For example, some versions of Microsoft's FrontPage software prohibit use

\section{GPL \S 0: Freedom to Run}

In essence, the license governs \emph{only} those activities and all other

Thus, the GPL protects users fair and unregulated use rights precisely by

The bulk of \S 0 not yet discussed gives definitions for other terms used

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

because it clears up a common misconception about the GPL\@.

The GPL is often mistakenly criticized because it fails to give a

definition of ``derivative work''.  In fact, it would be incorrect and

problematic if the GPL attempt to define this.  A copyright license, in

fact, has no control over what may or may not be a derivative work.  This

matter is left up to copyright law, not the licenses that utilize it.

It is certainly true that copyright law as a whole does not propose clear

and straightforward guidelines for what is and is not a derivative

software work under copyright law.  However, no copyright license --- not

even the GNU GPL -- can be blamed for this.  Legislators and court

opinions must give us guidance to decide the border cases.

\section{GPL \S 1: Verbatim Copying}

GPL \S 1 covers the matter of redistributing the source code of a program

exactly as it was received.  This section is quite straightforward.

However, there are a few details worth noting here.

The phrase ``in any medium'' is important.  This, for example, gives the

freedom to publish a book that is the printed copy of the program's source

code.  It also allows for changes in the medium of distribution.  Some

vendors may ship Free Software on a CD, but others may place it right on

the hard drive of a pre-installed computer.  Any such redistribution media

is allowed.

Preservation of copyright notice and license notifications are mentioned

specifically in \S 1.  These are in some ways the most important part of

the redistribution, which is why they are mentioned by name.  The GPL

always strives to make it abundantly clear to anyone who receives the

software what its license is.  The goal is to leave no reason that someone

would be surprised that the software she got was licensed under GPL\@.

Thus throughout the GPL, there are specific reference to the importance of

notifying others down the distribution chain that they have rights under

GPL.

Also mentioned by name is the warranty disclaimer.  Most people today do

not believe that software comes with any warranty.  Notwithstanding the

proposed state-level UCITA bills (which have never obtained widespread

adoption), there are little or no implied warranties with software.

However, just to be on the safe side, GPL clearly disclaims them, and the

GPL requires redistributors to keep the disclaimer very visible.  (See

Sections~\ref{GPLs11} and~\ref{GPLs12} of this tutorial for more on GPL's

warranty disclaimers.)

Note finally that \S 1 begins to set forth the important defense of

commercial freedom.  \S 1 clearly states that in the case of verbatim

copies, one may make money.  Redistributors are fully permitted to charge

for the redistribution of copies of Free Software.  In addition, they may

provide the warranty protection that the GPL disclaims as an additional

service for a fee.  (See Section~\ref{Business Models} for more discussion

on making profit from Free Software redistribution.)

\section{GPL \S 2: Share and Share Alike}

Many consider \S 2 the heart and soul of the GPL\@.  For many, this is

where the ``magic'' happens that defends software freedom along the

distribution chain.  I certainly agree that if GPL has a soul, this is

where it is.  However, I argue that the heart is in fact contained in \SS

4--5 (see Section~\ref{GPLs4} and~\ref{GPLs5} of this tutorial).  But, for

the moment, let us consider the soul.

\S 2 gives the only permission in the GPL that governs the modification

controls of copyright law.  If someone modifies a GPL'ed program, she is

bound in the making those changes by \S 2.  The goal here is to ensure

that the body of GPL'ed software, as it continues and develops, remains

Free as in freedom.

To achieve that goal, \S 2 first sets forth that the rights of

redistribution modified versions are the same as those for verbatim

copying, as presented in \S 1.  Therefore, the details of charging,

keeping copyright notices in tact, and other \S 1 provisions are in tact

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

The first (\S 2(a)) requires that modified files carry ``prominent

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

The goal here is not to put forward some specific way of marking changes,

or controlling the process of how changes get made.  Primarily, \S 2(a)

seeks to ensure that those receiving modified versions what path it took

to them.  For some users, it is important to know that they are using the

canonical version of program, because while there are many advantages to

using a fork, there are a few disadvantages.  Users should be informed the

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

proper support choices.  Finally, \S 2(a) serves an academic purpose ---

ensuring that future developers can use a diachronic approach to

understand the software.

\medskip

The second requirement (\S 2(b)) contains the four short lines that embody

the legal details of ``share and share alike''.  These 46 words are

considered by some to be the most worthy of careful scrutiny.  It is worth

the effort to carefully understand what each clause is saying, because \S

2(b) can be a source of great confusion when not properly understood.

In considering \S 2(b), first note the qualifier: it only applies to

derivative works that ``you distribute or publish''.  Despite years of

education efforts by FSF on this matter, many still believe that modifiers

of GPL'ed software are required by the license to publish or otherwise

share their changes.  On the contrary, \S 2(b) {\bf does not apply if} the

changes are never distributed.  Indeed, the freedom to make private,

personal changes to software that are not shared should be protected and

defended\footnote{FSF does maintain that there is an {\bf ethical}

  obligation to redistributor changes that are generally useful, and often

  encourages companies and individuals to do so.  However, there is a

  clear distinction between what one {\bf ought} to do and what one {\bf

    must} do.}.

Next, we again encounter the same matter that appears in \S 0, in the

following text:

\begin{quote}

... that in whole or part contains or is derived from the Program or any

  part thereof,

\end{quote}

Again, the GPL relies here on what the copyright law says is a derivative

work.  If, under copyright law, the modified version ``contains or is

derived from'' the GPL'ed software, then the requirements of \S 2(b)

apply.  The GPL invokes its control as a copyright license over the

modification of the work in combination with its control over distribution

of the work.

