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.

GPLv3~\S6(a--b) clarifies that the medium for software interchange on which

the machine-readable source code is provided must be a durable physical

medium.  GPLv3~\S6(b)(2), however, permits a distributor to instead offer to

provide source code from a network server instead, which is yet another

example GPLv3 looser in its requirements than GPLv2 (see

\S~\ref{GPLv2s3-medium-customarily} for details).

% FIXME-LATER: more information about source provision, cost of physically

% performing, reasonable fees, medium customary clearly being said durable

% connecting back to previous text

GPLv3\S6(c) gives narrower permission than GPLv2\S3(c).  The ``pass along''

option for GPLv3\S6(c)(1) offers is now available only for individual

distribution of object code; moreover, such individual distribution can occur

only ``occasionally and noncommercially.''  A distributor cannot comply with

the GPL merely by making object code available on a publicly-accessible

network server accompanied by a copy of the written offer to provide source

code received from an upstream distributor.

%FIXME-LATER: tie back to the discussion of the occasional offer pass along

%             stuff in GPLv2 this tutorial.

GPLv3~\S6(d) revises and improves GPLv2~\S3's final paragraph.  When object

code is provided by offering access to copy the code from a designated place

(such as by enabling electronic access to a network server), the distributor

must merely offer equivalent access to copy the source code ``in the same way

through the same place''.  This wording also permits a distributor to offer a

third party access to both object code and source code on a single network

portal or web page, even though the access may include links to different

physical servers.  For example, a downstream distributor may provide a link

to an upstream distributor's server and arrange with the operator of that

server to keep the source code available for copying for as long as the

downstream distributor enables access to the object code.  This codifies

formally typical historical interpretation of GPLv2.

% FIXME-LATER: perhaps in enforcement section, but maybe here, note about

% ``slow down'' on source downloads being a compliance problem. 

Furthermore, under GPLv3~\S6(d), distributors may charge for the conveyed

object code; however, those who pay to obtain the object code must be given

equivalent and gratis access to obtain the CCS.  (If distributors convey the

object code gratis, distributors must likewise make CCS available without

charge.)  Those who do not obtain the object code from that distributors

(perhaps because they choose not to pay the fee for object code) are outside

the scope of the provision; distributors are under no specific obligation to

give CCS to someone who has not purchased an object code download under

GPLv3~\S6(d).  (Note: this does not change nor impact any obligations under

GPLv3~\S6(b)(2); GPLv3~\S6(d) is a wholly different provision.)

\subsection{GPLv3~\S6(e): Peer-to-Peer Sharing Networks}

Certain decentralized forms of peer-to-peer file sharing present a challenge

to the unidirectional view of distribution that is implicit in GPLv2 and

Draft 1 of GPLv3.  Identification of an upstream/downstream link in

BitTorrent distribution is neither straightforward nor reasonable; such

distribution is multidirectional, cooperative and anonymous.  In peer-to-peer

distribution systems, participants act both as transmitters and recipients of

blocks of a particular file, but they perceive the experience merely as users

and receivers, and not as distributors in any conventional sense.  At any

given moment of time, most peers will not have the complete file.

Meanwhile, GPLv3~\S6(d) permits distribution of a work in object code form

over a network, provided that the distributor offers equivalent access to

copy the Corresponding Source Code ``in the same way through the same

place''.  This wording might be interpreted to permit peer-to-peer

distribution of binaries \textit{if} they are packaged together with the CCS,

but such packaging impractical, for at least three reasons.  First, even if

the CCS is packaged with the object code, it will only be available to a

non-seeding peer at the end of the distribution process, but the peer will

already have been providing parts of the binary to others in the network.

Second, in practice, peer-to-peer forms of transmission are poorly suited

means for distributing CCS.  In large distributions, packaging CCS with the

object code may result in a substantial increase in file size and

transmission time.  Third, in current practice, CCS packages themselves tend

\textit{not} to be transmitted through BitTorrent --- owing to reduced demand

-- thus, there generally will be too few participants downloading the same

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

GPLv3~\S6(e) addresses this issues.  If a licensee conveys such a work of

object code using peer-to-peer transmission, that licensee is in compliance

with GPLv3~\S6 if the licensee informs other peers where the object code and

its CCS are publicly available at no charge under subsection GPLv3~\S6(d).

The CCS therefore need not be provided through the peer-to-peer system that

was used for providing the binary.

Second, GPLv3\S9 also clarifies 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-LATER: Would be nice to explain much more about interactions between

% the various options of GPLv3~\S6(a-e), which might all be in play at once!

