Generally speaking, copyright law operates similarly enough in countries that

have signed the Berne Convention on Copyright, and software freedom licenses

have generally taken advantage of this international standardization of

copyright law.  However, copyright law does differ from country to country,

and commonly, software freedom licenses like GPL must be considered under the

copyright law in the jurisdiction where any licensing dispute occurs.

Those who are most familiar with the USA's system of copyright often are

surprised to learn that there are certain copyright controls that cannot be

waived nor disclaimed.  Specifically, many copyright regimes outside the USA

recognize a concept of moral rights of authors.  Typically, moral rights are

fully compatible with respecting software freedom, as they are usually

centered around controls that software freedom licenses generally respect,

such as the right of an authors to require proper attribution for their work.

\section{A Community of Equality}

The previous section described the principles of software freedom, a brief

introduction to mechanisms that typically block these freedoms, and the

simplest ways that copyright holders might grant those freedoms to their

users for their copyrighted works of software.  The previous section also

introduced the idea of \textit{copyleft}: a licensing mechanism to use

copyright to not only grant software freedom to users, but also to uphold

those rights against those who might seek to curtail them.

Copyleft, as defined in \S~\ref{copyleft-definition}, is a general term this

mechanism.  The remainder of this text will discuss details of various

real-world implementations of copyleft -- most notably, the GPL\@.

This discussion begins first with some general explanation of what the GPL is

able to do in software development communities.  After that brief discussion

in this section, deeper discussion of how GPL accomplishes this in practice

follows in the next chapter.

Simply put, though, the GPL ultimately creates an community of equality for

both business and noncommercial users.

\subsection{The Noncommercial Community}

A GPL'd code base becomes a center of a vibrant development and user

community.  Traditionally, volunteers, operating noncommercially out of

keen interest or ``scratch an itch'' motivations, produce initial versions

of a GPL'd system.  Because of the efficient distribution channels of the

Internet, any useful GPL'd system is adopted quickly by noncommercial

users.

Fundamentally, the early release and quick distribution of the software

gives birth to a thriving noncommercial community.  Users and developers

begin sharing bug reports and bug fixes across a shared intellectual

commons.  Users can trust the developers, because they know that if the

developers fail to address their needs or abandon the project, the GPL

ensures that someone else has the right to pick up development.

Developers know that the users cannot redistribute their software without

passing along the rights granted by GPL, so they are assured that every

one of their users is treated equally.

Because of the symmetry and fairness inherent in GPL'd distribution,

nearly every GPL'd package in existence has a vibrant noncommercial user

and developer base.

\subsection{The Commercial Community}

By the same token, nearly all established GPL'd software systems have a

vibrant commercial community.  Nearly every GPL'd system that has gained

wide adoption from noncommercial users and developers eventually begins

to fuel a commercial system around that software.

For example, consider the Samba file server system that allows Unix-like

systems (including GNU/Linux) to serve files to Microsoft Windows systems.

Two graduate students originally developed Samba in their spare time and

it was deployed noncommercially in academic environments\footnote{See

  \href{http://turtle.ee.ncku.edu.tw/docs/samba/history}{Andrew Tridgell's

    ``A bit of history and a bit of fun''}}.  However, very

soon for-profit companies discovered that the software could work for them

as well, and their system administrators began to use it in place of

Microsoft Windows NT file-servers.  This served to lower the cost of

running such servers by orders of magnitude. There was suddenly room in

Windows file-server budgets to hire contractors to improve Samba.  Some of

the first people hired to do such work were those same two graduate

students who originally developed the software.

The noncommercial users, however, were not concerned when these two

fellows began collecting paychecks off of their GPL'd work.  They knew

that because of the nature of the GPL that improvements that were

distributed in the commercial environment could easily be folded back into

the standard version.  Companies are not permitted to proprietarize

Samba, so the noncommercial users, and even other commercial users are

safe in the knowledge that the software freedom ensured by GPL will remain

protected.

Commercial developers also work in concert with noncommercial

developers.  Those two now-long-since graduated students continue to

contribute to Samba altruistically, but also get paid work doing it.

