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%      Tutorial Text for the Detailed Study and Analysis of GPL and LGPL course

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% Copyright (C) 2014                   Bradley M. Kuhn

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\newcommand{\defn}[1]{\emph{#1}}

\part{Detailed Analysis of the GNU GPL and Related Licenses}

\begin{center}

{\parindent 0in

\tutorialpartsplit{``Detailed Analysis of the GNU GPL and Related Licenses''}{This part} is: \\

\begin{tabbing}

Copyright \= \copyright{} 2003, 2004, 2005, 2006 \= \hspace{.2in} Free Software Foundation, Inc. \\

Copyright \= \copyright{} 2014 \= \hspace{.2in} Bradley M. Kuhn \\

Copyright \= \copyright{} 2014 \= \hspace{.2in} Anthony K. Sebro, Jr. \\

\end{tabbing}

Authors of \tutorialpartsplit{``Detailed Analysis of the GNU GPL and Related Licenses''}{this part} are: \\

Free Software Foundation, Inc. \\

Bradley M. Kuhn \\

David ``Novalis'' Turner \\

Daniel B. Ravicher \\

Tony Sebro \\

John Sullivan

\vspace{.3in}

The copyright holders of \tutorialpartsplit{``Detailed Analysis of the GNU GPL and Related Licenses''}{this part} hereby grant the freedom to copy, modify,

convey, Adapt, and/or redistribute this work under the terms of the Creative

Commons Attribution Share Alike 4.0 International License.  A copy of that

license is available at

\verb=https://creativecommons.org/licenses/by-sa/4.0/legalcode=.  }

\end{center}

\bigskip

\bigskip

\tutorialpartsplit{This tutorial}{This part of the tutorial} gives a

comprehensive explanation of the most popular Free Software copyright

license, the GNU General Public License (``GNU GPL'', or sometimes just

``GPL'') -- both version 2 (``GPLv2'') and version 3 (``GPLv3'') -- and

teaches lawyers, software developers, managers and business people how to use

the GPL (and GPL'd software) successfully both as a community-building

software into a new Free Software business and in existing, successful

enterprises.

To successfully benefit of from this part of the tutorial, readers should

understanding of how copyright law applies to software is also helpful.  The

tutorial is of most interest to lawyers, software developers and managers who

run or advise software businesses that modify and/or redistribute software

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

to have learned the following:

\begin{itemize}

  \item The differences between GPLv2 and GPLv3.

  \item The redistribution options under the GPLv2 and GPLv3.

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

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

  \item The business advantages that the GPL provides.

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

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

    differs from the GPLv2 and GPLv3, respectively.

  \item The basics to begin understanding the complexities regarding

    derivative and combined works of software.

\end{itemize}

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% END OF ABSTRACTS SECTION

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% START OF DAY ONE COURSE

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\chapter{What Is Software Freedom?}

Study of the GNU General Public License (herein, abbreviated as \defn{GNU

  GPL} or just \defn{GPL}) must begin by first considering the broader world

of software freedom. The GPL was not created from a void, rather, it was

created to embody and defend a set of principles that were set forth at the

founding of the GNU project and the Free Software Foundation (FSF) -- the

organization that upholds, defends and promotes the philosophy of software

freedom. A prerequisite for understanding both of the popular versions of GPL

(GPLv2 and GPLv3) and their terms and conditions is a basic understanding of

the principles behind it.  The GPL family of licenses are unlike almost all

other software licenses in that they are designed to defend and uphold these

principles.

\section{The Free Software Definition}

\label{Free Software Definition}

The Free Software Definition is set forth in full on FSF's website at

\verb0http://fsf.org/0 \verb0philosophy/free-sw.html0. This section presents

an abbreviated version that will focus on the parts that are most pertinent

to the GPL\@.

A particular program grants software freedom to a particular user if that

user is granted the following freedoms:

\begin{itemize}

\item The freedom to run the program, for any purpose.

\item The freedom to study how the program works, and modify it

\item The freedom to redistribute copies.

\item The freedom to distribute copies of  modified versions to others.

\end{itemize}

The focus on ``a particular user'' is particularly pertinent here.  It is not

uncommon for the same version of a specific program to grant these freedoms

to some subset of its user base, while others have none or only some of these

freedoms.  Section~\ref{Proprietary Relicensing} talks in detail about how

this can unfortunately happen even if a program is released under the GPL\@.

Many people refer to software that gives these freedoms as ``Open Source.''

Besides having a different political focus than those who call it Free

Software,\footnote{The political differences between the Free Software

  Movement and the Open Source Movement are documented on FSF's Web site at

  {\tt http://www.fsf.org/licensing/essays/free-software-for-freedom.html}.}

those who call the software ``Open Source'' are often focused on a side

issue.  Specifically, user access to the source code of a program is a

prerequisite to make use of the freedom to modify.  However, the important

issue is what freedoms are granted in the license of that source code.

Software freedom is only complete when no restrictions are imposed on how

these freedoms are exercised.  Specifically, users and programmers can

exercise these freedoms noncommercially or commercially.  Licenses that grant

these freedoms for noncommercial activities but prohibit them for commercial

activities are considered non-free.  Even the Open Source Initiative

(\defn{OSI}) (the arbiter of what is considered ``Open Source'') also rules

such licenses not in fitting with their ``Open Source Definition''.