\subsection{User Products, Installation Information and Device Lock-Down}

As discussed in \S~\ref{GPLv3-drm} of this tutorial, GPLv3 seeks thwart

technical measures such as signature checks in hardware to prevent

modification of GPL'd software on a device.

To address this issue, GPLv3~\S6 requires that parties distributing object

code provide recipients with the source code through certain means.  When

those distributors pass on the CCS, they are also required to pass on any

information or data necessary to install modified software on the particular

device that included it.  (This strategy is not unlike that used in LGPLv2.1

to enable users to link proprietary programs to modified libraries.)

% FIXME-LATER: LGPLv2.1 section should talk about this explicitly and this

%              should be a forward reference here

\subsubsection{User Products}

\label{user-product}

The scope of these requirements are narrow.  GPLv3~\S6 introduces the concept

of a ``User Product'', which includes devices that are sold for personal,

family, or household use.  Distributors are only required to provide

Installation Information when they convey object code in a User Product.

In brief, the right to convey object code in a defined class of ``User

Products,'' under certain circumstances, on providing whatever information is

required to enable a recipient to replace the object code with a functioning

modified version.

This was a compromise that was difficult for the FSF to agree to during the

GPLv3 drafting process.  However, companies and governments that use

specialized or enterprise-level computer facilities reported that they

actually \textit{want} their systems not to be under their own control.

Rather than agreeing to this as a concession, or bowing to pressure, they ask

for this as a \textit{preference}.  It is not clear that the GPL should interfere

here, since the main problem lies elsewhere.

While imposing technical barriers to modification is wrong regardless of

circumstances, the areas where restricted devices are of the greatest

practical concern today fall within the User Product definition.  Most, if

not all, technically-restricted devices running GPL-covered programs are

consumer electronics devices.  Moreover, the disparity in clout between the

manufacturers and these users makes it difficult for the users to reject

technical restrictions through their weak and unorganized market power.  Even

limited to User Products, this provision addresses the fundamental problem.

% FIXME-LATER: link \href to USC 2301

The core of the User Product definition is a subdefinition of ``consumer

product'' adapted from the Magnuson-Moss Warranty Act, a federal

consumer protection law in the USA found in 15~USC~\S2301: ``any tangible

personal property which is normally used for personal, family, or household

purposes.''  The USA has had three decades of experience of liberal

judicial and administrative interpretation of this definition in a manner

favorable to consumer rights.\footnote{The Magnuson-Moss consumer product

  definition itself has been influential in the USA and Canada, having been

  adopted in several state and provincial consumer protection laws.}

Ideally, this body of interpretation\footnote{The FSF, however, was very

  clear that incorporation of such legal interpretation was in no way

  intended work as a general choice of USA law for GPLv3.} will guide

interpretation of the consumer product subdefinition in GPLv3~\S6, and this

will hopefully provide a degree of legal certainty advantageous to device

manufacturers and downstream licensees alike.

One well-established interpretive principle under Magnuson-Moss is that

ambiguities are resolved in favor of coverage.  That is, in cases where

it is not clear whether a product falls under the definition of consumer

product, the product will be treated as a consumer product.\footnote{16

CFR~\S\ 700.1(a); \textit{McFadden v.~Dryvit Systems, Inc.}, 54

UCC~Rep.~Serv.2d 934 (D.~Ore.~2004).}  Moreover, for a given product,

``normally used'' is understood to refer to the typical use of that type

of product, rather than a particular use by a particular buyer.

Products that are commonly used for personal as well as commercial

purposes are consumer products, even if the person invoking rights is a

commercial entity intending to use the product for commercial

purposes.\footnote{16 CFR \S \ 700.1(a).  Numerous court decisions

interpreting Magnuson-Moss are in accord; see, e.g., \textit{Stroebner

Motors, Inc.~v.~Automobili Lamborghini S.p.A.}, 459 F.~Supp.2d 1028,

1033 (D.~Hawaii 2006).}  Even a small amount of ``normal'' personal use

is enough to cause an entire product line to be treated as a consumer

product under Magnuson-Moss\footnote{\textit{Tandy Corp.~v.~Marymac

Industries, Inc.}, 213 U.S.P.Q.~702 (S.D.~Tex.~1981). In this case, the

court concluded that TRS-80 microcomputers were consumer products, where

such computers were designed and advertised for a variety of users,

including small businesses and schools, and had only recently been

promoted for use in the home.}.

However, Magnuson-Moss is not a perfect fit because in the area of components

of dwellings, the settled interpretation under Magnuson-Moss under-inclusive.