Priorities change when a client is in the mix, but all the code is

contributed back to the standard version.  Meanwhile, many other

individuals have gotten involved noncommercially as developers,

because they want to ``cut their teeth on Free Software,'' or because

the problems interest them.  When they get good at it, perhaps they

will move on to another project, or perhaps they will become

commercial developers of the software themselves.

No party is a threat to another in the GPL software scenario because

everyone is on equal ground.  The GPL protects rights of the commercial

and noncommercial contributors and users equally. The GPL creates trust,

because it is a level playing field for all.

\subsection{Law Analogy}

In his introduction to Stallman's \emph{Free Software, Free Society},

Lawrence Lessig draws an interesting analogy between the law and Free

Software. He argues that the laws of a free society must be protected

much like the GPL protects software.  So that I might do true justice to

Lessig's argument, I quote it verbatim:

\begin{quotation}

A ``free society'' is regulated by law. But there are limits that any free

society places on this regulation through law: No society that kept its

laws secret could ever be called free.  No government that hid its

regulations from the regulated could ever stand in our tradition. Law

controls.  But it does so justly only when visibly.  And law is visible

only when its terms are knowable and controllable by those it regulates,

or by the agents of those it regulates (lawyers, legislatures).

This condition on law extends beyond the work of a legislature.  Think

about the practice of law in American courts.  Lawyers are hired by their

clients to advance their clients' interests.  Sometimes that interest is

advanced through litigation. In the course of this litigation, lawyers

write briefs. These briefs in turn affect opinions written by judges.

These opinions decide who wins a particular case, or whether a certain law

can stand consistently with a constitution.

All the material in this process is free in the sense that Stallman means.

Legal briefs are open and free for others to use.  The arguments are

transparent (which is different from saying they are good), and the

reasoning can be taken without the permission of the original lawyers.

The opinions they produce can be quoted in later briefs.  They can be

copied and integrated into another brief or opinion.  The ``source code''

for American law is by design, and by principle, open and free for anyone

to take. And take lawyers do---for it is a measure of a great brief that

it achieves its creativity through the reuse of what happened before.  The

source is free; creativity and an economy is built upon it.

This economy of free code (and here I mean free legal code) doesn't starve

lawyers.  Law firms have enough incentive to produce great briefs even

though the stuff they build can be taken and copied by anyone else.  The

lawyer is a craftsman; his or her product is public.  Yet the crafting is

not charity. Lawyers get paid; the public doesn't demand such work

without price.  Instead this economy flourishes, with later work added to

the earlier.

We could imagine a legal practice that was different --- briefs and

arguments that were kept secret; rulings that announced a result but not

the reasoning. Laws that were kept by the police but published to no one

else. Regulation that operated without explaining its rule.

We could imagine this society, but we could not imagine calling it

``free.''  Whether or not the incentives in such a society would be better

or more efficiently allocated, such a society could not be known as free.

The ideals of freedom, of life within a free society, demand more than

efficient application.  Instead, openness and transparency are the

constraints within which a legal system gets built, not options to be

added if convenient to the leaders.  Life governed by software code should

be no less.

Code writing is not litigation.  It is better, richer, more

productive.  But the law is an obvious instance of how creativity and

incentives do not depend upon perfect control over the products

created.  Like jazz, or novels, or architecture, the law gets built

upon the work that went before. This adding and changing is what

creativity always is.  And a free society is one that assures that its

most important resources remain free in just this sense.\footnote{This

quotation is Copyright \copyright{} 2002, Lawrence Lessig. It is

licensed under the terms of

\href{http://creativecommons.org/licenses/by/1.0/}{the ``Attribution

License'' version 1.0} or any later version as published by Creative

Commons.}

\end{quotation}

In essence, lawyers are paid to service the shared commons of legal

infrastructure.  Few citizens defend themselves in court or write their

own briefs (even though they are legally permitted to do so) because

everyone would prefer to have an expert do that job.

The Free Software economy is a market ripe for experts.  It

functions similarly to other well established professional fields like the

law. The GPL, in turn, serves as the legal scaffolding that permits the

creation of this vibrant commercial and noncommercial Free Software

economy.

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

\chapter{A Tale of Two Copyleft Licenses}

While determining the proper methodology and criteria to yield an accurate

count remains difficult, the GPL is generally considered one of the most

widely used Free Software licenses.  For most of its history --- for 16 years

from June 1991 to June 2007 --- there was really only one version of the GPL,

version 2.

