}

\end{center}

\end{titlepage}

\tableofcontents

\chapter{Preface}

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

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

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

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

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

real-world case studies of GPL enforcement matters.

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

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

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

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

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

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

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

under the terms of the GNU GPL (or who wish to do so in the future), and those

who wish to make use of existing GPL'd software in their enterprise.

Upon completion of this part of the tutorial, readers can expect

to have learned the following:

\begin{itemize}

  \item The freedom-defending purpose of various terms in the GNU GPLv2 and GPLv3.

  \item The differences between GPLv2 and GPLv3.

  \item The obligations when modifying GPLv2'd or GPLv3'd software.

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

  \item The business advantages that the GPL provides.

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

  \item How existing GPL'd software can be used in existing enterprises.

  \item The basics of LGPLv2.1 and LGPLv3, and how they

  \item The basics to begin understanding the complexities regarding

    derivative and combined works of software.

\end{itemize}

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

% END OF ABSTRACTS SECTION

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

% START OF DAY ONE COURSE

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

\chapter{What Is Software Freedom?}

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

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

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

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

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

\label{GPLv1}

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

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

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

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

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

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

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

\begin{quotation}

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

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

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

without modification, no matter who is publishing it.

\end{quotation}

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

discussing potential improvements or changes to Free Software.

Fair use is a doctrine established by the courts or by statute.  By

contrast, unregulated uses are those that are not covered by the statue

nor determined by a court to be covered, but are common and enjoyed by

many users.  An example of unregulated use is reading a printout of the

program's source code like an instruction book for the purpose of learning

how to be a better programmer.  The right to read something that you have

access to is and should remain unregulated and unrestricted.

\medskip

to run specifically by stating the following:

\begin{quote}

''The act of running the Program is not restricted.''

\end{quote}

Thus, users are explicitly given the freedom to run by GPLv2~\S0.

\medskip

The bulk of GPLv2~\S0 not yet discussed gives definitions for other terms used

throughout.  The only one worth discussing in detail is ``work based on

the Program''.  The reason this definition is particularly interesting is

not for the definition itself, which is rather straightforward, but

covered by GPL are much more common.  For example, copyright statutes

generally require permission from the copyright holder to grant explicit

permission to modify a work in any manner.  As discussed in the next chapter,

the GPL {\em does} grant such permission, but requires the modified work must

also be licensed under the terms of the GPL (and only GPL:

see\S~\label{GPLv2s6} in this tutorial).  Determining whether software was

modified is a substantially easier analysis than the derivative work

discussions and considerations in this chapter.

The question of derivative works, when and how they are made, is undoubtedly

an essential discussion in the interpretation and consideration of copyleft.

That is why this chapter was included in this tutorial.  However, as we

GPLv2, we must gain a sense of perspective: most GPL questions center around

questions of modification and distribution, not preparation of derivative

works.  Derivative work preparation is ultimately a small subset of the types

of modified versions of the software a developer might create, thus, while an

excessive focus on derivative works indulges us in the more exciting areas of

copyleft, we must keep a sense of perspective regarding their relative

importance.

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

\chapter{Modified Source and Binary Distribution}

\label{source-and-binary}

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

misconception mentioned earlier --- that all modified versions must be 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 re-distributors to license the whole work 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

a work based on 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

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

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

licensor may have that cover the software or its reasonably contemplated

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.

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

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)}}

  holder, and

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

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

infringement claims against the non-GPLv2-compliant party and

infringement of the patent, because the implied patent license only

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

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

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

\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

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.

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'

\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

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.

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}

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.

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

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

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.

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

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.

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\@.

As a further benefit, because ``propagation'' includes all

to run is confined to the \textit{unmodified} Program.  This confinement is

unfortunately necessary since Programs that do not qualify as a User Product

in GPLv3~\S6 (see \S~\ref{user-product} in this tutorial) might have certain

unfortunate restrictions on the freedom to run.\footnote{See

  \S~\ref{freedom-to-run} of this tutorial for the details on ``the freedom to

  run''.}

GPLv3~\S2\P2 distinguishes between activities of a licensee that are

permitted without limitation and activities that trigger additional

requirements.  Specifically, GPLv3~\S2\P2 guarantees the basic freedoms of

privately modifying and running the program.  While these basic freedoms were

generally considered a standard part of users' rights under GPLv2 as well,

direct analog to the first sentence of GPLv3~\S2\P2 in GPLv2

(See \S~\ref{gplv2-private-modification} of this tutorial for more on this issue.)

Also, GPLv3~\S2\P2 gives an explicit permission for a client to provide a

copy of its modified software to a contractor exclusively for that contractor

to modify it further, or run it, on behalf of the client.  However, the

client can \textit{only} exercise this control over its own copyrighted

changes to the GPL-covered program.  The parts of the program it obtained

from other contributors must be provided to the contractor with the usual GPL

freedoms.  Thus, GPLv3 permits users to convey covered works to contractors

operating exclusively on the users' behalf, under the users' direction and

control, and to require the contractors to keep the users' copyrighted

enforce or invoke rights arising under anticircumvention law.