Depending on how such components are manufactured or sold, they may or may

not be considered Magnuson-Moss consumer products.\footnote{Building

  materials that are purchased directly by a consumer from a retailer, for

  improving or modifying an existing dwelling, are consumer products under

  Magnuson-Moss, but building materials that are integral component parts of

  the structure of a dwelling at the time that the consumer buys the dwelling

  are not consumer products. 16 C.F.R.~\S\S~700.1(c)--(f); Federal Trade

  Commission, Final Action Concerning Review of Interpretations of

  Magnuson-Moss Warranty Act, 64 Fed.~Reg.~19,700 (April 22, 1999); see also,

  e.g., \textit{McFadden}, 54 U.C.C.~Rep.~Serv.2d at 934.}  Therefore, GPLv3

defines User Products as a superset of consumer products that also includes

``anything designed or sold for incorporation into a dwelling.''

Thus, the three sentences in the center of GPLv3's User Product definition

encapsulate the judicial and administrative principles established over the

past three decades in the USA concerning the Magnuson-Moss consumer product

definition.  First, it states that doubtful cases are resolved in favor of

coverage under the definition.  Second, it indicate that the words ``normally

used'' in the consumer product definition refer to a typical or common use of

a class of product, and not the status of a particular user or expected or

actual uses by a particular user.  Third, it clearly states that the

existence of substantial non-consumer uses of a product does not negate a

determination that it is a consumer product, unless such non-consumer uses

represent the only significant mode of use of that product.

It should be clear from these added sentences that it is the general mode of

use of a product that determines objectively whether or not it is a consumer

product.  One could not escape the effects of the User Products provisions by

labeling what is demonstrably a consumer product in ways that suggest it is

``for professionals'', for example.

\subsubsection{Installation Information}

With the User Products definition complete,  The ``Installation Information''

definition uses that to define what those receiving object code inside a User

Product must receive.

Installation Information is information that is ``required to install and

execute modified versions of a covered work \dots from a modified version of

its'' CCS, in the same User Product for which the covered work is conveyed.

GPLv3 provides guidance concerning how much information must be provided: it

``must suffice to ensure that the continued functioning of the modified

object code is in no case prevented or interfered with solely because

modification has been made.''  For example, the information provided would be

insufficient if it enabled a modified version to run only in a disabled

fashion, solely because of the fact of modification (regardless of the actual

nature of the modification).  The information need not consist of

cryptographic keys; Installation Information may be ``any methods,

procedures, authorization keys, or other information''.

Note that GPLv3 does not define ``continued functioning'' further.  However,

GPLv3 does provide some additional guidance concerning the scope of

GPLv3-compliant action or inaction that distributors of

technically-restricted User Products can take with respect to a downstream

recipient who replaces the conveyed object code with a modified version.

First of all, GPLv3 makes clear that GPLv3 implies no obligation ``to

continue to provide support service, warranty, or updates'' for such a work.

Second, most technically-restricted User Products are designed to communicate

across networks.  It is important for both users and network providers to

know when denial of network access to devices running modified versions

becomes a GPL violation.  GPLv3 permits denial of access in two cases: ``when

the modification itself materially and adversely affects the operation of the

network,'' and when the modification itself ``violates the rules and

protocols for communication across the network''.  The second case is

deliberately drawn in general terms, and it serves as a foundation for

reasonable enforcement policies that respect recipients' right to modify

while recognizing the legitimate interests of network providers.

Note that GPLv3 permits the practice of conveying object code in a mode not

practically susceptible to modification by any party, such as code burned in

ROM or embedded in silicon.  The goal of the Installation Information

requirement is to ensure the downstream licensee receives the real right to

modify when the device manufacturer or some other party retains that right.

Accordingly, GPLv3\S6's ante-penultimate paragraph states that the

requirement to provide Installation Information ``does not apply if neither

you nor any third party retains the ability to install modified object code

on the User Product''.

Finally, GPLv3\S6 makes it clear that there is also no requirement to

provide warranty or support for the User Product itself.

\subsection{GPLv3~\S7: Additional Permissions}

\label{GPLv3s7}

The GPL is a statement of permissions, some of which have conditions.

Additional terms --- terms that supplement those of the GPL --- may come to be

placed on, or removed from, GPL-covered code in certain common ways.

Copyleft licensing theorists have generally called

 those added terms ``additional permissions'' if they grant

exceptions from the conditions of the GPL, and ``additional requirements'' if

they add conditions to the basic permissions of the GPL\@. The treatment of

additional permissions and additional requirements under GPLv3 is necessarily

asymmetrical, because they do not raise the same interpretive

issues; in particular, additional requirements, if allowed without careful

limitation, could transform a GPL'd program into a non-free one.

