appendix

\part{Appendices}

\input{third-party-citations}

\input{license-texts}

limited to the patent claims covered by the code as licensed by the patentee.

In contrast, a GPLv2 licensee, under the doctrine of implied patent license, 

is free to practice any patent claims held by the licensor that cover 

``reasonably contemplated uses'' of the GPL'd code, which may very well 

include creation and distribution of modified works since the GPL's terms, 

under which the patented code is distributed, expressly permits such activity.

Further supporting this result is the Federal Circuit's pronouncement that

the recipient of a patented article has, not only an implied license to

make, use, and sell the article, but also an implied patent license to

repair the article to enable it to function properly, Bottom Line Mgmt.,

Inc. v. Pan Man, Inc., 228 F.3d 1352 (Fed. Cir. 2000). Additionally, the

Federal Circuit extended that rule to include any future recipients of the

patented article, not just the direct recipient from the distributor.

This theory comports well with the idea of Free Software, whereby software

is distributed among many entities within the community for the purpose

of constant evolution and improvement. In this way, the law of implied

patent license used by the GPLv2 ensures that the community mutually

benefits from the licensing of patents to any single community member.

Note that simply because GPLv2'd software has an implied patent license does

not mean that any patents held by a distributor of GPLv2'd code become

worthless. To the contrary, the patents are still valid and enforceable

against either:

\begin{enumerate}

 \renewcommand{\theenumi}{\alph{enumi}}

 \renewcommand{\labelenumi}{\textup{(\theenumi)}}

\item any software other than that licensed under the GPLv2 by the patent

  holder, and

\item any party that does not comply with the GPLv2

with respect to the licensed software.

\end{enumerate}

\newcommand{\compB}{$\mathcal{B}$}

\newcommand{\compA}{$\mathcal{A}$}

For example, if Company \compA{} has a patent on advanced Web browsing, but

also licenses a Web browsing program under the GPLv2, then it

cannot assert the patent against any party based on that party's use of 

Company \compA{}'s GPL'd Web browsing software program, or on that party's

creation and use of modified versions of that GPL'd program.  However, if a

party uses that program without

complying with the GPLv2, then Company \compA{} can assert both copyright

infringement claims against the non-GPLv2-compliant party and

infringement of the patent, because the implied patent license only

extends to use of the software in accordance with the GPLv2. Further, if

Company \compB{} distributes a competitive advanced Web browsing program 

that is not a modified version of Company \compA{}'s GPL'd Web browsing software

program, Company \compA{} is free to assert its patent against any user or

distributor of that product. It is irrelevant whether Company \compB's

program is also distributed under the GPLv2, as Company \compB{} can not grant

implied licenses to Company \compA's patent.

This result also reassures companies that they need not fear losing their

proprietary value in patents to competitors through the GPLv2 implied patent

license, as only those competitors who adopt and comply with the GPLv2's

terms can benefit from the implied patent license. To continue the

example above, Company \compB{} does not receive a free ride on Company

\compA's patent, as Company \compB{} has not licensed-in and then

redistributed Company A's advanced Web browser under the GPLv2. If Company

\compB{} does do that, however, Company \compA{} still has not lost

competitive advantage against Company \compB{}, as Company \compB{} must then,

when it re-distributes Company \compA's program, grant an implied license

to any of its patents that cover the program. Further, if Company \compB{}

relicenses an improved version of Company A's program, it must do so under

the GPLv2, meaning that any patents it holds that cover the improved version

are impliedly licensed to any licensee. As such, the only way Company

\compB{} can benefit from Company \compA's implied patent license, is if it,

itself, distributes Company \compA's software program and grants an

implied patent license to any of its patents that cover that program.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\chapter{Defending Freedom on Many Fronts}

Chapters~\ref{run-and-verbatim} and~\ref{source-and-binary} presented the

core freedom-defending provisions of GPLv2\@, which are in GPLv2~\S\S0--3.

GPLv2\S\S~4--7 of the GPLv2 are designed to ensure that GPLv2~\S\S0--3 are

not infringed, are enforceable, are kept to the confines of copyright law but

also not trumped by other copyright agreements or components of other

entirely separate legal systems.  In short, while GPLv2~\S\S0--3 are the parts

of the license that defend the freedoms of users and programmers,

GPLv2~\S\S4--7 are the parts of the license that keep the playing field clear

so that \S\S~0--3 can do their jobs.

