work must be GPL and only GPL\@.  In this manner, GPLv2~\S2(b) dovetails nicely

with GPLv2~\S6 (as discussed in Section~\ref{GPLv2s6} of this tutorial).

\medskip

The final paragraph of GPLv2~\S2 is worth special mention.  It is possible and

quite common to aggregate various software programs together on one

distribution medium.  Computer manufacturers do this when they ship a

pre-installed hard drive, and GNU/Linux distribution vendors do this to

give a one-stop CD or URL for a complete operating system with necessary

applications.  The GPL very clearly permits such ``mere aggregation'' with

programs under any license.  Despite what you hear from its critics, the

GPL is nothing like a virus, not only because the GPL is good for you and

a virus is bad for you, but also because simple contact with a GPL'd

code-base does not impact the license of other programs.  A programmer must

expend actual effort  to cause a work to fall under the terms

of the GPL.  Redistributors are always welcome to simply ship GPL'd

software alongside proprietary software or other unrelated Free Software,

as long as the terms of GPL are adhered to for those packages that are

truly GPL'd.

%FIXME: need discussion of GPLv2's system library exception somewhere in here.

\subsection{Right to Private Modification} 

\label{gplv2-private-modification}

The issue of private modifications of GPLv2'd works deserves special

attention.  While these rights are clearly explicit in GPLv3~\S2\P2 (see

\S~\ref{GPLv3S2} of this tutorial for details), the permission to create

private modifications is mostly implicit in GPLv2.  Most notably, the

requirements of GPLv2~\S2 (and GPLv2~\S3, which will be discussed next) are

centered around two different copyright controls: both modification

\emph{and} distribution.  As such, GPLv2~\S2's requirements need only be met

when a modified version is distributed; one need not follow them for modified

versions that are not distributed\footnote{As a matter of best practice, it's

  useful to assume that all software may eventually be distributed later,

  even if there no plans for distribution at this time.  Too often, GPL

  violations occur because of a late distribution decision of software that

  was otherwise never intended for distribution.}.

However, the careful reader of GPLv2 will notice that, unlike GPLv3, no other

clauses of the license actually give explicit permission to make private

modifications.  Since modification of software is a control governed by

copyright, a modifier needs permission from the copyright holder to engage in

that activity.

In practice, however, traditional GPLv2 interpretation has always assumed

that blanket permission to create non-distributed modified versions was

available, and the

\href{http://www.gnu.org/licenses/gpl-faq.html#GPLRequireSourcePostedPublic}{FSF

  has long opined that distribution of modified versions is never mandatory}.

This issue is one of many where GPLv3 clarifies in explicit text the implicit

policy and intent that was solidified via long-standing interpretation of

GPLv2.

\section{GPLv2~\S3: Producing Binaries}

\label{GPLv2s3}

Software is a strange beast when compared to other copyrightable works.

It is currently impossible to make a film or a book that can be truly

obscured.  Ultimately, the full text of a novel, even one written by

William Faulkner, must be presented to the reader as words in some

human-readable language so that they can enjoy the work.  A film, even one

directed by David Lynch, must be perceptible by human eyes and ears to

have any value.

Software is not so.  While the source code --- the human-readable

representation of software --- is of keen interest to programmers, users and

programmers alike cannot make the proper use of software in that

human-readable form.  Binary code --- the ones and zeros that the computer

can understand --- must be predicable and attainable for the software to

be fully useful.  Without the binaries, be they in object or executable

form, the software serves only the didactic purposes of computer science.

Under copyright law, binary representations of the software are simply

modified versions (and/or derivative works) of the source code.  Applying a systematic process (i.e.,

``compilation''\footnote{``Compilation'' in this context refers to the

  automated computing process of converting source code into binaries.  It

  has absolutely nothing to do with the term ``compilation'' in copyright statues.}) to a work of source code yields binary code. The binary

code is now a new work of expression fixed in the tangible medium of

electronic file storage.