However, the GPL had both earlier versions before version 2, and, more well

known, a revision to version 3. 

\section{Historical Motivations for the General Public License}

The earliest license to grant software freedom was likely the Berkeley

Software Distribution (``BSD'') license.  This license is typical of what are

often called lax, highly permissive licenses.  Not unlike software in the

public domain, these non-copyleft licenses (usually) grant software freedom

to users, but they do not go to any effort to uphold that software freedom

for users.  The so-called ``downstream'' (those who receive the software and

then build new things based on that software) can restrict the software and

distribute further.

The GNU's Not Unix (``GNU'') project, which Richard M.~Stallman (``RMS'')

founded in 1984 to make a complete Unix-compatible operating system

implementation that assured software freedom for all.  However, RMS saw that

using a license that gave but did not assure software freedom would be

counter to the goals of the GNU project.  RMS invented ``copyleft'' as an

answer to that problem, and began using various copyleft licenses for the

early GNU project programs\footnote{RMS writes more fully about this topic in

  his essay entitled simply

  \href{http://www.gnu.org/gnu/thegnuproject.html}{\textit{The GNU Project}}.

    For those who want to hear the story in his own voice,

    \href{http://audio-video.gnu.org/audio/}{speech recordings} of his talk,

    \textit{The Free Software Movement and the GNU/Linux Operating System}

    are also widely available}.

\section{Proto-GPLs And Their Impact}

The earliest copyleft licenses were specific to various GNU programs.  For

example, \href{http://www.free-soft.org/gpl_history/emacs_gpl.html}{The Emacs

  General Public License} was likely the first copyleft license ever

published.  Interesting to note that even this earliest copyleft license

contains a version of the well-known GPL copyleft clause:

\begin{quotation}

You may modify your copy or copies of GNU Emacs \ldots provided that you also

\ldots cause the whole of any work that you distribute or publish, that in

whole or in part contains or is a derivative of GNU Emacs or any part

thereof, to be licensed at no charge to all third parties on terms identical

to those contained in this License Agreement.

\end{quotation}

This simply stated clause is the fundamental innovation of copyleft.

Specifically, copyleft \textit{uses} the copyright holders' controls on

permission to modify the work to add a conditional requirement.  Namely,

downstream users may only have permission to modify  the work if they pass

along the same permissions on the modified version that came originally to

them.

These original program-specific proto-GPLs give an interesting window into

the central ideas and development of copyleft.  In particular, reviewing them

shows how the text of the GPL we know has evolved to address more of the

issues discussed earlier in \S~\ref{software-and-non-copyright}.

\section{The GNU General Public License, Version 1}

\label{GPLv1}

In January 1989, the FSF announced that the GPL had been converted into a

``subroutine'' that could be reused not just for all FSF-copyrighted

programs, but also by anyone else.  As the FSF claimed in its announcement of

the GPLv1\footnote{The announcement of GPLv1 was published in the

  \href{http://www.gnu.org/bulletins/bull6.html\#SEC8}{GNU'S Bulletin, vol 1,

    number 6 dated January 1989}.  (Thanks very much to Andy Tai for his

  \href{http://www.free-soft.org/gpl_history/}{consolidation of research on

    the history of the pre-v1 GPL's}.)}:

\begin{quotation}

To make it easier to copyleft programs, we have been improving on the

legalbol architecture of the General Public License to produce a new version

that serves as a general-purpose subroutine: it can apply to any program

without modification, no matter who is publishing it.

\end{quotation}

This, like many inventive ideas, seems somewhat obvious in retrospect.  But,

the FSF had some bright people and access to good lawyers when it started.

It took almost five years from the first copyleft licenses to get to a

generalized, reusable GPLv1.  In the context and mindset of the 1980s, this

is not surprising.  The idea of reusable licensing infrastructure was not

only uncommon, it was virtually nonexistent!  Even the early BSD licenses

were simply copied and rewritten slightly for each new use\footnote{It

  remains an interesting accident of history that the early BSD problematic

  ``advertising clause'' (discussion of which is somewhat beyond the scope of

  this tutorial) lives on into current day, simply because while the

  University of California at Berkeley gave unilateral permission to remove

  the clause from \textit{its} copyrighted works, others who adapted the BSD

  license with their own names in place of UC-Berkeley's never have.}.  The

GPLv1's innovation of reuable licensing infrastructure, an obvious fact

today, was indeed a novel invention for its day\footnote{We're all just

  grateful that the FSF also opposes business method patents, since the FSF's

  patent on a ``method for reusable licensing infrastructure'' would have

  not expired until 2006!}.