\section{GPLv2~\S4: Termination on Violation}

\label{GPLv2s4}

GPLv2~\S4 is GPLv2's termination clause.  Upon first examination, it seems

strange that a license with the goal of defending users' and programmers'

freedoms for perpetuity in an irrevocable way would have such a clause.

However, upon further examination, the difference between irrevocability

The GPL is irrevocable in the sense that once a copyright holder grants

rights for someone to copy, modify and redistribute the software under terms

of the GPL, they cannot later revoke that grant.  Since the GPL has no

provision allowing the copyright holder to take such a prerogative, the

license is granted as long as the copyright remains in effect.\footnote{In

  the USA, due to unfortunate legislation, the length of copyright is nearly

  perpetual, even though the Constitution forbids perpetual copyright.} The

copyright holders have the right to relicense the same work under different

licenses (see Section~\ref{Proprietary Relicensing} of this tutorial), or to

stop distributing the GPLv2'd version (assuming GPLv2~\S3(b) was never used),

but they may not revoke the rights under GPLv2 already granted.

In fact, when an entity loses their right to copy, modify and distribute

GPL'd software, it is because of their \emph{own actions}, not that of the

copyright holder.  The copyright holder does not decide when GPLv2~\S4

termination occurs (if ever); rather, the actions of the licensee determine

that.

Under copyright law, the GPL has granted various rights and freedoms to

the licensee to perform specific types of copying, modification, and

redistribution.  By default, all other types of copying, modification, and

redistribution are prohibited.  GPLv2~\S4 says that if you undertake any of

those other types (e.g., redistributing binary-only in violation of GPLv2~\S3),

then all rights under the license --- even those otherwise permitted for

those who have not violated --- terminate automatically.

GPLv2~\S4 makes GPLv2 enforceable.  If licensees fail to adhere to the

license, then they are stuck without any permission under to engage in

activities covered by copyright law.  They must completely cease and desist

from all copying, modification and distribution of the GPL'd software.

At that point, violating licensees must gain the forgiveness of the copyright

holders to have their rights restored.  Alternatively, the violators could

negotiate another agreement, separate from GPL, with the copyright

holder.  Both are common practice, although

\tutorialpartsplit{as discussed in \textit{A Practical Guide to GPL

    Compliance}, there are }{Chapter~\ref{compliance-understanding-whos-enforcing}

  explains further} key differences between these two very different uses of GPL.

\section{GPLv2~\S5: Acceptance, Copyright Style}

\label{GPLv2s5}

GPLv2~\S5 brings us to perhaps the most fundamental misconception and common

confusion about GPLv2\@. Because of the prevalence of proprietary software,

most users, programmers, and lawyers alike tend to be more familiar with

EULAs. EULAs are believed by their authors to be contracts, requiring

formal agreement between the licensee and the software distributor to be

valid. This has led to mechanisms like ``shrink-wrap'' and ``click-wrap''

as mechanisms to perform acceptance ceremonies with EULAs.

The GPL does not need contract law to ``transfer rights.''  Usually, no rights

are transferred between parties.  By contrast, the GPL is primarily a permission

slip to undertake activities that would otherwise have been prohibited

by copyright law.  As such, GPL needs no acceptance ceremony; the

licensee is not even required to accept the license.

However, without the GPL, the activities of copying, modifying and

distributing the software would have otherwise been prohibited.  So, the

GPL says that you only accepted the license by undertaking activities that

you would have otherwise been prohibited without your license under GPL\@.

This is a certainly subtle point, and requires a mindset quite different

from the contractual approach taken by EULA authors.

An interesting side benefit to GPLv2~\S5 is that the bulk of users of Free

Software are not required to accept the license.  Undertaking fair and

unregulated use of the work, for example, does not bind you to the GPL,

since you are not engaging in activity that is otherwise controlled by

copyright law.  Only when you engage in those activities that might have an

impact on the freedom of others does license acceptance occur, and the

terms begin to bind you to fair and equitable sharing of the software.  In

other words, the GPL only kicks in when it needs to for the sake of

freedom.