These disclaimers by each licensor of any intention to use GPL'd software to

stringently control access to other copyrighted works should effectively

prevent any private or public parties from invoking DMCA-like laws against

users who escape technical restriction measures implemented by GPL'd

software.

\section{GPLv3~\S4: Verbatim Copying}

\label{GPLv3s4}

GPLv3~\S4 is a revision of GPLv2~\S1 (as discussed in \S~\ref{GPLv2s1} of

GPLv2~\S1, other than to use the new defined terms.

The only notable change, of ``a fee'' to ``any price or no price'', is in the

first sentence of GPLv3\S4\P2.  The GPLv2\S1\P1 means that the GPL permits

one to charge money for the distribution of software.  Despite efforts by

copyleft advocates to explain this in GPLv2 itself and in other documents,

there are evidently some people who still believe that GPLv2 allows charging

for services but not for selling copies of software and/or that the GPL

requires downloads to be gratis.  Perhaps this is because GPLv2 referred to

charging a ``fee''; the term ``fee'' is generally used in connection with

services.

GPLv2's wording also referred to ``the physical act of transferring.''  The

intention was to distinguish charging for transfers from attempts to impose

licensing fees on all third parties.  ``Physical'' might be read, however, as

suggesting ``distribution in a physical medium only''.

To address these two issues, GPLv3 says ``price'' in place of ``fee,'' and

removes the term ``physical.''

GPLv3~\S4 has also been revised from its corresponding section in GPLv2 in

Specifically, a distributor of verbatim copies of the program's source code

must obey any existing additional terms that apply to parts of the program

pursuant to GPLv3~\S7.  In addition, the distributor is required to keep

intact all license notices, including notices of such additional terms.

Finally, there is no harm in explicitly pointing out what ought to be

obvious: that those who convey GPL-covered software may offer commercial

services for the support of that software.

\section{GPLv3~\S5: Modified Source}

\label{GPLv3s5}

% FIXME:  probably mostly still right, needs some updates, though.

GPLv3~\S6(a--b) now apply specifically to distribution of object code in a

physical product.  Physical products include embedded systems, as well as

physical software distribution media such as CDs.  As in GPLv2~\S3 (discussed

in \S~\ref{GPLv2s3} of this tutorial), the distribution of object code may

either be accompanied by the machine-readable source code, or it may be

accompanied by a valid written offer to provide the machine-readable source

code.  However, unlike in GPLv2, that offer cannot be exercised by any third

party; rather, only those ``who possess the object code'' can exercise

the offer.  (Note that this is a substantial narrowing of requirements of

offer fulfillment, and is a wonderful counterexample to dispute claims that

% FIXME:  probably mostly still right, needs some updates, though.

GPLv3~\S6(b) further revises the requirements for the written offer to

provide source code. As before, the offer must remain valid for at least

three years. In addition, even after three years, a distributor of a product

containing GPL'd object code must offer to provide source code for as long as

the distributor also continues to offer spare parts or customer support for

the product model.  This is a reasonable and appropriate requirement; a

distributor should be prepared to provide source code if he or she is

prepared to provide support for other aspects of a physical product.

\end{enumerate}

During the GPLv3 drafting process, some questioned the necessity of GPLv3~\S7;

those critics suggested that it creates complexity that did not previously

exist.  However, by the time of GPLv3's drafting, many existing GPLv2'd

software packages already combined with various non-copylefted Free Software

licensed code that carried such additional terms.  Therefore, GPLv3~\S7 is

rationalized existing practices of those package authors and modifiers, since

it sets clear guidelines regarding the removal and addition of these

additional terms.  With its carefully limited list of allowed additional

requirements, GPLv3\S7 accomplishes additional objectives as well, since it

permits the expansion of the base of code available for GPL developers, while

include by default.

However, any other non-permissive additional terms apart from those stated

above are considered ``further'' restrictions which

\hyperref[GPLv3s10]{GPLv3~\S10} prohibits.  Furthermore, as a compliance

matter, if you add additional terms in accordance with GPLv3~\S7, you must

ensure that the terms are placed in the relevant source files or provide a

conspicuous notice about where to find the additional terms.

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

GPLv2 provided for automatic termination of the rights of a person who

strong, will cover few patents. 

GPLv3 therefore makes a partial concession

which would lead these companies to feel secure in doing the

distribution themselves. GPLv3~\S11

applies only to those distributors that have

modified the program.  The other changes we have made in sections 10 and

11 provide strengthened defenses against patent assertion and compensate

partly for this concession. 

Therefore, GPLv3~\S11 introduces the terms ``contributor'', ``contributor version'', and

``essential patent claims'', which are

Program, contributors include all the copyright holders for the Program,

other than copyright holders of material originally licensed under non-GPL

terms and later incorporated into a GPL-covered work.  The contributors are

therefore the initial GPLv3 licensors of the Program and all subsequent

upstream licensors who convey, under the terms of GPLv3~\S5, modified covered

works.

Thus, the ``contributor version'' includes the material the contributor has copied from the

upstream version that the contributor has modified.  GPLv3~\S11\P3

 does not apply to those that redistribute the program

without change.\footnote{An implied patent license from the distributor,

however, often arises.  See \S~\ref{gpl-implied-patent-grant} in this tutorial}

In other words, the ``contributor version'' includes not just