With these principles in the background, GPLv3~\S7  answers the following

questions: 

\begin{enumerate}

\item How do the presence of additional terms on all or part of a GPL'd program

affect users' rights?

\item When and how may a licensee add terms to code being

distributed under the GPL? 

\item When may a licensee remove additional terms?

\end{enumerate}

Additional permissions present the easier case.  Since the mid-1990s,

permissive exceptions often appeared alongside GPLv2 to allow combination

with certain non-free code.  Typically, downstream

stream recipients could remove those exceptions and operate under pure GPLv2.

Similarly, LGPLv2.1 is in essence a permissive variant of GPLv2,

and it permits relicensing under the GPL\@.  

These practices are now generalized via GPLv3~\S7.

A licensee may remove any additional permission from

a covered work, whether it was placed by the original author or by an

upstream distributor.  A licensee may also add any kind of additional

permission to any part of a work for which the licensee has, or can give,

appropriate copyright permission. For example, if the licensee has written

that part, the licensee is the copyright holder for that part and can

therefore give additional permissions that are applicable to it.

Alternatively, the part may have been written by someone else and licensed,

with the additional permissions, to that licensee.  Any additional

permissions on that part are, in turn, removable by downstream recipients.

As GPLv3~\S7\P1 explains, the effect of an additional permission depends on

whether the permission applies to the whole work or a part.

% FIXME-LATER: LGPLv3 will have its own section

Indeed, LGPLv3 is itself simply  a list of additional permissions supplementing the

terms of GPLv3.  GPLv3\S7 has thus provided the basis for recasting a

formally complex license as an elegant set of added terms, without changing

any of the fundamental features of the existing LGPL\@.  LGPLv3 is thus  a model for developers wishing to license their works under the

GPL with permissive exceptions.  The removability of additional permissions

under GPLv3\S7 does not alter any existing behavior of the LGPL since the LGPL

has always allowed relicensing under the ordinary GPL\@.

\section{GPLv3~\S7: Understanding License Compatibility}

\label{license-compatibility}

A challenge that faced the Free Software community heavily through out the

early 2000s was the proliferation of incompatible Free Software licenses.  Of

course, the GPL cannot possibly be compatible with all such licenses.

However, GPLv3

contains provisions that are designed to reduce license incompatibility by

making it easier for developers to combine code carrying non-GPL terms with

GPL'd code.

This license compatibility issue arises for

three reasons.  First, the GPL is a strong copyleft license, requiring

modified versions to be distributed under the GPL\@.  Second, the GPL states

that no further restrictions may be placed on the rights of recipients.

Third, all other software freedom respecting licenses in common contain certain

requirements, many of which are not conditions made by the GPL\@.  Thus, when

GPL'd code is modified by combination with code covered by another formal

license that specifies other requirements, and that modified code is then

distributed to others, the freedom of recipients may be burdened by

additional requirements in violation of the GPL.  It can be seen that

additional permissions in other licenses do not raise any problems of license

compatibility.

GPLv3  took a new approach to the issue of combining GPL'd code with

code governed by the terms of other software freedom licenses.  Traditional

GPLv2 license compatibility theory (which was not explicitly stated in GPLv2

itself, but treated as a license interpretation matter by the FSF) held that GPLv2 allowed such

combinations only if the non-GPL licensing terms permitted distribution under

the GPL and imposed no restrictions on the code that were not also imposed by

the GPL\@.  In practice, the FSF historically supplemented that policy with a structure of

exceptions for certain kinds of combinations.

GPLv3~\S7  implements a more explicit policy on license

compatibility.  It formalizes the circumstances under which a licensee may

release a covered work that includes an added part carrying non-GPL terms. 

GPLv3~\S7 distinguish between terms that provide additional permissions, and terms that

place additional requirements on the code, relative to the permissions and

requirements established by applying the GPL to the code.

As discussed in the previous section of this tutorial, GPLv3~\S7 first and foremost explicitly allows added parts covered by terms with

additional permissions to be combined with GPL'd code. This codifies the

existing practice of regarding such licensing terms as compatible with the

GPL\@. A downstream user of a combined GPL'd work who modifies such an added

part may remove the additional permissions, in which case the broader

permissions no longer apply to the modified version, and only the terms of

the GPL apply to it.