While GPL is by default a copyright license, it is certainly still possible

to consider GPL as a contract as well.  For example, some distributors chose

to ``wrap'' their software in an acceptance ceremony to the GPL, and nothing in

the GPL prohibits that use.  Furthermore, the ruling in \textit{Jacobsen

  v. Katzer, 535 F.3d 1373, 1380 (Fed.Cir.2008)} indicates that \textbf{both}

copyright and contractual remedies may be sought by a copyright holder

seeking to enforce a license designed to uphold software freedom.

% FIXME-LATER: Write this

%\section{Using GPL Both as a Contract and Copyright License}

\section{GPLv2~\S6: GPL, My One and Only}

\label{GPLv2s6}

A point that was glossed over in Section~\ref{GPLv2s4}'s discussion of GPLv2~\S4

was the irrevocable nature of the GPL\@. The GPLv2 is indeed irrevocable,

and it is made so formally by GPLv2~\S6.

The first sentence in GPLv2~\S6 ensures that as software propagates down the

distribution chain, that each licensor can pass along the license to each

new licensee.  Under GPLv2~\S6, the act of distributing automatically grants a

license from the original licensor to the next recipient.  This creates a

chain of grants that ensure that everyone in the distribution has rights

under the GPLv2\@.  In a mathematical sense, this bounds the bottom ---

making sure that future licensees get no fewer rights than the licensee before.

The second sentence of GPLv2~\S6 does the opposite; it bounds from the top.  It

prohibits any licensor along the distribution chain from placing

additional restrictions on the user.  In other words, no additional

requirements may trump the rights and freedoms given by GPLv2\@.

The final sentence of GPLv2~\S6 makes it abundantly clear that no individual

entity in the distribution chain is responsible for the compliance of any

other.  This is particularly important for noncommercial users who have

passed along a source offer under GPLv2~\S3(c), as they cannot be assured that

the issuer of the offer will honor their GPLv2~\S3 obligations.

In short, GPLv2~\S6 says that your license for the software is your one and

only copyright license allowing you to copy, modify and distribute the

software.

GPLv2~\S6 is GPLv2's ``automatic downstream licensing''

provision\footnote{This section was substantially expanded for clarity and

  detail in \hyperref[GPLv3s10]{GPLv3~\S10}.}.  Each time you

redistribute a GPL'd program, the recipient automatically receives a license

from each original licensor to copy, distribute or modify the program subject

to the conditions of the license.  The redistributor need not take any

to ensure the downstream recipient's acceptance of the license terms.

This places every copyright holder in the chain of descent of the code

in legal privity, or direct relationship, with every downstream

redistributor.  Two legal effects follow.  First, downstream parties

who remain in compliance have valid permissions for all actions

(including modification and redistribution) even if their immediate upstream

supplier of the software has been terminated for license

violation\footnote{\label{German-reinstatement-footnote} While this is legally true, as a practical matter, a

  failure of ``complete, corresponding source'' (CCS) provisioning by an

  upstream could make it effectively impossible for a downstream party to

  engage in a commercial redistribution pursuant to

  \hyperref[GPLv2s3]{GPLv2~\S3(a--b)}.  (\S~\ref{upstream} in the Compliance

  Guide portion of this tutorial discussed related details.)}.

Downstream's

licensed rights are not dependent on compliance of their upstream, because

their licenses issue directly from the copyright holder.  Second, automatic

termination cannot be cured by obtaining additional copies from an alternate

supplier: the license permissions emanate only from the original licensors,

and if they have automatically terminated permission, no act by any

intermediate license holder can restore those terminated

rights\footnote{While nearly all attorneys and copyleft theorists are in

  agreement on this point, German copyleft legal expert

  \href{http://www.jbb.de/en/attorneys/till-jaeger/}{Till Jaeger}

  vehemently disagrees.  Jaeger's position is as follows: under German

  copyright law, a new copy of GPL'd software is a ``fresh'' license under

  GPL, and if compliance continues from that point further, the violator's

  permissions under copyright law are automatically restored, notwithstanding

  the strict termination provision in \hyperref[GPLv2s4]{GPLv2~\S4}.