\section{The GNU General Public License, Version 2}

The GPLv2 was released two and a half years after GPLv1, and over the

following sixteen years, it became the standard for copyleft licensing until

the release of GPLv3 in 2007 (discussed in more detail in the next section).

While this tutorial does not discuss the terms of GPLv1 in detail, it is

worth noting below the three key changes that GPLv2 brought:

\begin{itemize}

\item Software patents and their danger are explicitly mentioned, inspiring

  (in part) the addition of GPLv2~\S\S5--7.  (These sections are discussed in

  detail in \S~\ref{GPLv2s5}, \S~\ref{GPLv2s6} and \S~\ref{GPLv2s7} of this

  tutorial.)

\item GPLv2~\S2's copyleft terms are expanded to more explicitly discuss the

  issue of combined works.  (GPLv2~\S2 is discussed in detail in

  \S~\ref{GPLv2s2} in this tutorial).

\item GPLv2~\S3 includes more detailed requirements, including the phrase

 ``the scripts used to control compilation and installation of the

  executable'', which is a central component of current GPLv2 enforcement

  .  (GPLv2~\S3 is discussed in detail in

  \S~\ref{GPLv2s3} in this tutorial).

\end{itemize}

The next chapter discusses GPLv2 in full detail, and readers who wish to dive

into the section-by-section discussion of the GPL should jump ahead now to

that chapter.  However, the most interesting fact to note here is how GPLv2

was published with little fanfare and limited commentary.  This contrasts

greatly with the creation of GPLv3.

\section{The GNU General Public License, Version 3}

RMS began drafting GPLv2.2 in mid-2002, and FSF ran a few discussion groups

during that era about new text of that license.  However, rampant violations

of the GPL required more immediate attention of FSF's licensing staff, and as

such, much of the early 2000's was spent doing GPL enforcement

work\footnote{More on GPL enforcement is discussed in \tutorialpartsplit{a

    companion tutorial, \texit{A Practical Guide to GPL

      Compliance}}{Part~\ref{gpl-compliance-guide} of this tutorial}.}.  In

2006, FSF began in earnest drafting work for GPLv3.

The GPLv3 process began in earnest in January 2006.  It became clear that

many provisions of the GPL could benefit from modification to fit new

circumstances and to reflect what the entire community learned from

experience with version 2.  Given the scale of revision it seems proper to

approach the work through public discussion in a transparent and accessible

manner.

The GPLv3 process continued through June 2007, culminating in publication of

GPLv3 and LGPLv3 on 29 June 2007, AGPLv3 on 19 November 2007, and the GCC

Runtime Library Exception on 27 January 2009.

All told, four discussion drafts of GPLv3, two discussion drafts of LGPLv3

and two discussion drafts of AGPLv3 were published and discussed.

Ultimately, FSF remained the final arbiter and publisher of the licenses, and

RMS himself their primary author, but input was sought from many parties, and

these licenses do admittedly look and read more like legislation as a result.

Nevertheless, all of the ``v3'' group are substantially better and improved

licenses.

GPLv3 and its terms are discussed in detail in Chapter\~ref{GPLv3}.

\section{The Innovation of Optional ``Or Any Later'' Version}

An interesting fact of all GPL licenses is that the are ultimate multiple

choices for use of the license.  The FSF is the primary steward of GPL (as

discussed later in \S~\ref{GPLv2s9} and \S~\ref{GPLv2s14}).  However, those

who wish to license works under GPL are not required to automatically accept

changes made by the FSF for their own copyrighted works.