Therefore, for GPL'd software to be useful, the GPL, since it governs the

rules for creation of modified works, must grant permission for the

generation of binaries.  Furthermore, notwithstanding the relative

popularity of source-based GNU/Linux distributions like Gentoo, users find

it extremely convenient to receive distribution of binary software.  Such

distribution is the redistribution of modified works of the software's

source code.  GPLv2~\S3 addresses the matter of creation and distribution of

binary versions.

Under GPLv2~\S3, binary versions may be created and distributed under the

terms of GPLv2~\S1--2, so all the material previously discussed applies

here.  However, GPLv2~\S3 must go a bit further.  Access to the software's

source code is an incontestable prerequisite for the exercise of the

fundamental freedoms to modify and improve the software.  Making even

the most trivial changes to a software program at the binary level is

effectively impossible.  GPLv2~\S3 must ensure that the binaries are never

distributed without the source code, so that these freedoms are passed

through the distribution chain.

GPLv2~\S3 permits distribution of binaries, and then offers three options for

distribution of source code along with binaries. The most common and the

least complicated is the option given under GPLv2~\S3(a).

\label{GPLv2s3a}

GPLv2~\S3(a) offers the option to directly accompany the source code alongside

the distribution of the binaries.  This is by far the most convenient

option for most distributors, because it means that the source-code

provision obligations are fully completed at the time of binary

distribution (more on that later).

Under GPLv2~\S3(a), the source code provided must be the ``corresponding source

code.''  Here ``corresponding'' primarily means that the source code

provided must be that code used to produce the binaries being distributed.

That source code must also be ``complete''.   GPLv2~\S3's penultimate paragraph

explains in detail what is meant by ``complete''.  In essence, it is all

the material that a programmer of average skill would need to actually use

the source code to produce the binaries she has received.  Complete source

is required so that, if the licensee chooses, she should be able to

exercise her freedoms to modify and redistribute changes.  Without the

complete source, it would not be possible to make changes that were

actually directly derived from the version received.

\label{GPLv2s3-build-scripts}

Furthermore, GPLv2~\S3 is defending against a tactic that has in fact been

seen in GPL enforcement.  Under GPL, if you pay a high price for

a copy of GPL'd binaries (which comes with corresponding source, of

course), you have the freedom to redistribute that work at any fee you

choose, or not at all.  Sometimes, companies attempt a GPL-violating

cozenage whereby they produce very specialized binaries (perhaps for

an obscure architecture).  They then give source code that does

correspond, but withhold the ``incantations'' and build plans they

used to make that source compile into the specialized binaries.

Therefore, GPLv2~\S3 requires that the source code include ``meta-material'' like

scripts, interface definitions, and other material that is used to

``control compilation and installation'' of the binaries.  In this

manner, those further down the distribution chain are assured that

they have the unabated freedom to build their own modified works

from the sources provided.

Software distribution comes in many

forms.  Embedded manufacturers, for example, have the freedom to put

GPL'd software into mobile devices with very tight memory and space

constraints.  In such cases, putting the source right alongside the

binaries on the machine itself might not be an option.  While it is

recommended that this be the default way that people comply with GPL, the

GPL does provide options when such distribution is unfeasible.

\label{GPLv2s3-medium-customarily}

GPLv2~\S3, therefore, allows source code to be provided on any physical

``medium customarily used for software interchange.''  By design, this

phrase covers a broad spectrum --- the phrase seeks to pre-adapt to

changes in  technology.  When GPLv2 was first published in June

1991, distribution on magnetic tape was still common, and CD was

relatively new.  By 2002, CD was the default.  By 2007, DVD's were the

default.  Now, it's common to give software on USB drives and SD cards.  This

language in the license must adapt with changing technology.

Meanwhile, the binding created by the word ``customarily'' is key.  Many

incorrectly believe that distributing binary on CD and source on the

Internet is acceptable.  In the corporate world in industrialized countries, it is indeed customary to

simply download a CDs' worth of data quickly.  However, even today in the USA, many computer users are not connected to the Internet, and most people connected

to the Internet still have limited download speeds.  Downloading

CDs full of data is not customary for them in the least.  In some cities

in Africa, computers are becoming more common, but Internet connectivity

is still available only at a few centralized locations.  Thus, the

``customs'' here are normalized for a worldwide userbase.  Simply

providing source on the Internet --- while it is a kind, friendly and

useful thing to do --- is not usually sufficient.