  However, in

  practice, this issue is only salient with regard to \hyperref[Proprietary

    Relicensing]{proprietary relicensing} business models, since other copyright

  holders typically formally restore distributions rights once the only

  remaining compliance issue is ``you lost copyright permission due to

  GPLv2~\S4''.  Therefore, the heated debates, which have raged between

  Jaeger and almost everyone else in the copyleft community for nearly a

  decade, regard an almost moot and wholly esoteric legal detail.}.

\section{GPLv2~\S7: ``Give Software Liberty or Give It Death!''}

\label{GPLv2s7}

In essence, GPLv2~\S7 is a verbosely worded way of saying for non-copyright

systems what GPLv2~\S6 says for copyright.  If there exists any reason that a

distributor knows of that would prohibit later licensees from exercising

their full rights under GPL, then distribution is prohibited.

Originally, this was designed as the title of this section suggests --- as

a last ditch effort to make sure that freedom was upheld.  However, in

modern times, it has come to give much more.  Now that the body of GPL'd

software is so large, patent holders who would want to be distributors of

GPL'd software have a tough choice.  They must choose between avoiding

distribution of GPL'd software that exercises the teachings of their

patents, or grant a royalty-free, irrevocable, non-exclusive license to

those patents.  Many companies have chosen the latter.

Thus, GPLv2~\S7 rarely gives software death by stopping its distribution.

Instead, it is inspiring patent holders to share their patents in the same

freedom-defending way that they share their copyrighted works.

\section{GPLv2~\S8: Excluding Problematic Jurisdictions}

\label{GPLv2s8}

GPLv2~\S8 is rarely used by copyright holders.  Its intention is that if a

particular country, say Unfreedonia, grants particular patents or allows

copyrighted interfaces (no country to our knowledge even permits those

yet), that the GPLv2'd software can continue in free and unabated

distribution in the countries where such controls do not exist.

As far as is currently known, GPLv2~\S8 has very rarely been formally used by

copyright holders.  Admittedly, some have used GPLv2~\S8 to explain various

odd special topics of distribution (usually related in some way to

GPLv2~\S7).  However, generally speaking, this section is not proven

particularly useful in the more than two decades of GPLv2 history.

Meanwhile, despite many calls by the FSF (and others) for those licensors who

explicitly use this section to come forward and explain their reasoning, no

one ever did.  Furthermore, research conducted during the GPLv3 drafting

process found exactly one licensor who had invoked this section to add an

explicit geographical distribution limitation, and the reasoning for that one

invocation was not fitting with FSF's intended spirit of GPLv2~\S8.  As such,

GPLv2~\S8 was not included at all in GPLv3.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\chapter{Odds, Ends, and Absolutely No Warranty}

GPLv2~\S\S0--7 constitute the freedom-defending terms of the GPLv2.  The remainder

of the GPLv2 handles administrivia and issues concerning warranties and

liability.

\section{GPLv2~\S9: FSF as Stewards of GPL}

\label{GPLv2s9}

FSF reserves the exclusive right to publish future versions of the GPL\@;

GPLv2~\S9 expresses this.  While the stewardship of the copyrights on the body

of GPL'd software around the world is shared among thousands of

individuals and organizations, the license itself needs a single steward.

Forking of the code is often regrettable but basically innocuous.  Forking

of licensing is disastrous.

(Chapter~\ref{tale-of-two-copylefts} discusses more about the various

versions of GPL.)

\section{GPLv2~\S10: Relicensing Permitted}

\label{GPLv2s10}

GPLv2~\S10 reminds the licensee of what is already implied by the nature of

copyright law.  Namely, the copyright holder of a particular software

program has the prerogative to grant alternative agreements under separate

copyright licenses.

\section{GPLv2~\S11: No Warranty}

\label{GPLv2s11}

Most warranty disclaimer language shouts at you.  The

\href{http://www.law.cornell.edu/ucc/2/2-316}{Uniform Commercial

  Code~\S2-316}, which most of the USA's states and commonwealths have adopted as their local

law, allows disclaimers of warranty, provided that the disclaimer is ``conspicuous''.

There is apparently general acceptance that \textsc{all caps} is the

preferred way to make something conspicuous, and that has over decades worked

its way into the voodoo tradition of warranty disclaimer writing.