The final clause of \S 2(b) describes what the licensee must do if she is

distributing or publishing a work that is deemed a derivative work under

copyright law --- namely, the following:

\begin{quote}

[The work must] be licensed as a whole at no charge to all third parties

under the terms of this License.

\end{quote}

That is probably the most tightly-packed phrase in all of the GPL\@.

Consider each subpart carefully.

The work ``as a whole'' is what is to be licensed.  This is an important

point that \S 2 spends an entire paragraph explaining; thus this phrase is

worthy of a lengthy discussion here.  As a programmer modifies a software

program, she generates new copyrighted material --- fixing ideas in the

tangible medium of electronic file storage.  That programmer is indeed the

copyright holder of those new changes.  However, those changes are part

and parcel to the original worked distributed to the programmer under

GPL\@.  Thus, the license of the original work affects the license of the

new whole derivative work.

% {\cal I}

\newcommand{\gplusi}{$\mathcal{G\!\!+\!\!I}$}

\newcommand{\worki}{$\mathcal{I}$}

\newcommand{\workg}{$\mathcal{G}$}

It is certainly possible to take an existing independent work (called

\worki{}) and combine it with a GPL'ed program (called \workg{}).  The

license of \worki{}, when it is distributed as a separate and independent

work, remains the prerogative of the copyright holder of .  However, when

\worki{} is combined with \workg{}, it produces a new work that is the

combination of the two (called \gplusi{}).  The copyright of this

derivative work, \gplusi{}, is jointly held by the original copyright

holder of each of the two works.

In this case, \S 2 lays out the terms by which \gplusi{} may be

distributed and copied.  By default, under copyright law, the copyright

holder of \worki{} would not have been permitted to distribute \gplusi{};

copyright law forbids it without the expressed permission of the copyright

holder of \workg{}.  (Imagine, for a moment, if \workg{} were a Microsoft

product --- would they give you permission to create and distribute

\gplusi{} without paying them a hefty sum?)  The license of \workg{}, the

GPL, sets forth ahead of time options for the copyright holder of \worki{}

who may want to create and distribute \gplusi{}.  This pre-granted

permission to create and distribute derivative works, provided the terms

of GPL are uphold, goes far above and beyond the permissions that one

would get with a typical work not covered by a copyleft license.  Thus, to

say that this restriction is any way unreasonable is simply ludicrous.

\medskip

The next phrase of note in \S 2(b) is ``licensed ... at no charge''.  This

is a source of great confusion to many.  Not a month goes by that FSF does

not receive an email that claims to point out ``a contradiction in GPL''

because \S 2 says that redistributors cannot charge for modified versions

of GPL'ed software, but \S 1 says that they can.  The ``at no charge''

means not that redistributors cannot charge for performing the acts

governed by copyright law\footnote{Recall that you could by default charge

  for any acts not governed by copyright law, because the license controls

  are confined by copyright.}, but rather that they cannot charge a fee

for the \emph{license itself}.  In other words, redistributors of

(modified and unmodified) GPL'ed works may charge any amount they choose

for performing the modifications on contract or the act of transferring

the copy to the customer, but they may not charge a separate licensing fee

for the software.

\S 2(b) further states that the software must ``be licensed ... to all

third parties''.  This too has led to some confusions, and feeds the

misconception mentioned earlier --- that all modified versions must made

available to the public at large.  However, the text here does not say

that.  Instead, it says that the licensing under terms of the GPL must

extend to anyone who might, through the typical distribution chain,

receive a copy of the software.  Distribution to all third parties is not

mandated here, but \S 2(b) does require redistributors to license the

derivative works in a way that is extends FIXME to all third parties who may

ultimately receive a copy of the software.

In summary, \S 2(b) says what terms under which the third parties must

receive this no-charge license.  Namely, they receive it ``under the terms

of this License'', the GPL.  When an entity \emph{chooses} to redistribute

a derivative work of GPL'ed software, the license of that whole derivative

work must be GPL and only GPL\@.  In this manner, \S 2(b) dovetails nicely

with \S 6 (as discussed in Section\~ref{GPLs6} of this tutorial).

\medskip

The final paragraph of \S 2 is worth special mention.  It is possible and

quite common to aggregate various software programs together on one

distribution medium.  Computer manufacturers do this when they ship a

pre-installed hard drive, and GNU/Linux distribution vendors do this to

give a one-stop CD or URL for a complete operating system with necessary

applications.  The GPL very clearly permits such ``mere aggregation'' with

programs under any license.  Despite what you hear from its critics, the

GPL is nothing like a virus, not only because the GPL is good for you and

a virus is bad for you, but also because simple contact with a GPL'ed

code-base does not impact the license of other programs.  Actual effort

must be expended by a programmer to cause a work to fall under the terms

of the GPL.  Redistributors are always welcome to simply ship GPL'ed

software alongside proprietary software or other unrelated Free Software,

as long as the terms of GPL are adhered to for those packages that are

truly GPL'ed.

\label{GPLs4}

\section{GPL, \S 8}

\label{GPLs8}

\section{GPL, \S 9}

\label{GPLs9}

\section{GPL, \S 10}

\label{GPLs10}

\section{GPL, \S 11}

\label{GPLs11}

to make such language "conspicuous" people started placing it in bold or caps it.  My question

\section{GPL, \S 12}

\label{GPLs12}

\chapter{Integrating the GPL into Business Practices}

\section{Using Free Software In-House}

\section{Business Models}

\label{Business Models}

\section{Ongoing Compliance}

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% LocalWords:  Yoyodyne FrontPage improvers Berne copyrightable Stallman's GPLs

% LocalWords:  Lessig Lessig's UCITA pre