Note, however, a major exception to this rule, given by the last paragraph

of GPLv2~\S3. \emph{If} distribution of the binary files is made only on the

Internet (i.e., ``from a designated place''), \emph{then} simply providing

the source code right alongside the binaries in the same place is

sufficient to comply with GPLv2~\S3.

\medskip

As is shown above, under GPLv2~\S3(a), embedded manufacturers can put the

binaries on the device and ship the source code along on a CD\@.  However,

sometimes this turns out to be too costly.  Including a CD with every

device could prove too costly, and may practically (although not legally)

prohibit using GPL'd software. For this situation and others like it, GPLv2\S~3(b) is available.

\label{GPLv2s3b}

GPLv2~\S3(b) allows a distributor of binaries to instead provide a written

offer for source code alongside those binaries.  This is useful in two

specific ways.  First, it may turn out that most users do not request the

source, and thus the cost of producing the CDs is saved --- a financial

and environmental windfall.  In addition, along with a GPLv2~\S3(b) compliant

offer for source, a binary distributor might choose to \emph{also} give a

URL for source code.  Many who would otherwise need a CD with source might

turn out to have those coveted high bandwidth connections, and are able to

download the source instead --- again yielding environmental and financial

windfalls.

However, note that regardless of how many users prefer to get the

source online, GPLv2~\S3(b) does place lasting long-term obligations on the

binary distributor.  The binary distributor must be prepared to honor

that offer for source for three years and ship it out (just as they

would have had to do under GPLv2~\S3(a)) at a moment's notice when they

receive such a request.  There is real organizational cost here:

support engineers must be trained how to route source requests, and

source CD images for every release version for the last three years

must be kept on hand to burn such CDs quickly. The requests might not

even come from actual customers; the offer for source must be valid

for ``any third party''.

That phrase is another place where some get confused --- thinking again

that full public distribution of source is required.  The offer for source

must be valid for ``any third party'' because of the freedoms of

redistribution granted by GPLv2~\S\S1--2.  A company may ship a binary image

and an offer for source to only one customer.  However, under GPL, that

customer has the right to redistribute that software to the world if she

likes.  When she does, that customer has an obligation to make sure that

those who receive the software from her can exercise their freedoms under

GPL --- including the freedom to modify, rebuild, and redistribute the

source code.

GPLv2~\S3(c) is created to save her some trouble, because by itself GPLv2~\S3(b)

would unfairly favor large companies.  GPLv2~\S3(b) allows the

separation of the binary software from the key tool that people can use

to exercise their freedom. The GPL permits this separation because it is

good for re-distributors, and those users who turn out not to need the

source.  However, to ensure equal rights for all software users, anyone

along the distribution chain must have the right to get the source and

exercise those freedoms that require it.

Meanwhile, GPLv2~\S3(b)'s compromise primarily benefits companies that

distribute binary software commercially.  Without GPLv2~\S3(c), that benefit

would be at the detriment of the companies' customers; the burden of

source code provision would be unfairly shifted to the companies'

customers.  A customer, who had received binaries with a GPLv2~\S3(b)-compliant

offer, would be required under GPLv2 (sans GPLv2~\S3(c)) to acquire the source,

merely to give a copy of the software to a friend who needed it.  GPLv2~\S3(c)

reshifts this burden to entity who benefits from GPLv2~\S3(b).

GPLv2~\S3(c) allows those who undertake \emph{noncommercial} distribution to

simply pass along a GPLv2~\S3(b)-compliant source code offer.  The customer who

wishes to give a copy to her friend can now do so without provisioning the

source, as long as she gives that offer to her friend.  By contrast, if

she wanted to go into business for herself selling CDs of that software,

she would have to acquire the source and either comply via GPLv2~\S3(a), or

write her own GPLv2~\S3(b)-compliant source offer.

