protection given to the expression containing them.

\subsection{Comparison}

The third and final step of the AFC test entails a comparison of the

original program's remaining protectable expression to a second

program. The issue will be whether any of the protected expression is

copied in the second program and, if so, what relative importance the

copied portion has with respect to the original program overall. The

ultimate inquiry is whether there is ``substantial'' similarity between

the protected elements of the original program and the potentially

derivative work. The courts admit that this process is primarily

qualitative rather than quantitative and is performed on a case-by-case

basis. In essence, the comparison is an ad hoc determination of whether

the protectable elements of the original program that are contained in the

second work are significant or important parts of the original program. If

so, then the second work is a derivative work of the first. If, however,

the amount of protectable elements copied in the second work are so small

as to be de minimis, then the second work is not a derivative work of the

original.

\section{Analytic Dissection Test}

The Ninth Circuit has adopted the analytic dissection test to determine

whether one program is a derivative work of another. Apple Computer,

Inc. v. Microsoft Corp., 35 F.3d 1435 (9th Cir. 1994). The analytic

dissection test first considers whether there are substantial similarities

in both the ideas and expressions of the two works at issue. Once the

similar features are identified, analytic dissection is used to determine

whether any of those similar features are protected by copyright. This

step is the same as the filtration step in the AFC test. After identifying

the copyrightable similar features of the works, the court then decides

whether those features are entitled to ``broad'' or ``thin''

protection. ``Thin'' protection is given to non-copyrightable facts or

ideas that are combined in a way that affords copyright protection only

from their alignment and presentation, while ``broad'' protection is given

to copyrightable expression itself. Depending on the degree of protection

afforded, the court then sets the appropriate standard for a subjective

comparison of the works to determine whether, as a whole, they are

sufficiently similar to support a finding that one is a derivative work of

the other. ``Thin'' protection requires the second work be virtually

identical in order to be held a derivative work of an original, while

``broad'' protection requires only a ``substantial similarity.''

\section{No Protection for ``Methods of Operation''}

The First Circuit has taken the position that the AFC test is inapplicable 

when the works in question relate to unprotectable elements set forth in 

of derivative work for software in comparison to other circuits. Specifically, 

the

the Copyright Act, refers to the means by which users operate

computers. Lotus Development Corp. v. Borland Int’l., Inc., 49 F.3d 807

(1st Cir. 1995).  In Lotus, the court held that a menu command

hierarchy for a computer program was uncopyrightable because it did not

merely explain and present the program’s functional capabilities to the

user, but also served as a method by which the program was operated and

controlled. As a result, under the First Circuit’s test, literal copying

of a menu command hierarchy, or any other ``method of operation,'' cannot

form the basis for a determination that one work is a derivative of

another.  As a result, courts in the First Circuit that apply the AFC test

unprotected elements. E.g., Real View, LLC v. 20-20 Technologies, Inc., 

683 F. Supp.2d 147, 154 (D. Mass. 2010).

\section{No Test Yet Adopted}

Several circuits, most notably the Fourth and Seventh, have yet to

declare their definition of derivative work and whether or not the

AFC, Analytic Dissection, or some other test best fits their

interpretation of copyright law. Therefore, uncertainty exists with

respect to determining the extent to which a software program is a

derivative work of another in those circuits. However, one may presume

that they would give deference to the AFC test since it is by far the

majority rule amongst those circuits that have a standard for defining

a software derivative work.

\section{Cases Applying Software Derivative Work Analysis}

In the preeminent case regarding the definition of a derivative work for

software, Computer Associates v. Altai, the plaintiff alleged that its

program, Adapter, which was used to handle the differences in operating

system calls and services, was infringed by the defendant's competitive

program, Oscar. About 30\% of Oscar was literally the same code as

that in Adapter. After the suit began, the defendant rewrote those

portions of Oscar that contained Adapter code in order to produce a new

version of Oscar that was functionally competitive with Adapter, without

have any literal copies of its code. Feeling slighted still, the

plaintiff alleged that even the second version of Oscar, despite having no

literally copied code, also infringed its copyrights. In addressing that

question, the Second Circuit promulgated the AFC test.

