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.  Those who wish a to head to the firehose and take a diachronic

approach to GPLv3 study by reading the step-by-step public drafting process

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 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: verify this still matches final GPLv3 text.

% FIXME:  link to GPLv2 tutorial sections if possible and where appropriate.

GPLv3\~S1 retains GPLv2's definition of ``source code'' and adds an explicit

definition of ``object code'' as ``any non-source version of a work''.

Object code is not restricted to a narrow technical meaning and is to be

understood broadly as including any form of the work other than the preferred

form for making modifications to it.  Object code therefore includes any kind

of transformed version of source code, such as bytecode or minified

Javascript.  The definition of object code also ensures that licensees cannot

escape their obligations under the GPL by resorting to shrouded source or

obfuscated programming.

% 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

an effective technological protection measure, regardless of what the program

does. Ill-advised legislation in the United States and other countries has

prohibited circumvention of such technological measures. If a covered work is

distributed as part of a system for generating or accessing certain data, the

effect of this paragraph is to prevent someone from claiming that some other

GPL'd program that accesses the same data is an illegal circumvention.

\section{GPLv3~\S4: Verbatim Copying}

% FIXME: there appear to be minor changes here in later drafts, fix that.

Section 4 has been revised from its corresponding section in GPLv2 in light

of the new section 7 on license compatibility. A distributor of verbatim

copies of the program's source code must obey any existing additional terms

that apply to parts of the program. In addition, the distributor is required

to keep intact all license notices, including notices of such additional

terms.

\section{GPLv3~\S5: Modified Source}

% FIXME: 5(a) is slightly different in final version

Section 5 contains a number of changes relative to the corresponding section

in GPLv2. Subsection 5a slightly relaxes the requirements regarding notice of

changes to the program. In particular, the modified files themselves need no

longer be marked. This reduces administrative burdens for developers of

modified versions of GPL'd software.

Under subsection 5a, as in the corresponding provision of GPLv2, the notices

must state ``the date of any change,'' which we interpret to mean the date of

one or more of the licensee's changes.  The best practice would be to include

the date of the latest change.  However, in order to avoid requiring revision

of programs distributed under ``GPL version 2 or later,'' we have retained

the existing wording.

% FIXME:  It's now (b) and (c).  Also, ``validity'' of proprietary

%         relicensing?  Give me a break.  I'll fix that.

Subsection 5b is the central copyleft provision of the license.  It now

states that the GPL applies to the whole of the work.  The license must be

unmodified, except as permitted by section 7, which allows GPL'd code to be

combined with parts covered by certain other kinds of free software licensing

terms. Another change in subsection 5b is the removal of the words ``at no

charge,'' which was often misinterpreted by commentators.  The last sentence

of subsection 5b explicitly recognizes the validity of disjunctive

dual-licensing.

%  FIXME: 5d.  Related to Appropriatey Legal notices

% follows 5d now, call it the ``final paragraph''

The paragraph following subsection 5c has been revised for clarity, but the

underlying meaning is unchanged. When independent non-derivative sections are

distributed for use in a combination that is a covered work, the whole of the

combination must be licensed under the GPL, regardless of the form in which

such combination occurs, including combination by dynamic linking. The final

sentence of the paragraph adapts this requirement to the new compatibility

provisions of section 7.

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

Section 6 of GPLv3, which clarifies and revises GPLv2 section 3, requires

distributors of GPL'd object code to provide access to the corresponding

source code, in one of four specified ways. As noted above, ``object code''

in GPLv3 is defined broadly to mean any non-source version of a work.

packages themselves tend not to be transmitted through BitTorrent owing to

reduced demand. There generally will be too few participants downloading the

same source package at the same time to enable effective seeding and

distribution.

% FIXME: rewrite a bit.

We have made two changes that recognize and facilitate distribution of

covered works in object code form using BitTorrent or similar peer-to-peer

methods.  First, under new subsection 6e, if a licensee conveys such a work

using peer-to-peer transmission, that licensee is in compliance with section

6 so long as the licensee knows, and informs other peers where, the object

code and its Corresponding Source are publicly available at no charge under

subsection 6d.  The Corresponding Source therefore need not be provided

through the peer-to-peer system that was used for providing the binary.

Second, we have revised section 9 to make clear that ancillary propagation of

a covered work that occurs as part of the process of peer-to-peer file

transmission does not require acceptance, just as mere receipt and execution

of the Program does not require acceptance.  Such ancillary propagation is

permitted without limitation or further obligation.

