% {\cal I}

\newcommand{\gplusi}{$\mathcal{G\!\!+\!\!I}$}

\newcommand{\worki}{$\mathcal{I}$}

\newcommand{\workg}{$\mathcal{G}$}

\label{separate-and-independent}

It is certainly possible to take an existing independent work (called

\worki{}) and combine it with a GPL'd program (called \workg{}).  The

license of \worki{}, when it is distributed as a separate and independent

work, remains the prerogative of the copyright holder of \worki{}.

However, when \worki{} is combined with \workg{}, it produces a new work

that is the combination of the two (called \gplusi{}). The copyright of

this combined work, \gplusi{}, is held by the original copyright

holder of each of the two works.

In this case, GPLv2~\S2 lays out the terms by which \gplusi{} may be

distributed and copied.  By default, under copyright law, the copyright

holder of \worki{} would not have been permitted to distribute \gplusi{};

copyright law forbids it without the expressed permission of the copyright

holder of \workg{}. (Imagine, for a moment, if \workg{} were a proprietary

product --- would its copyright holders  give you permission to create and distribute

\gplusi{} without paying them a hefty sum?)  The license of \workg{}, the

GPL, states the  options for the copyright holder of \worki{}

who may want to create and distribute \gplusi{}.  GPL's pregranted

permission to create and distribute derivative works, provided the terms

of GPL are upheld, goes far above and beyond the permissions that one

would get with a typical work not covered by a copyleft license.  (Thus, to

say that this restriction is any way unreasonable is simply ludicrous.)

\medskip

The next phrase of note in GPLv2~\S2(b) is ``licensed \ldots at no charge.''

This phrase  confuses many.  The sloppy reader points out this as ``a

contradiction in GPL'' because (in their confused view) that clause of GPLv2~\S2 says that redistributors cannot

charge for modified versions of GPL'd software, but GPLv2~\S1 says that

they can.  Avoid this confusion: the ``at no charge'' \textbf{does not} prohibit redistributors from

charging when performing the acts governed by copyright

law,\footnote{Recall that you could by default charge for any acts not

governed by copyright law, because the license controls are confined

by copyright.} but rather that they cannot charge a fee for the

\emph{license itself}.  In other words, redistributors of (modified

and unmodified) GPL'd works may charge any amount they choose for

performing the modifications on contract or the act of transferring

the copy to the customer, but they may not charge a separate licensing

fee for the software.

GPLv2~\S2(b) further states that the software must ``be licensed \ldots to all

third parties.''  This too yields some confusion, and feeds the

misconception mentioned earlier --- that all modified versions must made

available to the public at large.  However, the text here does not say

that.  Instead, it says that the licensing under terms of the GPL must

extend to anyone who might, through the distribution chain, receive a copy

of the software.  Distribution to all third parties is not mandated here,

but GPLv2~\S2(b) does require redistributors to license the derivative works in

a way that extends to all third parties who may ultimately receive a

copy of the software.

In summary, GPLv2\ 2(b) says what terms under which the third parties must

receive this no-charge license.  Namely, they receive it ``under the terms

of this License'', the GPLv2.  When an entity \emph{chooses} to redistribute

a derivative work of GPL'd software, the license of that whole 

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

expended 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.

\section{GPLv2~\S3: Producing Binaries}

\label{GPL-Section-3}

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 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

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 derivative 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 derivative 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).

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.

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 derivative 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 infeasible.

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 GPLv22 was first published in June

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

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

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

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 redistributors, 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 who

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 (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 licenses are specifically limited to the

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

To the contrary, GPLv2's implied patent license grants the GPLv2 licensee a

patent license to do much more than just that because the 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 derivative 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 amongst 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 software program under the GPLv2, then it

cannot assert the patent against any party that takes a license to its

program under the GPLv2. However, if a party uses that program without

complying with the GPLv2, then Company \compA{} can assert, not just copyright

infringement claims against the non-GPLv2-compliant party, but also

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,

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 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

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.

% FIXME: integrate this into this section.

To our knowledge, no one has invoked this section to add an explicit

geographical distribution limitation since GPLv2 was released in 1991. We

have concluded that this provision is not needed and is not expected to be

needed in the future, and that it therefore should be removed.

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

\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 shout at you.  The

\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.

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{GPLv3}

\label{GPLv3}

This chapter discussed 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.

\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 in regular

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

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

some licensors have continued to prefer GPLv2-only or GPLv2-or-later as their

preferred license.  GPLv3 has 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.

Given this ``two GPLs'' world is the one we all live in, 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 of 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 do the job

that needs to be done to build a better copyleft.  Obsession for concision

should never trump software freedom.

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

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

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

However, 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 four new terms not found in any form in

GPLv2: ``covered work'', ``propagate'', ``convey'', and ``Appropriate Legal

Notices''.

While ``covered by this license'' is a phrase found in GPLv2, defining it

more complete in a single as ``covered work'' enables some of the wording in

GPLv3 to be simpler and clearer than its GPLv2 counterparts.

% FIXME: does propagate  definition still work the same way in final draft?

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 the GPL imposes conditions on and the kinds of uses that the GPL

does not (for the most part) impose conditions on.