In abstracting the various levels of the program, the court noted a

similarity between the two programs' parameter lists and macros. However,

following the filtration step of the AFC test, only a handful of the lists

and macros were protectable under copyright law because they were either

in the public domain or required by functional demands on the

program. With respect to the handful of parameter lists and macros that

did qualify for copyright protection, after performing the comparison step

of the AFC test, it was reasonable for the district court to conclude that

they did not warrant a finding of infringement given their relatively minor

contribution to the program as a whole. Likewise, the similarity between

the organizational charts of the two programs was not substantial enough

to support a finding of infringement because they were too simple and

obvious to contain any original expression.

In the case of Oracle America v. Google, 872 F. Supp.2d 974 (N.D. Cal. 2012),

the Northern District of California District Court examined the question of 

whether the application program interfaces (APIs) associated with the Java

programming language are entitled to copyright protection.  While the 

court expressly declined to rule whether all APIs are free to use without 

license (872 F. Supp.2d 974 at 1002), the court held that the command 

structure and taxonomy of the APIs were not protectable under copyright law.

Specifically, the court characterized the command structure and taxonomy as

both a ``method of operation'' (using an approach not dissimilar to the 

First Circuit's analysis in Lotus) and a ``functional requirement for 

compatability'' (using Sega v. Accolade, 977 F.2d 1510 (9th Cir. 1992) and

Sony Computer Ent. v. Connectix, 203 F.3d 596 (9th Cir. 2000) as analogies),

Perhaps not surprisingly, there have been few other cases involving a highly

detailed software derivative work analysis. Most often, cases involve

clearer basis for decision, including frequent bad faith on the part of

the defendant or overaggressiveness on the part of the plaintiff.  

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

\chapter{Modified Source and Binary Distribution}

\label{source-and-binary}

In this chapter, we discuss the two core sections that define the rights

and obligations for those who modify, improve, and/or redistribute GPL'd

software. These sections, GPLv2~\S\S2--3, define the central core rights and

requirements of GPLv2\@.

\section{GPLv2~\S2: Share and Share Alike}

For many, this is where the ``magic'' happens that defends software

freedom upon redistribution.  GPLv2~\S2 is the only place in GPLv2

that governs the modification controls of copyright law.  If users

modifies a GPLv2'd program, they must follow the terms of GPLv2~\S2 in making

those changes.  Thus, this sections ensures that the body of GPL'd software, as it

continues and develops, remains Free as in freedom.

To achieve that goal, GPLv2~\S2 first sets forth that the rights of

redistribution of modified versions are the same as those for verbatim

copying, as presented in GPLv2~\S1.  Therefore, the details of charging money,

keeping copyright notices intact, and other GPLv2~\S1 provisions are in tact

here as well.  However, there are three additional requirements.

The first (GPLv2~\S2(a)) requires that modified files carry ``prominent

notices'' explaining what changes were made and the date of such

changes. This section does not prescribe some specific way of

marking changes nor does it control the process of how changes are made.

Primarily, GPLv2~\S2(a) seeks to ensure that those receiving modified

versions know the history of changes to the software.  For some users,

it is important to know that they are using the standard version of

program, because while there are many advantages to using a fork,

there are a few disadvantages.  Users should be informed about the

historical context of the software version they use, so that they can

make proper support choices.  Finally, GPLv2~\S2(a) serves an academic

purpose --- ensuring that future developers can use a diachronic

approach to understand the software.

\medskip

The second requirement (GPLv2~\S2(b)) contains the four short lines that embody

\newcommand{\compA}{$\mathcal{A}$}

For example, if Company \compA{} has a patent on advanced Web browsing, but

also licenses a Web browsing software program under the GPLv2, then it

cannot assert the patent against any party based on that party's use of 

Company \compA{}'s GPL'ed Web browsing software program, or on that party's

creation and use of derivative works of that GPL'ed program.  However, if a

party uses that program without

complying with the GPLv2, then Company \compA{} can assert both copyright

infringement claims against the non-GPLv2-compliant party and

infringement of the patent, because the implied patent license only

extends to use of the software in accordance with the GPLv2. Further, if

Company \compB{} distributes a competitive advanced Web browsing program 

that is not a derivative work of Company \compA{}'s GPL'ed Web browsing software

program, Company \compA{} is free to assert its patent against any user or

distributor of that product. It is irrelevant whether Company \compB's

program is also distributed under the GPLv2, as Company \compB{} can not grant

implied licenses to Company \compA's patent.