This process is precisely the reason why a GPLv2~\S3(b) source offer must be

valid for all third parties.  At the time the offer is made, there is no

way of knowing who might end up noncommercially receiving a copy of the

software.  Companies who choose to comply via GPLv2~\S3(b) must thus be

prepared to honor all incoming source code requests.  For this and the

many other additional necessary complications under GPLv2~\S\S3(b--c), it is

only rarely a better option than complying via GPLv2~\S3(a).

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

\chapter{GPL's Implied Patent Grant}

\label{gpl-implied-patent-grant}

We digress again briefly from our section-by-section consideration of GPLv2

to consider the interaction between the terms of GPL and patent law. The

GPLv2, despite being silent with respect to patents, actually confers on its

licensees more rights to a licensor's patents than those licenses that

purport to address the issue. This is the case because patent law, under

the doctrine of implied license, gives to each distributee of a patented

article a license from the distributor to practice any patent claims owned

or held by the distributor that cover the distributed article. The

implied license also extends to any patent claims owned or held by the

distributor that cover ``reasonably contemplated uses'' of the patented

article. To quote the Federal Circuit Court of Appeals, the highest court

for patent cases other than the Supreme Court:

\begin{quotation}

Generally, when a seller sells a product without restriction, it in

effect promises the purchaser that in exchange for the price paid, it will

not interfere with the purchaser's full enjoyment of the product

purchased. The buyer has an implied license under any patents of the

seller that dominate the product or any uses of the product to which the

parties might reasonably contemplate the product will be put.

\end{quotation}

Hewlett-Packard Co. v. Repeat-O-Type Stencil Mfg. Corp., Inc., 123 F.3d

1445, 1451 (Fed. Cir. 1997).

Of course, Free Software is licensed, not sold, and there are indeed

restrictions placed on the licensee, but those differences are not likely

to prevent the application of the implied license doctrine to Free

Software, because software licensed under the GPL grants the licensee the

right to make, use, and sell the software, each of which are exclusive

rights of a patent holder. Therefore, although the GPLv2 does not expressly

grant the licensee the right to do those things under any patents the

licensor may have that cover the software or its reasonably contemplated

uses, by licensing the software under the GPLv2, the distributor impliedly

licenses those patents to the GPLv2 licensee with respect to the GPLv2'd

software.

An interesting issue regarding this implied patent license of GPLv2'd

software is what would be considered ``uses of the [software] to which

the parties might reasonably contemplate the product will be put.'' A

clever advocate may argue that the implied license granted by GPLv2 is

larger in scope than the express license in other Free Software

licenses with express patent grants, in that the patent license

clause of many of those other Free  Software licenses are specifically 

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

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 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}

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

  Code~\S2-316} requires that disclaimers of warranty be ``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

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

  answered Kuhn's requests for case law that argues THIS IS INHERENTLY MORE

  CONSPICUOUS \textsc{Than this is}.}.

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.

GPLv2~\S11 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{GPL Version 3}

\label{GPLv3}

This chapter discusses the text of GPLv3.  Much of this material herein

includes text that was adapted (with permission) from text that FSF

originally published as part of the so-called ``rationale documents'' for the

various discussion drafts of GPLv3.

The FSF ran a somewhat public process to develop GPLv3, and it was the first

attempt of its kind to develop a Free Software license this way.  Ultimately,

RMS was the primary author of GPLv3, but he listened to feedback from all

sorts of individuals and even for-profit companies.  Nevertheless, in

attempting to understand GPLv3 after the fact, the materials available from

the GPLv3 process have a somewhat ``drinking from the firehose'' effect.

This chapter seeks to explain GPLv3 to newcomers, who perhaps are familiar

with GPLv2 and who did not participate in the GPLv3 process.

Those who wish to drink from the firehose and take a diachronic approach to

GPLv3 study by reading the step-by-step public drafting process of the GPLv3 (which

occurred from Monday 16 January 2006 through Monday 19 November 2007) should

visit \url{http://gplv3.fsf.org/}.