That said, there is admittedly some authority under USA law suggesting that

conspicuousness can be established by

capitalization and is absent when a disclaimer has the same typeface as the

terms surrounding it (see \textit{Stevenson v.~TRW, Inc.}, 987 F.2d 288, 296

(5th Cir.~1993)).  While GPLv3's drafters doubted that such authority would

apply to copyright licenses like the GPL, the FSF has nevertheless left

warranty and related disclaimers in \textsc{all caps} throughout all versions

of GPL\@.\footnote{One of the authors of this tutorial, Bradley M.~Kuhn, has

  often suggested the aesthetically preferable compromise of a

  \textsc{specifically designed ``small caps'' font, such as this one, as an

    alternative to} WRITING IN ALL CAPS IN THE DEFAULT FONT (LIKE THIS),

  since the latter adds more ugliness than conspicuousness.  Kuhn once

  engaged in reversion war with a lawyer who disagreed, but that lawyer never

not excepted by the additional permission granted in LGPLv3.

If the distributor of the combined work intends not to distribute or offer

the source code of the LGPL'd components, the LGPL'd work must be separately

distributed (subject to source code delivery requirements as part of that

separate distribution) and packaged in a ``shared library'' mechanism, which

means that it:

\begin{quote}

\begin{enumerate}[label=4(d)(\arabic*):,ref=LGPLv3s4d\arabic*]

  \item uses at run time a copy of the library already present on

    the user's computer system, rather than copying library functions into

    the executable, and

  \item will operate properly with a modified version of

    the library, if the user installs one, as long as the modified version is

    interface-compatible with the version that the work was made with.

\end{enumerate}

\end{quote}

Taken all together, LGPLv3~\S4's primary implications for redistributors are

two-fold, as follows:

\begin{itemize}

\item  If you create a program that links through a shared library mechanism to

    a work that is separately distributed under LGPLv3, then you can

    distribute the resultant program under a license of your choice and you

    need not convey the LGPLv3'd work's source code. If you distribute the

    library along with your program, or are the separate distributor of the

    work in another context or as another product, you must distribute its

    corresponding source under the terms of LGPLv3 or GPLv3-or-later.

\item If you choose to statically link or otherwise combine your program with

    an LGPLv3'd work via mechanisms other than a shared library, you may choose your own license for the work provided the

    license terms limitations for user modification, reverse engineering and

    debugging are met, and given that the LGPL'd components are still

    governed by LGPL's terms. You must offer or provide CCS for the LGPL'd components. The source code

    material provided must be sufficient to regenerate the combined work with

    a user-modified version of the LGPL'd components.

\end{itemize}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% FIXME-LATER: There should be a chapter on GPL Exceptions generally.

% Here is some CC-By-SA text from another source that would make an

% acceptable introduction to a section on the GCC RTL Exception if such a

% chapter is written:

% This GCC Runtime Library Exception (``Exception'') is an additional

% permission as provided by Section 7 of GPLv3. The purpose of this Exception

% is to allow compilation of non-GPL (including proprietary) programs making

% use of the header files and runtime libraries covered by this Exception and

% containing code from the copyleft toolchain embedded by the compiler in the

% object code of the program as part of the compilation process. The GCC

% Runtime Library Exception covers any file that has a notice in its license

% headers stating that the exception applies.

% FIXME-LATER: end

\chapter{Integrating the GPL into Business Practices}

Since GPL'd software is now extremely prevalent through the industry, it

is useful to have some basic knowledge about using GPL'd software in

business and how to build business models around GPL'd software.

\section{Using GPL'd Software In-House}

As discussed in Sections~\ref{GPLv2s0} and~\ref{GPLv2s5} of this tutorial,

the GPL only governs the activities of copying, modifying and

distributing software programs that are not governed by the license.

Thus, in FSF's view, simply installing the software on a machine and

using it is not controlled or limited in any way by the GPL\@. Using Free

Software in general requires substantially fewer agreements and less

license compliance activity than any known proprietary software.

Even if a company engages heavily in copying the software throughout the

enterprise, such copying is not only permitted by GPLv2~\S\S1 and 3, but it is

encouraged!  If the company simply deploys unmodified (or even modified)

Free Software throughout the organization for its employees to use, the

obligations under the license are very minimal. Using Free Software has a

substantially lower cost of ownership --- both in licensing fees and in

licensing checking and handling -- than the proprietary software

equivalents.