This result also reassures companies that they need not fear losing their

proprietary value in patents to competitors through the GPLv2 implied patent

license, as only those competitors who adopt and comply with the GPLv2's

terms can benefit from the implied patent license. To continue the

example above, Company \compB{} does not receive a free ride on Company

\compA's patent, as Company \compB{} has not licensed-in and then

redistributed Company A's advanced Web browser under the GPLv2. If Company

\compB{} does do that, however, Company \compA{} still has not lost

competitive advantage against Company \compB{}, as Company \compB{} must then,

when it re-distributes Company \compA's program, grant an implied license

to any of its patents that cover the program. Further, if Company \compB{}

relicenses an improved version of Company A's program, it must do so under

the GPLv2, meaning that any patents it holds that cover the improved version

are impliedly licensed to any licensee. As such, the only way Company

\compB{} can benefit from Company \compA's implied patent license, is if it,

itself, distributes Company \compA's software program and grants an

implied patent license to any of its patents that cover that program.

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

\chapter{Defending Freedom on Many Fronts}

Chapters~\ref{run-and-verbatim} and~\ref{source-and-binary} presented the

core freedom-defending provisions of GPLv2\@, which are in GPLv2~\S\S0--3.

GPLv2\S\S~4--7 of the GPLv2 are designed to ensure that GPLv2~\S\S0--3 are

not infringed, are enforceable, are kept to the confines of copyright law but

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

\section{GPLv2~\S4: Termination on Violation}

\label{GPLv2s4}

GPLv2~\S4 is GPLv2's termination clause.  Upon first examination, it seems

strange that a license with the goal of defending users' and programmers'

freedoms for perpetuity in an irrevocable way would have such a clause.

However, upon further examination, the difference between irrevocability

and this termination clause becomes clear.

The GPL is irrevocable in the sense that once a copyright holder grants

rights for someone to copy, modify and redistribute the software under terms

of the GPL, they cannot later revoke that grant.  Since the GPL has no

provision allowing the copyright holder to take such a prerogative, the

license is granted as long as the copyright remains in effect.\footnote{In

  the USA, due to unfortunate legislation, the length of copyright is nearly

  perpetual, even though the Constitution forbids perpetual copyright.} The

copyright holders have the right to relicense the same work under different

licenses (see Section~\ref{Proprietary Relicensing} of this tutorial), or to

stop distributing the GPLv2'd version (assuming GPLv2~\S3(b) was never used),

but they may not revoke the rights under GPLv2 already granted.

In fact, when an entity looses their right to copy, modify and distribute

GPL'd software, it is because of their \emph{own actions}, not that of the

copyright holder.  The copyright holder does not decided when GPLv2~\S4

termination occurs (if ever); rather, the actions of the licensee determine

that.

Under copyright law, the GPL has granted various rights and freedoms to

the licensee to perform specific types of copying, modification, and

redistribution.  By default, all other types of copying, modification, and

redistribution are prohibited.  GPLv2~\S4 says that if you undertake any of

those other types (e.g., redistributing binary-only in violation of GPLv2~\S3),

then all rights under the license --- even those otherwise permitted for

those who have not violated --- terminate automatically.

GPLv2~\S4 makes GPLv2 enforceable.  If licensees fail to adhere to the

license, then they are stuck without any permission under to engage in

activities covered by copyright law.  They must completely cease and desist

from all copying, modification and distribution of the GPL'd software.

At that point, violating licensees must gain the forgiveness of the copyright

holders to have their rights restored.  Alternatively, the violators could

negotiate another agreement, separate from GPL, with the copyright

holder.  Both are common practice, although

\tutorialpartsplit{as discussed in \textit{A Practical Guide to GPL

    Compliance}, there are }{Chapter~\ref{compliance-understanding-whos-enforcing}

  explains further } key differences between these two very different uses of GPL.

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.

% 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

% FIXME: Section header needed here about choice of law.

% FIXME: reword into tutorial

Some have asked us to address the difficulties of internationalization

by including, or permitting the inclusion of, a choice of law

provision.  We maintain that this is the wrong approach.  Free

software licenses should not contain choice of law clauses, for both

legal and pragmatic reasons.  Choice of law clauses are creatures of

contract, but the substantive rights granted by the GPL are defined

from the LGPL'd software.