\section{Understanding GPLv3 As An Upgraded GPLv2}

Ultimately, GPLv2 and GPLv3 co-exist as active licenses in regular use.  As

discussed in Chapter~\ref{tale-of-two-copylefts}, GPLv1 was never regularly

used alongside GPLv2.  However, given GPLv2's widespread popularity and

existing longevity by the time GPLv3 was published, it is not surprising that

some licensors still prefer GPLv2-only or GPLv2-or-later.  GPLv3 gained major

adoption by many projects, old and new, but many projects have not upgraded

due to (in some cases) mere laziness and (in other cases) policy preference

for some of GPLv2's terms and/or policy opposition to GPLv3's terms.

Given this ``two GPLs world'' is reality, it makes sense to consider GPLv3 in

terms of how it differs from GPLv2.  Also, most of the best GPL experts in

the world must deal regularly with both licenses, and admittedly have decades

of experience with GPLv2 while the most experience with GPLv3 that's possible

is by default less than a decade.  These two factors usually cause even new

students of GPL to start with GPLv2 and move on to GPLv3, and this tutorial

follows that pattern.

Overall, the changes made in GPLv3 admittedly \textit{increased} the

complexity of the license.  The FSF stated at the start of the GPLv3 process

that they would have liked to oblige those who have asked for a simpler and

shorter GPL\@.  Ultimately, the FSF gave priority to making GPLv3 a better

copyleft license in the spirit of past GPL's.  Obsession for concision should

never trump software freedom.

The FSF had many different, important goals in seeking to upgrade to GPLv3.

However, one important goal that is often lost in the discussion of policy

minutia is a rather simple but important issue.  Namely, FSF sought to assure

that GPLv3 was more easily internationalized than GPLv2.  In particular, the

FSF sought to ease interpretation of GPL in other countries by replacement of

USA-centric\footnote{See Section~\ref{non-usa-copyright} of this tutorial for

  a brief discussion about non-USA copyright systems.}  copyright phrases and

wording with neutral terminology rooted in description of behavior rather

than specific statute.  As can be seen in the section-by-section discussion of

GPLv3 that follows, nearly every section had changes related to issues of

internationalization.

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

\label{GPLv3s0}

One of lawyers' most common complaints about GPLv2 is that defined terms in

the document appear throughout.  Most licenses define terms up-front.

However, the GPL was always designed both as a document that should be easily

understood both by lawyers and by software developers: it is a document

designed to give freedom to software developers and users, and therefore it

should be comprehensible to that constituency.

Interestingly enough, one coauthor of this tutorial who is both a lawyer and

a developer pointed out that in law school, she understood defined terms more

quickly than other law students precisely because of her programming

background.  For developers, having \verb0#define0 (in the C programming

language) or other types of constants and/or macros that automatically expand

in the place where they are used is second nature.  As such, adding a defined

terms section was not terribly problematic for developers, and thus GPLv3

adds one.  Most of these defined terms are somewhat straightforward and bring

forward better worded definitions from GPLv2.  Herein, this tutorial

discusses a few of the new ones.

GPLv3~\S0 includes definitions of five new terms not found in any form in

GPLv2: ``modify'' ``covered work'', ``propagate'', ``convey'', and

``Appropriate Legal Notices''. 

\subsection{Modify and the Work Based on the Program}

%  FIXME: I think we actually need to research the claim below that

%  ``derivative work'' as a term is unique to USA copyright law.  I have

%  heard German lawyers, for example, use the term extensively.  Is it also a

%  term perhaps under German law?  -- bkuhn

GPLv2 included a defined term, ``work based on the Program'', but also used

the term ``modify'' and ``based on'' throughout the license.  GPLv2's ``work

based on the Program'' definition made use of a legal term of art,

``derivative work'', which is peculiar to USA copyright

law\footnote{(Ironically, most criticism of USA-specific legal

terminology in GPLv2's ``work based on the Program'' definition historically

came not primarily from readers outside the USA, but from those within

it.  The FSF noted in that it did not generally agree with these

  views, and expressed puzzlement by the energy with which they were

  expressed, given the existence of many other, more difficult legal issues

  implicated by the GPL.  Nevertheless, the FSF argued that it made sense to

  eliminate usage of local copyright terminology to good effect.}.  GPLv2

always sought to cover all rights governed by relevant copyright law, in the

USA and elsewhere.