Second, ``propagate'' furthers our goal of making the license as global as

possible in its wording and effect.  When a work is licensed under the GPL,

the copyright law of some particular country will govern certain legal issues

arising under the license.  A term like ``distribute'' or its equivalent in

languages other than English, is used in several national copyright statutes.

The scope of ``distribution'' in the copyright context can differ from

country to country.  The GPL does not seek to necessarily use the specific

meaning of ``distribution'' that exists under United States copyright law or

any other country's copyright law.

Therefore, the GPL 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.

% FIXME: paragraph number change , and more on Convey once definition comes.

The third paragraph of section 2 represents another effort to compensate for

variation in national copyright law.  We distinguish between propagation that

enables parties other than the licensee to make or receive copies, and other

forms of propagation.  As noted above, the meaning of ``distribution'' under

copyright law varies from country to country, including with respect to

whether making copies available to other parties (such as related public or

corporate entities) is ``distribution.'' ``Propagation,'' however, is a term

not tied to any statutory language.  Propagation that does not enable other

parties to make or receive copies --- for example, making private copies or

privately viewing the program --- is permitted unconditionally.  Propagation

that does enable other parties to make or receive copies is permitted as

``distribution,'' subject to the conditions set forth in sections 4--6.

% FIXME: Appropriate Legal Notices

\section{GPLv3~\S1: Understanding CCS}

% FIXME: Talk briefly about importance of CCS and reference compliance guide

% FIXME: reword source code a bit

% FIXME: CCS Coresponding Source updated to newer definition in later drafts

Keeping with the desire to ``round up'' definitions that were spread

throughout the text of GPLv2, the definition of CCS\footnote{Note that the

  preferred term by those who work with both GPLv2 and GPLv3 is ``Complete

  Corresponding Source'', abbreviated to ``CCS''.  Admittedly, the word

  ``complete'' no longer appears in GPLv3 (which uses the word ``all''

  instead).  However, both GPLv2 and the early drafts of GPLv3 itself used

  the word complete, and early GPLv3 drafts even included the phrase

  ``Complete Corresponding Source''.  Meanwhile, use of the acronym ``CCS''

  (sometimes, ``C&CS'') was so widespread among GPL enforcers that its use

  continues even though GPLv3-focused experts tend to say just the defined

  term of ``Corresponding Source''.}, or, as GPLv3 officially calls it,

``Corresponding Source'', is given in GPLv3~\S1\P4.  This definition is as

broad as necessary to protect users' exercise of their rights under the

GPL. We follow the definition with particular examples to remove any doubt

that they are to be considered Complete Corresponding Source Code. We wish to

make completely clear that a licensee cannot avoid complying with the

requirements of the GPL by dynamically linking an add-on component to the

original version of a program.

Though the definition of Complete Corresponding Source Code in the

second paragraph of section 1 is expansive, it is not sufficient to

protect users' freedoms in many circumstances.  For example, a GPL'd

program, or a modified version of such a program, might need to be

signed with a key or authorized with a code in order for it to run on

a particular machine and function properly. Similarly, a program that

produces digitally-restricted files might require a decryption code in

order to read the output.  

% FIXME: Standard Interface

% FIXME: System Libraries: it's in a different place and changed in later drafts

The final paragraph of section 1 revises the exception to the source code

distribution requirement in GPLv2 that we have sometimes called the system

library exception. This exception has been read to prohibit certain

distribution arrangements that we consider reasonable and have not sought to

prevent, such as distribution of gcc linked with a non-free C library that is

included as part of a larger non-free system. This is not to say that such

non-free libraries are legitimate; rather, preventing free software from

linking with these libraries would hurt free software more than it would hurt

proprietary software.

As revised, the exception has two parts. Part (a) rewords the GPLv2

exception for clarity but also removes the words ``unless that

component itself accompanies the executable.''  By itself, (a) would

be too permissive, allowing distributors to evade their

responsibilities under the GPL.  We have therefore added part (b) to

specify when a system library that is an adjunct of a major essential

operating system component, compiler, or interpreter does not trigger

the requirement to distribute source code.  The more low-level the

functionality provided by the library, the more likely it is to be

qualified for this exception.

\section{GPLv3~\S2: Basic Permissions}

% FIXME: phrase ``unmodified Program'' appears due to User Products exception

We have included the first sentence of section 2 to further internationalize

the GPL. Under the copyright laws of some countries, it may be necessary for

a copyright license to include an explicit provision setting forth the

duration of the rights being granted. In other countries, including the

United States, such a provision is unnecessary but permissible.

The first paragraph of section 2 also acknowledges that licensees under the

GPL enjoy rights of copyright fair use, or the equivalent under applicable

law. These rights are compatible with, and not in conflict with, the freedoms

that the GPL seeks to protect, and the GPL cannot and should not restrict

them.

% FIXME: propagate and convey

Section 2 distinguishes between activities of a licensee that are permitted

without limitation and activities that trigger additional requirements. The

second paragraph of section 2 guarantees the basic freedoms of privately

modifying and running the program. However, the right to privately modify and

run the program is terminated if the licensee brings a patent infringement

lawsuit against anyone for activities relating to a work based on the

program.

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

\label{GPLv3s3}

% FIXME: reference the section in DMCA about this, maybe already there in

%        GPLv2 section?

% FIXME: Wrong paragraph now.

The second paragraph of section 3 declares that no GPL'd program is part of