For efficiency, when a compiler turns source code into object code, it

sometimes places literal portions of the copyrighted library code into the

object code for an otherwise separate independent work. In the normal

scenario, the derivative would not be created until final assembly and

linking of the executable occurred. However, when the compiler does this

efficiency optimization, at the intermediate object code step, a

derivative work is created.

LGPLv2.1~\S5\P4 is designed to handle this specific case. The intent of

the license is clearly that simply compiling software to ``make use'' of

the library does not in itself cause the compiled work to be a ``work

based on the library.''  However, since the compiler copies verbatim,

copyrighted portions of the library into the object code for the otherwise

separate and independent work, it would actually cause that object file to be a

``work based on the library.''  It is not FSF's intent that a mere

compilation idiosyncrasy would change the requirements on the users of the

LGPLv2.1'd software. This paragraph removes that restriction, allowing the

implications of the license to be the same regardless of the specific

mechanisms the compiler uses underneath to create the ``work that uses the

library.''

As it turns out, we have only once had anyone worry about this specific

idiosyncrasy, because that particular vendor wanted to ship object code

(rather than final binaries) to their customers and was worried about

this edge condition. The intent of clarifying this edge condition is

primarily to quell the worries of software engineers who understand the

level of verbatim code copying that a compiler often does, and to help

them understand that the full implications of LGPLv2.1 are the same regardless

of the details of the compilation progress.

\section{LGPLv2.1~\S6 \& LGPLv2.1~\S5: Combining the Works}

\label{lgpl-section-6}

Now that we have established a good working definition of works that

``use'' and works that ``are based on'' the library, we will consider the

rules for distributing these two different works.

The rules for distributing ``works that use the library'' are covered in

LGPLv2.1~\S6\@. LGPLv2.1~\S6 is much like GPLv2~\S3, as it requires the release

of source when a binary version of the LGPL'd software is released. Of

course, it only requires that source code for the library itself be made

available. The work that ``uses'' the library need not be provided in

source form. However, there are also conditions in LGPLv2.1~\S6 to make sure

that a user who wishes to modify or update the library can do so.

LGPLv2.1~\S6 lists five choices with regard to supplying library source

and granting the freedom to modify that library source to users. We

most common way currently used for LGPLv2.1 compliance on a ``work that

uses the library.''

LGPLv2.1~\S6(b) allows the distributor of a ``work that uses the library'' to

simply use a dynamically linked, shared library mechanism to link with the

library. This is by far the easiest and most straightforward option for

distribution. In this case, the executable of the work that uses the

library will contain only the ``stub code'' that is put in place by the

shared library mechanism, and at runtime the executable will combine with

the shared version of the library already resident on the user's computer.

If such a mechanism is used, it must allow the user to upgrade and

replace the library with interface-compatible versions and still be able

to use the ``work that uses the library.''  However, all modern shared

library mechanisms function as such, and thus LGPLv2.1~\S6(b) is the simplest

option, since it does not even require that the distributor of the ``work

2based on the library'' ship copies of the library itself.

LGPLv2.1~\S6(a) is the option to use when, for some reason, a shared library

mechanism cannot be used. It requires that the source for the library be

included, in the typical GPL fashion, but it also has a requirement beyond

that. The user must be able to exercise her freedom to modify the library

to its fullest extent, and that means recombining it with the ``work based

on the library.''  If the full binary is linked without a shared library

mechanism, the user must have available the object code for the ``work

based on the library,'' so that the user can relink the application and

build a new binary.

The remaining options in LGPLv2.1~\S6 are very similar to the other choices

provided by GPLv2~\S3. There are some additional options, but time does

not permit us in this course to go into those additional options. In

almost all cases of distribution under LGPL, either LGPLv2.1~\S6(a) or LGPLv2.1~\S6(b) are

exercised.

\section{Distribution of the Combined Works}

Essentially, ``works based on the library'' must be distributed under the

same conditions as works under full GPL\@. In fact, we note that 

LGPLv2.1~\S2 is nearly identical in its terms and requirements to GPLv2~\S2.

There are again subtle differences and additions, which time does not

permit us to cover in this course.

\section{And the Rest}

The remaining variations between LGPL and GPL cover the following

conditions:

\begin{itemize}