In its treatment of terms that impose additional requirements, GPLv3\S7

extends the range of licensing terms with which the GPL is compatible.  An

added part carrying additional requirements may be combined with GPL'd code,

but only if those requirements belong to an set enumerated in GPLv3\S7. There

ensures that enhanced license compatibility does not

defeat the broader software-freedom-defending terms of the GPL\@. Unlike terms that grant

additional permissions, terms that impose additional requirements cannot be

removed by a downstream user of the combined GPL'd work, because only in the

pathological case\footnote{Theoretically, a user could collect copyright

  assignment from all known contributors and then do this, but this would

  indeed be the pathological case.}  would a user have the right to do so.

% FIXME-LATER: It would be good to have detailed info on each of 7a-f.

%              Here's some commented-out text that might be useful for 7a-b

%% Under subsections 7a and 7b, the requirements may include preservation of

%% copyright notices, information about the origins of the code or alterations

%% of the code, and different warranty disclaimers. Under subsection 7c, the

%% requirements may include limitations on the use of names of contributors and

%% on the use of trademarks for publicity purposes. In general, we permit these

%% requirements in added terms because many free software licenses include them

%% and we consider them to be unobjectionable. Because we support trademark fair

%% use, the limitations on the use of trademarks may seek to enforce only what

%% is required by trademark law, and may not prohibit what would constitute fair

%% use.

% FIXME-LATER:  Say removing additional restrictions

% FIXME-LATER: This text may be useful later:

%% 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}

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 technically needs to obtain forgiveness

from all copyright holders, and even contacting them all might be impossible.

reinstatement of rights. The termination procedure provides a limited

opportunity to cure license violations.  If a licensee has committed a

first-time violation of the GPL with respect to a given copyright holder, but

the licensee cures the violation within 30 days following receipt of notice

of the violation, then any of the licensee's GPL rights that have been

terminated by the copyright holder are ``automatically reinstated''.

Finally, if a licensee violates the GPL, a contributor may terminate any

patent licenses that it granted under GPLv3~\S11, in addition to any

copyright permissions the contributor granted to the licensee.

% FIXME-LATER: write more here, perhaps linking up to enforcement

\section{GPLv3~\S9: Acceptance}

GPLv3~\S9 means what it says: mere receipt or execution of code neither

requires nor signifies contractual acceptance under the GPL.  Speaking more

broadly, GPLv3 is intentionally structured our license as a unilateral grant

of copyright permissions, the basic operation of which exists outside of any

law of contract.  Whether and when a contractual relationship is formed

between licensor and licensee under local law do not necessarily matter to

the working of the license.

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

% FIXME-LATER: this is a punt: need more time to write!

GPLv3~\S10 ensures that everyone downstream receives licenses from all

copyright holders.  It really is a generally straightforward section.

% FIXME-LATER: link up this paragraph to above sections.

Note, however, GPLv3 removed the words ``at no charge'' from GPLv2~\S2(b) (in

GPLv3,~\S5(b)) because it contributed to a misconception that the GPL did not

permit charging for distribution of copies.  The purpose of the ``at no

charge'' wording was to prevent attempts to collect royalties from third

parties.  The removal of these words created the danger that the imposition

of licensing fees would no longer be seen as a license violation.  Therefore,

GPLv3~\S10 adds a new explicit prohibition on imposition of licensing fees or

royalties.  This section is an appropriate place for such a clause, since it

is a specific consequence of the general requirement that no further

restrictions be imposed on downstream recipients of GPL-covered code.

% FIXME-LATER: This text needs further study before I can conclude it belongs

% in this tutorial:

%% Careful readers of the GPL have suggested that its explicit prohibition

%% against imposition of further restrictions\footnote{GPLv2, section 6; Draft

%%   3, section 10, third paragraph.} has, or ought to have, implications for

%% those who assert patents against other licensees.  Draft 2 took some steps to

%% clarify this point in a manner not specific to patents, by describing the

%% imposition of ``a license fee, royalty, or other charge'' for exercising GPL

%% rights as one example of an impermissible further restriction.  In Draft 3 we

%% have clarified further that the requirement of non-imposition of further

%% restrictions has specific consequences for litigation accusing GPL-covered

%% programs of infringement.  Section 10 now states that ``you may not initiate

%% litigation (including a cross-claim or counterclaim in a lawsuit) alleging

%% that any patent claim is infringed by making, using, selling, offering for

%% sale, or importing the Program (or the contribution of any contributor).''

%% That is to say, a patent holder's licensed permissions to use a work under

%% GPLv3 may be terminated under section 8 if the patent holder files a lawsuit

%% alleging that use of the work, or of any upstream GPLv3-licensed work on

%% which the work is based, infringes a patent.