Each licensor may chose three different methods of licensing, as follows:

\begin{itemize}

\item explicitly name a single version of GPL for their work (usually

  indicated in shorthand by saying the license is ``GPLv$X$-only''), or

\item name no version of the GPL, thus they allow their downstream recipients

  to select any version of the GPL they chose (usually indicated in shorthand

  by saying the license is simply ``GPL''), or

\item name a specific version of GPL and give downstream recipients the

  option to chose that version ``or any later version as published by the

  FSF'' (usually indicated by saying the license is

  ``GPLv$X$-or-later'')\footnote{The shorthand of ``GPL$X+$'' is also popular

    for this situation.  The authors of this tutorial prefer ``-or-later''

    syntax, because it (a) mirrors the words ``or'' and ``later from the

    licensing statement, (b) the $X+$ doesn't make it abundantly clear that

    $X$ is clearly included as a license option and (c) the $+$ symbol has

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

and this termination clause becomes clear.

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 looses 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 decided 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 transfered 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 GPL, and nothing in

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.

\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.

\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 never been formally used by any

copyright holders.  Some have used GPLv2~\S8 to explain various odd special

topics of distribution, but generally speaking, this section is not

particularly useful and was actually removed 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.

\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}

All warranty disclaimer language tends to be shouted in all capital

letters. Apparently, there was once a case where the disclaimer language

of an agreement was negated because it was not ``conspicuous'' to one of

the parties. Therefore, to make such language ``conspicuous,'' people

started placing it in bold or capitalizing the entire text. It now seems

to be voodoo tradition of warranty disclaimer writing.

Some have argued the GPL is unenforceable in some jurisdictions because

its disclaimer of warranties is impermissibly broad. However, GPLv2~\S11

contains a jurisdictional savings provision, which states that it is to be

interpreted only as broadly as allowed by applicable law. Such a

provision ensures that both it, and the entire GPL, is enforceable in any

jurisdiction, regardless of any particular law regarding the

permissibility of certain warranty disclaimers.

Finally, one important point to remember when reading GPLv2~\S11 is that GPLv2~\S1

permits the sale of warranty as an additional service, which GPLv2~\S11 affirms.

\section{GPLv2~\S12: Limitation of Liability}

\label{GPLv2s12}

There are many types of warranties, and in some jurisdictions some of them

cannot be disclaimed. Therefore, usually agreements will have both a

warranty disclaimer and a limitation of liability, as we have in GPLv2~\S12. \S

11 thus gets rid of all implied warranties that can legally be

disavowed. GPLv2~\S12, in turn, limits the liability of the actor for any

warranties that cannot legally be disclaimed in a particular jurisdiction.

Again, some have argued the GPL is unenforceable in some jurisdictions

because its limitation of liability is impermissibly broad. However, \S

12, just like its sister, GPLv2~\S11, contains a jurisdictional savings

provision, which states that it is to be interpreted only as broadly as

allowed by applicable law. As stated above, such a provision ensures that

both GPLv2~\S12, and the entire GPL, is enforceable in any jurisdiction,

regardless of any particular law regarding the permissibility of limiting

liability.

So end the terms and conditions of the GNU General Public License.

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

\chapter{GPLv3}

\label{GPLv3}

\section{Understanding GPLv3 As An Upgraded GPLv2}

\section{GPLv3~\S0: Giving In On ``Defined Terms''}

\section{GPLv3~\S1: Understanding CCS}

\section{GPLv3~\S2: Basic Permissions}

\section{GPLv3~\S3: What Hath DMCA Wrought}

\label{GPLv3s3}

\section{GPLv3~\S4: Verbatim Copying}

\section{GPLv3~\S5: Modified Source}

\section{GPLv3~\S6: Non-Source and Corresponding Source}

\section{Understanding License Compatibility}

\label{license-compatibility}

\section{GPLv3~\S7: Explicit Compatibility}

\section{GPLv3~\S8: A Lighter Termination}

\section{GPLv3~\S9: Acceptance}

\section{GPLv3~\S10: Explicit Downstream License}

\section{GPLv3~\S11: Explicit Patent Licensing}

\label{GPLv3s11}

\section{GPLv3~\S12: Familiar as GPLv2 \S 7}

\section{GPLv3~\S13: The Great Affero Compromise}

\section{GPLv3~\S14: So, When's GPLv4?}

\label{GPlv2s14}

\section{GPLv3~\S15--17: Warranty Disclaimers and Liability Limitation}

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

\chapter{The Lesser GPL}

As we have seen in our consideration of the GPL, its text is specifically

designed to cover all possible derivative works under copyright law. Our

goal in designing GPL was to make sure that any derivative work of GPL'd

software was itself released under GPL when distributed. Reaching as far

as copyright law will allow is the most direct way to reach that goal.