In general, software for which most or all of these freedoms are

restricted in any way is called ``non-Free Software.''  Typically, the

term ``proprietary software'' is used more or less interchangeably with

``non-Free Software.''  Personally, I tend to use the term ``non-Free

Software'' to refer to noncommercial software that restricts freedom

(such as ``shareware'') and ``proprietary software'' to refer to

commercial software that restricts freedom (such as nearly all of

Microsoft's and Oracle's offerings).

Keep in mind that the none of the terms ``software freedom'', ``open source''

and ``free software'' are not known to be trademarked by any organization in

any jurisdiction.  As such, it's quite common that these terms are abused and

misused by parties who wish to bank on the popularity of software freedom.

When one considers using, modifying or redistributing a software package that

purports to be Open Source or Free Software, one \textbf{must} verify that

the license grants software freedom

Furthermore, throughout this text, we generally prefer the term ``software

freedom'', as this is the least ambiguous term available to describe software

that meets the Free Software Definition.  For example, it is well known and

often discussed that the adjective ``free'' has two unrelated meanings in

English: ``free as in freedom'' and ``free as in price''.  Meanwhile, the

term ``open source'' is even more confusing, because it refers only to the

``freedom to study'', which is merely a subset of one of the four freedoms.

The remainder of this section considers each of each component of software

freedom in detail.

\subsection{The Freedom to Run}

The first tenant of software freedom is the user's fully unfettered right to

run the program.  The software's license must permit any conceivable use of

the software.  Perhaps, for example, the user has discovered an innovative

use for a particular program, one that the programmer never could have

predicted.  Such a use must not be restricted.

It was once rare that this freedom was restricted by even proprietary

software; but such is quite common today. Most End User Licensing Agreements

(EULAs) that cover most proprietary software typically restrict some types of

uses.  Such restrictions of any kind are an unacceptable restriction on

software freedom.

\subsection{The Freedom to Change and Modify}

Perhaps the most useful right of software freedom is the users' right to

change, modify and adapt the software to suit their needs.  Access to the

source code and related build and installation scripts are an essential part

of this freedom.  Without the source code, and the ability to build and

install the binary applications from that source, users cannot effectively

exercise this freedom.

Programmers take direct benefit from this freedom.  However, this freedom

remains important to users who are not programmers.  While it may seem

counterintuitive at first, non-programmer users often exercise this freedom

indirectly in both commercial and noncommercial settings.  For example, users

often seek noncommercial help with the software on email lists and in users

groups.  To make use of such help they must either have the freedom to

recruit programmers who might altruistically assist them to modify their

software, or to at least follow rote instructions to make basic modifications

themselves.

More commonly, users also exercise this freedom commercially.  Each user, or

group of users, may hire anyone they wish in a competitive free market to

modify and change the software.  This means that companies have a right to

hire anyone they wish to modify their Free Software.  Additionally, such

companies may contract with other companies to commission software

modification.

\subsection{The Freedom to Copy and Share}

Users share Free Software in a variety of ways. Software freedom advocates

work to eliminate a fundamental ethical dilemma of the software age: choosing

between obeying a software license and friendship (by giving away a copy of a

program to your friend who likes the software you are using). Licenses that

respect software freedom, therefore, permit altruistic sharing of software

among friends.

The commercial environment also benefits of this freedom.  Commercial sharing

includes selling copies of Free Software: Free Software can be sold at any

price to anyone.  Those who redistribute Free Software commercially also have

the freedom to selectively distribute (i.e., you can pick your customers) and

to set prices at any level that redistributor sees fit.

Of course, most people get copies of Free Software very cheaply (and

sometimes without charge).  The competitive free market of Free Software

tends to keep prices low and reasonable.  However, if someone is willing to

pay billions of dollars for one copy of the GNU Compiler Collection, such a

sale is completely permitted.

Another common instance of commercial sharing is service-oriented

distribution.  For example, some distribution vendors provide immediate

security and upgrade distribution via a special network service.  Such

distribution is not necessarily contradictory with software freedom.

(Section~\ref{Business Models} of this tutorial talks in detail about some

common Free Software business models that take advantage of the freedom to

share commercially.)

\subsection{The Freedom to Share Improvements}

The freedom to modify and improve is somewhat empty without the freedom to

share those improvements.  The Software freedom community is built on the

pillar of altruistic sharing of improved Free Software. Inevitably, a

Free Software project sprouts a mailing list where improvements are shared

freely among members of the development community.  Such noncommercial

sharing is the primary reason that Free Software thrives.

Commercial sharing of modified Free Software is equally important.

For commercial support to exist in a competitive free market, all

developers -- from single-person contractors to large software

companies -- must have the freedom to market their services as

improvers of Free Software.  All forms of such service marketing must

be equally available to all.

For example, selling support services for Free Software is fully

permitted. Companies and individuals can offer themselves as ``the place

to call'' when software fails or does not function properly.  For such a

service to be meaningful, the entity offering that service needs the