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

\label{GPLv3s11}

Software patenting is a harmful and unjust policy, and should be abolished;

recent experience makes this all the more evident. Since many countries grant

patents that can apply to and prohibit software packages, in various guises

and to varying degrees, GPLv3 seeks to protect the users of GPL-covered programs

from those patents, while at the same time making it feasible for patent

holders to contribute to and distribute GPL-covered programs as long as they

do not attack the users of those programs.

It is generally understood that GPLv2 implies some limits on a licensee's

power to assert patent claims against the use of GPL-covered works.

However, the patent licensing practices that GPLv2~\S7 (corresponding to

GPLv3~\S12) is designed to prevent is only one of several ways in which

software patents threaten to make free programs non-free and to prevent users

from exercising their rights under the GPL. GPLv3 takes a more comprehensive

approach to combating the danger of patents.

GPLv2~\S7 has seen some success in deterring conduct that would otherwise

result in denial of full downstream enjoyment of GPL rights, and thus it is

preserved in GPLv3~\S12.  Experience has shown that more is necessary,

however, to ensure adequate community safety where companies act in concert

to heighten the anticompetitive use of patents that they hold or license.

Therefore,  GPLv3 is designed to reduce the patent risks that distort and

threaten the activities of users who make, run, modify and share Free

Software.  At the same time, GPLv3 gives favorable consideration to practical

goals such as certainty and administrability for patent holders that

participate in distribution and development of GPL-covered software.  GPLv3's

policy requires each such patent holder to provide appropriate levels of

patent assurance to users, according to the nature of the patent holder's

relationship to the program.

\subsection{The Contributor's Explicit Patent License}

Specifically, the ideal might have been for GPLv3 to feature a patent license

grant triggered by all acts of distribution of GPLv3-covered works.  The FSF

considered it during the GPLv3 drafting process, but many patent-holding

companies objected to this policy.  They have made two objections: (1) the

far-reaching impact of the patent license grant on the patent holder is

disproportionate to the act of merely distributing code without modification

or transformation, and (2) it is unreasonable to expect an owner of vast

patent assets to exercise requisite diligence in reviewing all the

GPL-covered software that it provides to others.  Some expressed particular

concern about the consequences of ``inadvertent'' distribution.

The argument that the impact of the patent license grant would be

``disproportionate'',  that is to say unfair, is not valid. Since

software patents are weapons that no one should have, and using them for

aggression against free software developers is an egregious act (thus

preventing that act cannot be unfair). 

However, the second argument seems valid in a practical sense.  A

typical GNU/Linux distribution includes thousands of programs.  It would

be quite difficult for a redistributor with a large patent portfolio to

review all those programs against that portfolio every time it receives

and passes on a new version of the distribution.  Moreover, this question

raises a strategic issue. If the GPLv3 patent license requirements

convince patent-holding companies to remain outside the distribution

path of all GPL-covered software, then these requirements, no matter how

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

used in the GPLv3~\S11\P3.   Viewed from the perspective of a recipient of the

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

the material added or altered by the contributor, but also the pre-existing

material the contributor copied from the upstream version and retained in the

modified version.  (GPLv3's usage of ``contributor'' and ``contribution'' should

not be confused with the various other ways in which those terms are used in

certain other free software licenses\footnote{Cf., e.g., Apache License,

  version 2.0, section 1; Eclipse Public License, version 1.0, section 1;

  Mozilla Public License, version 1.1, section 1.1.}.)

Some details of the ``essential patent claims'' definition deserve special

mention.  ``Essential patent claims'', for a given party, are a subset of the

claims ``owned or controlled'' by the party.  They do include sublicensable

claims that have been licensed to the contributor by a third

party.\footnote{This issue is typically handled in other software freedom

  licenses having patent licensing provisions by use of the unhelpful term

  ``licensable,'' which is either left undefined or is given an ambiguous

  definition.}  Most commercial patent license agreements that permit

sublicensing do so under restrictive terms that are inconsistent with the

requirements of the GPL\@.  For example, some patent licenses allow the

patent licensee to sublicense but require collection of royalties from any

sublicensees.  The patent licensee could not distribute a GPL-covered program

and grant the recipient a patent sublicense for the program without violating

section 12 of GPLv3.\footnote{GPLv3 also provides an example in section 12

  that makes this point clear.}  In rare cases, however, a conveying party

can freely grant patent sublicenses to downstream recipients without

violating the GPL\@.

Additionally, ``essential patent claims'' are those patents ``that would be

infringed by some manner, permitted by this License, of making, using, or

selling the work''.  This intends to make clear that a patent claim is

``essential'' if some mode of usage would infringe that claim, even if there

are other modes of usage that would not infringe.