% FIXME:  removing additional restrictions

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

Section 7 requires a downstream user of a covered work to preserve the

non-GPL terms covering the added parts just as they must preserve the GPL, as

long as any substantial portion of those parts is present in the user's

version.

% FIXME: minor rewrites needed

Section 7 points out that GPLv3 itself makes no assertion that an additional

requirement is enforceable by the copyright holder.  However, section 7 makes

clear that enforcement of such requirements is expected to be by the

termination procedure given in section 8 of GPLv3.

% FIXME: better context, etc.

Some have questioned whether section 7 is needed, and some have suggested

that it creates complexity that did not previously exist.  We point out to

those readers that there is already GPLv2-licensed code that carries

additional terms.  One of the objectives of section 7 is to rationalize

existing practices of program authors and modifiers by setting clear

guidelines regarding the removal and addition of such terms.  With its

carefully limited list of allowed additional requirements, section 7

accomplishes additional objectives, permitting the expansion of the base of

code available for GPL developers, while also encouraging useful

experimentation with requirements we do not include in the GPL itself.

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

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

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

copied, modified, sublicensed, or distributed a work in violation of the

license.  Automatic termination can be too harsh for those who have committed

an inadvertent violation, particularly in cases involving distribution of

large collections of software having numerous copyright holders.  A violator

who resumes compliance with GPLv2 would need to obtain forgiveness from all

copyright holders, but even to contact them all might be impossible.

% FIXME: needs to be updated to describe more complex termination

Section 8 of GPLv3 replaces automatic termination with a non-automatic

termination process.  Any copyright holder for the licensed work may opt to

terminate the rights of a violator of the license, provided that the

copyright holder has first given notice of the violation within 60 days of

its most recent occurrence. A violator who has been given notice may make

efforts to enter into compliance and may request that the copyright holder

agree not exercise the right of termination; the copyright holder may choose

to grant or refuse this request.

% FIXME: needs to be updated to describe more complex termination

If a licensee who is in violation of GPLv3 acts to correct the violation and

enter into compliance, and the licensee receives no notice of the past

violation within 60 days, then the licensee need not worry about termination

of rights under the license.

\section{GPLv3~\S9: Acceptance}

% FIXME

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

% FIXME

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

\label{GPLv3s11}

% FIXME:  probably needs a lot of work, these provisions changed over time.

GPLv3 adds a new section on licensing of patents. GPLv2 relies on an implied

patent license. The doctrine of implied license is one that is recognized

under United States patent law but may not be recognized in other

jurisdictions. We have therefore decided to make the patent license grant

explicit in GPLv3. Under section 11, a redistributor of a GPL'd work

automatically grants a nonexclusive, royalty-free and worldwide license for

any patent claims held by the redistributor, if those claims would be

infringed by the work or a reasonably contemplated use of the work.

% FIXME:  probably needs a lot of work, these provisions changed over time.

The patent license is granted both to recipients of the redistributed work

and to any other users who have received any version of the work. Section 11

therefore ensures that downstream users of GPL'd code and works derived from

GPL'd code are protected from the threat of patent infringement allegations

made by upstream distributors, regardless of which country's laws are held to

apply to any particular aspect of the distribution or licensing of the GPL'd

code.

% FIXME:  probably needs a lot of work, these provisions changed over time.

A redistributor of GPL'd code may benefit from a patent license that has been

granted by a third party, where the third party otherwise could bring a

patent infringement lawsuit against the redistributor based on the

distribution or other use of the code. In such a case, downstream users of

the redistributed code generally remain vulnerable to the applicable patent

claims of the third party. This threatens to defeat the purposes of the GPL,

for the third party could prevent any downstream users from exercising the

freedoms that the license seeks to guarantee.

% FIXME:  probably needs a lot of work, these provisions changed over time.

The second paragraph of section 11 addresses this problem by requiring the

redistributor to act to shield downstream users from these patent claims. The

requirement applies only to those redistributors who distribute knowingly

relying on a patent license. Many companies enter into blanket patent

cross-licensing agreements. With respect to some such agreements, it would

not be reasonable to expect a company to know that a particular patent

license covered by the agreement, but not specifically mentioned in it,

protects the company's distribution of GPL'd code.

% FIXME: does this still fit with the final retaliation provision?