Even though differently-labeled concepts corresponding to the

derivative work are recognized in all copyright law systems, these

counterpart concepts might differ to some degree in scope and breadth from

the USA derivative work.  GPLv3 therefore takes the task of

internationalizing the license further by removing references to derivative

works and by providing a more globally useful definition.

GPLv3 drops all reference to USA ``derivative works'' and returns

to the base concept only: GPL covers the licensed work and all works where

copyright permission from the licensed work's copyright holder.

The new definitions returns to the common elements of copyright law.  Copyright

holders of works of software have the exclusive right to form new works by

modification of the original --- a right that may be expressed in various

ways in different legal systems.  GPLv3 operates to grant this right to

successive generations of users (particularly through the copyleft conditions

set forth in GPLv3~\S5, as described later in this tutorial in its

\S~\ref{GPLv3s5}).  Here in GPLv3~\S0, ``modify'' refers to basic copyright

rights, and then this definition of ``modify'' is used to define ``modified

version of'' and ``work based on'' as synonyms.

\subsection{The Covered Work}

GPLv3 uses a common license drafting technique of building upon simpler

definitions to make complex ones.  The Program is a defined term found

throughout GPLv2, and the word ``covered'' and the phrase ``covered by this

license'' are used in tandem with the Program in GPLv2, but not as part of a

definition.  GPLv3 offers a single term ``covered work'', which enables some

of the wording in GPLv3 to be simpler and clearer than its GPLv2

counterparts.

Next, to avoid locking GPLv3 into specific copyright statues, the GPLv3

defines two terms that are otherwise exotic to the language of international

copyright.

\subsection{Propagate}

To ``propagate'' a work covered by the license means any activity in a locale

that requires permission of copyright holders in that locale's legal system.

However, personal use or modification for personal use are activities explicitly

excluded from ``propagation'' \textit{regardless} of domestic copyright law.

The term ``propagate'' serves two purposes.  First, ``propagate'' provides a

simple and convenient means for distinguishing between the kinds of uses of a

work that GPL imposes conditions on and the kinds of uses that GPL does not

(for the most part) impose conditions on.

Second, ``propagate'' helps globalize GPL in its wording and effect:

``derivative work'' was in fact not the only term commonly used by local

copyright statutes.  A term like ``distribute'' (or its equivalent in

languages other than English) is also used in several national copyright

statutes.  Practical experience with GPLv2 revealed the awkwardness of using

the term ``distribution'' in a license intended for global use: the scope of

``distribution'' in the copyright context can differ from country to country.

The GPL never necessarily intended the specific meaning of ``distribution''

that exists under USA (or any other country's) copyright law.

Indeed, even within a single country and language, the term distribution may

be ambiguous; as a legal term of art, distribution varies significantly in

meaning among those countries that recognize it.  For example, comments

during GPLv3's drafting process indicated that in at least one country,

distribution may not include network transfers of software but may include

interdepartmental transfers of physical copies within an organization.

Meanwhile, the copyright laws of many countries, as well as certain

international copyright treaties, recognize ``making available to the

public'' or ``communication to the public'' as one of the exclusive rights of

copyright holders.

Therefore, the GPLv3 defines the term ``propagate'' by reference to activities

that require permission under ``applicable copyright law'', but excludes

execution and private modification from the definition.  GPLv3's definition

also gives examples of activities that may be included within ``propagation''

but it also makes clear that, under the copyright laws of a given country,

``propagation'' may include other activities as well.

Thus, propagation is defined by behavior, and not by categories drawn from

some particular national copyright statute.  This helps not only with

internationalization, but also factually-based terminology aids in

developers' and users' understanding of the GPL\@.