Finally, ``essential patent claims \ldots do not include

claims that would be infringed only as a consequence of further

modification of the work.''  The set of essential patent

claims licensed  is fixed by the

the particular version of the work that was contributed.  The claim set

cannot expand as a work is further modified downstream.  (If it could,

then any software patent claim would be included, since any software

patent claim can be infringed by some further modification of the

work.)\footnote{However, ``the work'' should not be understood to be

restricted to a particular mechanical affixation of, or medium for

distributing, a program, where the same program might be provided in

other forms or in other ways that may be captured by other patent claims

held by the contributor.}

\medskip

Ideally, this contributor patent policy will result in fairly frequent licensing of patent

claims by contributors.  A contributor is charged with awareness of the fact

that it has modified a work and provided it to others; no act of contribution

should be treated as inadvertent.  GPLv3's rule also requires no more work, for a

contributor, than the weaker rule proposed by the patent holders.  Under

their rule, the contributor must always compare the entire work against its

patent portfolio to determine whether the combination of the modifications

with the remainder of the work cause it to read on any of the contributor's

patent claims.

\subsection{Conveyors' Patent Licensing}

The remaining patent licensing in GPLv3 deals with patent licenses that are

granted by conveyance.  The licensing is not as complete or far reaching at

the contributor patent licenses discussed in the preceding section.

The term ``patent license,'' as used in GPLv3~\S11\P4--6, is not meant to be

confined to agreements formally identified or classified as patent licenses.

GPLv3~\S11\P3  makes this clear by defining ``patent

license,'' for purposes of the subsequent three paragraphs, as ``any express

agreement or commitment, however denominated, not to enforce a patent

(such as an express permission to practice a patent or covenant not to

sue for patent infringement)''

% FIME-LATER: I want to ask Fontana about this before adding it.

% The definition does not include patent licenses that arise by

% implication or operation of law, because the third through fifth paragraphs

% of section 11 are specifically concerned with explicit promises that purport

% to be legally enforceable.

GPLv3~\S11\P5 is commonly called GPLv3's downstream shielding provision.  It

responds particularly to the problem of exclusive deals between patent

holders and distributors, which threaten to distort the free software

distribution system in a manner adverse to developers and users.  The

fundamental idea is to make a trade-off between assuring a patent license for

downstream and making  (possibly patent-encumbered) CCS publicly available.

Simply put, in nearly all cases in which the ``knowingly relying'' test is

met, the patent license will indeed not be sublicensable or generally

available to all on free terms.  If, on the other hand, the patent license is

generally available under terms consistent with the requirements of the GPL,

the distributor is automatically in compliance, because the patent license

has already been extended to all downstream recipients.  Finally, if the

patent license is sublicensable on GPL-consistent terms, the distributor may

choose to grant sublicenses to downstream recipients instead of causing the

CCS to be publicly available.  (In such a case, if the distributor is also a

contributor, it will already have granted a patent sublicense anyway, and so

it need not do anything further to comply with the third paragraph.)

Admittedly, public disclosure of CCS is not necessarily required in by other

sections of the GPL, and the FSF in drafting GPLv3 did not necessarily wish

to impose a general requirement to make source code available to all, which

has never been a GPL condition.  However, many vendors who produce products

that include copylefted software, and who most likely to be affected by the

downstream shielding provision, lobbied for the addition of the source code

availability option, so it remains.

Meanwhile, two specific alternatives to the source code availability option

are also available. The distributor may comply by disclaiming the patent

license it has been granted for the conveyed work, or by arranging to extend

the patent license to downstream recipients\footnote{The latter option, if

  chosen, must be done ``in a manner consistent with the requirements of this

  License''; for example, it is unavailable if extension of the patent

  license would result in a violation of GPLv3~\S 12.}.  The GPL is intended

to permit private distribution as well as public distribution, and the

addition of these options ensures that this remains the case, even though it

remains likely that distributors in this situation will usually choose the

source code availability option.

Note that GPLv3~\S11\P5 is activated only if the CCS is not already otherwise

publicly available.  (Most often it will, in fact, already be available on

some network server operated by a third party.)  Even if it is not already

available, the option to ``cause the Corresponding Source to be so

available'' can then be satisfied by verifying that a third party has acted

to make it available.  That is to say, the affected distributor need not

itself host the CCS to take advantage of the source code availability option.

This subtlety may help the distributor avoid certain peculiar assumptions of

liability.