\section{Business Models}

\label{Business Models}

Using Free Software in house is certainly helpful, but a thriving

market for Free Software-oriented business models also exists. There is the

traditional model of selling copies of Free Software distributions.

Many companies make substantial revenue

from this model. Some choose this model because they have

found that for higher-end hardware, the profit made from proprietary

software licensing fees is negligible. The real profit is in the hardware,

but it is essential that software be stable, reliable and dependable, and

the users be allowed to have unfettered access to it. Free Software, and

assured that proprietary versions of the their software will not exist to

compete on their hardware.

For example, charging a ``convenience fee'' for Free Software,

when set at a reasonable price (around \$60 or so), can produce some

profit. Even though Red Hat's system is fully downloadable on their

Web site, people still go to local computer stores and buy copies of their

box set, which is simply a printed version of the manual (available under

a Free license as well) and the Free Software system it documents.

\medskip

Custom support, service, and software improvement contracts

are the most widely used models for GPL'd software. The GPL is

central to their success, because it ensures that the code base

remains common, and that large and small companies are on equal

footing for access to the technology. Consider, for example, the GNU

Compiler Collection (GCC). Cygnus Solutions, a company started in the

early 1990s, was able to grow steadily simply by providing services

for GCC --- mostly consisting of new ports of GCC to different or new,

embedded targets. Eventually, Cygnus was so successful that

it was purchased by Red Hat where it remains a profitable division.

However, there are very small companies that compete in

this space. Modern industry demands the trust created by GPL protected

code-bases. Companies can cooperate on the software and

improve it for everyone. Meanwhile, companies who rely on GCC for their

work are happy to pay for improvements, and for ports to new target

platforms. Nearly all the changes fold back into the standard

versions, and those forks that exist remain freely available.

\medskip

\label{Proprietary Relicensing}

A final common business model that is perhaps the most controversial is

proprietary relicensing of a GPL'd code base. This is only an option for

software in which a particular entity holds exclusive rights to

relicense.\footnote{Entities typically hold exclusive relicensing rights

  either by writing all the software under their own copyrights, collecting

  copyright assignments from all contributors, or by otherwise demanding

  unconditional relicensing permissions from all contributors via some legal

  agreement} As discussed earlier in this tutorial, a copyright holder is

permitted under copyright law to license a software system under her

copyright as many different ways as she likes to as many different parties as

she wishes.

Some companies use this to their

financial advantage with regard to a GPL'd code base. The standard

version is available from the company under the terms of the GPL\@.

However, parties can purchase separate proprietary software licensing for

a fee.

This business model is at best problematic and at worst predatory because it means that the GPL'd code

base must be developed in a somewhat monolithic way, because volunteer

Free Software developers may be reluctant to assign their copyrights to

the company because it will not promise to always and forever license the

software as Free Software. Indeed, the company will surely use such code

contributions in proprietary versions licensed for fees.

\section{Ongoing Compliance}

GPL compliance is in fact a very simple matter --- much simpler than

typical proprietary software agreements and EULAs. Usually, the most

difficult hurdle is changing from a proprietary software mindset to one

that seeks to foster a community of sharing and mutual support. Certainly

complying with the GPL from a users' perspective gives substantially fewer

headaches than proprietary license compliance.

For those who go into the business of distributing {\em modified}

versions of GPL'd software, the burden is a bit higher, but not by

much. The glib answer is that by releasing the whole product as Free

Software, it is always easy to comply with the GPL. However,

admittedly to the dismay of FSF, many modern and complex software

systems are built using both proprietary and GPL'd components that are

clearly and legally separate and independent works, merely aggregated

together on the same device.

However, it sometimes is easier, quicker, and cheaper to simply

improve an existing GPL'd application than to start from scratch.  In

exchange for this amazing benefit, the license requires that the modifier gives

back to the commons that made the work easier in the first place. It is a

reasonable trade-off and a way to help build a better world while also

making a profit.

Note that FSF does provide services to assist companies who need

assistance in complying with the GPL. You can contact FSF's GPL

Compliance Labs at $<$licensing@fsf.org$>$.

%FIXME-LATER: should have \tutorialpart

If you are particularly interested in matters of GPL compliance, we

recommend the next two parts, which include both recommendations on good

compliance and compliance case studies.