This narrowly-targeted patent retaliation provision is the only form of

patent retaliation that GPLv3 imposes by its own force. We believe that it

strikes a proper balance between preserving the freedom of a user to run and

modify a program, and protecting the rights of other users to run, modify,

copy, and distribute code free from threats by patent holders. It is

particularly intended to discourage a GPL licensee from securing a patent

directed to unreleased modifications of GPL'd code and then suing the

original developers or others for making their own equivalent modifications.

Several other free software licenses include significantly broader patent

retaliation provisions. In our view, too little is known about the

consequences of these forms of patent retaliation. As we explain below,

section 7 permits distribution of a GPL'd work that includes added parts

covered by terms other than those of the GPL. Such terms may include certain

kinds of patent retaliation provisions that are broader than those of section

2.

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

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

The wording in the first sentence of section 12 has been revised

slightly to clarify that an agreement, such as a litigation settlement

agreement or a patent license agreement, is one of the ways in which

conditions may be ``imposed'' on a GPL licensee that may contradict the

conditions of the GPL, but which do not excuse the licensee from

compliance with those conditions.  This change codifies what has been

our interpretation of GPLv2.  

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

We have removed the limited severability clause of GPLv2 section 7 as a

matter of tactical judgment, believing that this is the best way to ensure

that all provisions of the GPL will be upheld in court. We have also removed

the final sentence of GPLv2 section 7, which we consider to be unnecessary.

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

% FIXME

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

\label{GPlv2s14}

% FIXME Say more

No substantive change has been made in section 14. The wording of the section

has been revised slightly to make it clearer.

% FIXME; proxy

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

No substantive changes have been made in sections 15 and 16.

% FIXME: more, plus 17

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

\chapter{The Lesser GPL}

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

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

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

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

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

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

into the world as possible, particular tactical considerations

regarding software freedom dictate different means. Extending the

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

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

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

software is Free Software realize that full copyleft does not best

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

designed as a solution for such situations.

\section{The First LGPL'd Program}

The first example that FSF encountered where such altered tactics were

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

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

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

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

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

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

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

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

make use of the C library.

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

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

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

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

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

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

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

Unlike existing GNU application software, however, the licensing

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

somewhat different. Applications released under GPL would never

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

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

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

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

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

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

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

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

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

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

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

glibc.

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

advocates, since it stops all proprietary software development on

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

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

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

vendors would see the excellent opportunity to license their C libraries

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

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

glibc, but the most popular proprietary one.

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

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

scenario. Furthermore, users of those proprietary applications would also

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

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

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

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

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

were released under a license that permitted proprietary applications

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

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

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

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

the C library.

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

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

restrictions on the licensing of glibc ensured that nearly all proprietary

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

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

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

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

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

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

helpful when studying the license.

\section{What's the Same?}

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

discussion of the LGPL, we will first eliminate the sections that are

identical, or that have the minor modification changing the word

``Program'' to ``Library.''

First, LGPLv2.1~\S1, the rules for verbatim copying of source, are

equivalent to those in GPLv2~\S1.

Second, LGPLv2.1~\S8 is equivalent GPLv2~\S4\@. In both licenses, this

section handles termination in precisely the same manner.

LGPLv2.1~\S9 is equivalent to GPLv2~\S5\@. Both sections assert that

the license is a copyright license, and handle the acceptance of those

copyright terms.

LGPLv2.1~\S10 is equivalent to GPLv2~\S6. They both protect the

distribution system of Free Software under these licenses, to ensure that

up, down, and throughout the distribution chain, each recipient of the

software receives identical rights under the license and no other

restrictions are imposed.

LGPLv2.1~\S11 is GPLv2~\S7. As discussed, it is used to ensure that

other claims and legal realities, such as patent licenses and court

judgments, do not trump the rights and permissions granted by these

licenses, and requires that distribution be halted if such a trump is

known to exist.

LGPLv2.1~\S12 adds the same features as GPLv2~\S8. These sections are

used to allow original copyright holders to forbid distribution in

countries with draconian laws that would otherwise contradict these

licenses.

LGPLv2.1~\S13 sets up FSF as the steward of the LGPL, just as GPLv2~\S9

does for GPL. Meanwhile, LGPLv2.1~\S14 reminds licensees that copyright

holders can grant exceptions to the terms of LGPL, just as GPLv2~\S10

reminds licensees of the same thing.

Finally, the assertions of no warranty and limitations of liability are

identical; thus LGPLv2.1~\S15 and LGPLv2.1~\S16 are the same as GPLv2~\S11 and \S

12.

As we see, the entire latter half of the license is identical.

The parts which set up the legal boundaries and meta-rules for the license

are the same. It is our intent that the two licenses operate under the