Note that GPLv3~\S11\P6--7 are designed to stop distributors from colluding with

third parties to offer selective patent protection.  GPLv3 is designed to

ensure that all users receive the same rights; arrangements that circumvent

this make a mockery of free software, and we must do everything in our power

to stop them.

First, GPLv3~\S11\P6 states that any license that protects some recipients of

GPL'd software must be extended to all recipients of the software.  

If conveyors arrange to provide patent

protection to some of the people who get the software from you, that

protection is automatically extended to everyone who receives the software,

no matter how they get it. 

Second, GPLv3~\S11\P7

prohibit anyone who made such an agreement from distributing software

released under GPLv3.    Conveyors are prohibited from

distributing software under GPLv3 if the conveyor makes an agreement of that

nature in the future.

The date in GPLv3~\S11\P7 likely seems arbitrary to those who did not follow

the GPLv3 drafting process.  This issue was hotly debated during the drafting of

GPLv3, but ultimately one specific deal of this type --- a deal between Microsoft

and Novell for Microsoft to provide so-called ``coupons'' to Microsoft customers to redeem

for copies of Novell's GNU/Linux distribution with a Microsoft patent license -- was

designed to be excluded.

The main reason for this was a tactical decision by the FSF.  FSF believed they can do more to

protect the community by allowing Novell to use software under GPLv3

than by forbidding it to do so.  This is because of

paragraph 6 of section 11 (corresponding to paragraph 4 in Draft 3).

It will apply, under the Microsoft/Novell deal, because of the coupons

that Microsoft has acquired that essentially commit it to participate

in the distribution of the Novell SLES GNU/Linux system.

The FSF also gave a secondary reason:  to avoid affecting other kinds of agreements for

other kinds of activities.  While GPLv3 sought to 

distinguish pernicious deals of the Microsoft/Novell type from

business conduct that is not particularly harmful, the FSF also did not

assume success in that drafting, and thus there remained some risk that other

unchangeable past agreements could fall within the  scope of GPLv3~\S11\P7.

In future deals, distributors engaging in ordinary business practices

can structure the agreements so that they do not fall under GPLv3~\S11\P7.

\section{GPLv3~\S12: Familiar as GPLv2~\S7}

GPLv2~\S12 remains almost completely unchanged from the text that appears

GPLv2~\S7.  This is an important provision that ensures a catch-all to ensure

that nothing ``surprising'' interferes with the continued conveyance safely

under copyleft.

The wording in the first sentence of GPLv3~\S12 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 the historical interpretation of GPLv2.

GPLv3 removed the limited severability clause of GPLv2~\S7 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. GPLv3 also removed

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

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

The Affero GPL was written with the expectation that its

additional requirement would be incorporated into the terms of GPLv3

itself.  Many software freedom advocates, including some authors of this

tutorial, advocated heavily for that, and fully expected it to happen.

The FSF, however, chose not to include the Affero clause in GPLv3, due to

what it called  ``irreconcilable views from

different parts of the community''.  Many

commercial users of Free Software were opposed to the inclusion of a

mandatory Affero-like requirement in the body of GPLv3 itself.  In fact, some

wealthier companies even threatened to permanently fund forks of many FSF

copyrighted-programs under GPLv2 if the Affero clause appeared in GPLv3.

Meanwhile, there was disagreement even among copyleft enthusiasts about the

importance of the provision.  A coalition never formed, and ultimately the

more powerful interest implicitly allied with the companies who deeply opposed

the Affero clause such that the FSF felt the Affero clause would need its own

license, but one compatible with GPLv3. 

GPLv3~\S13 makes GPLv3 compatible with the AGPLv3, so that at least code can

be shared between AGPLv3'd and GPLv3' projects, even if the Affero clause

does not automatically apply to all GPLv3'd works.

%FIXME-LATER:  no time to do this justice, will come back later, instead the

%above.

%% Some of this hostility seemed to be based on a misapprehension that

%% Affero-like terms placed on part of a covered work would somehow extend

%% to the whole of the work.\footnote{It is possible that the presence of

%% the GPLv2-derived copyleft clause in the existing Affero GPL contributed

%% to this misunderstanding.}  Our explanations to the contrary did little

%% to satisfy these critics; their objections to 7b4 instead evolved into a

%% broader indictment of the additional requirements scheme of section 7.

%% It was clear, however, that much of the concern about 7b4 stemmed from

%% its general formulation.  Many were alarmed at the prospect of GPLv3

%% compatibility for numerous Affero-like licensing conditions,

%% unpredictable in their details but potentially having significant

%% commercial consequences.

%% On the other hand, many developers, otherwise sympathetic to the policy