However, while the strategic goal is to bring as much Free Software

into the world as possible, particular tactical considerations

regarding software freedom dictate different means. Extending the

copyleft effect as far as copyright law allows is not always the most

prudent course in reaching the goal. In particular situations, even

those of us with the goal of building a world where all published

software is Free Software realize that full copyleft does not best

serve us. The GNU Lesser General Public License (``GNU LGPL'') was

designed as a solution for such situations.

\section{The First LGPL'd Program}

The first example that FSF encountered where such altered tactics were

needed was when work began on the GNU C Library. The GNU C Library would

become (and today, now is) a drop-in replacement for existing C libraries.

On a Unix-like operating system, C is the lingua franca and the C library

is an essential component for all programs. It is extremely difficult to

construct a program that will run with ease on a Unix-like operating

system without making use of services provided by the C library --- even

if the program is written in a language other than C\@. Effectively, all

user application programs that run on any modern Unix-like system must

make use of the C library.

By the time work began on the GNU implementation of the C libraries, there

were already many C libraries in existence from a variety of vendors.

Every proprietary Unix vendor had one, and many third parties produced

smaller versions for special purpose use. However, our goal was to create

a C library that would provide equivalent functionality to these other C

libraries on a Free Software operating system (which in fact happens today

on modern GNU/Linux systems, which all use the GNU C Library).

Unlike existing GNU application software, however, the licensing

implications of releasing the GNU C Library (``glibc'') under GPL were

somewhat different. Applications released under GPL would never

themselves become part of proprietary software. However, if glibc were

released under GPL, it would require that any application distributed for

the GNU/Linux platform be released under GPL\@.

Since all applications on a Unix-like system depend on the C library, it

means that they must link with that library to function on the system. In

other words, all applications running on a Unix-like system must be

combined with the C library to form a new whole derivative work that is

composed of the original application and the C library. Thus, if glibc

were GPL'd, each and every application distributed for use on GNU/Linux

would also need to be GPL'd, since to even function, such applications

would need to be combined into larger derivative works by linking with

glibc.

At first glance, such an outcome seems like a windfall for Free Software

advocates, since it stops all proprietary software development on

GNU/Linux systems. However, the outcome is a bit more subtle. In a world

where many C libraries already exist, many of which could easily be ported

to GNU/Linux, a GPL'd glibc would be unlikely to succeed. Proprietary

vendors would see the excellent opportunity to license their C libraries

to anyone who wished to write proprietary software for GNU/Linux systems.

The de-facto standard for the C library on GNU/Linux would likely be not

glibc, but the most popular proprietary one.

Meanwhile, the actual goal of releasing glibc under GPL --- to ensure no

proprietary applications on GNU/Linux --- would be unattainable in this

scenario. Furthermore, users of those proprietary applications would also

be users of a proprietary C library, not the Free glibc.

The Lesser GPL was initially conceived to handle this scenario. It was

clear that the existence of proprietary applications for GNU/Linux was

inevitable. Since there were so many C libraries already in existence, a

new one under GPL would not stop that tide. However, if the new C library

were released under a license that permitted proprietary applications

to link with it, but made sure that the library itself remained Free,

an ancillary goal could be met. Users of proprietary applications, while

they would not have the freedom to copy, share, modify and redistribute

the application itself, would have the freedom to do so with respect to

the C library.

There was no way the license of glibc could stop or even slow the creation

of proprietary applications on GNU/Linux. However, loosening the

restrictions on the licensing of glibc ensured that nearly all proprietary

applications at least used a Free C library rather than a proprietary one.

This trade-off is central to the reasoning behind the LGPL\@.

Of course, many people who use the LGPL today are not thinking in these

terms. In fact, they are often choosing the LGPL because they are looking

for a ``compromise'' between the GPL and the X11-style liberal licensing.

However, understanding FSF's reasoning behind the creation of the LGPL is

helpful when studying the license.

\section{What's the Same?}

Much of the text of the LGPL is identical to the GPL\@. As we begin our