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@ -1070,9 +1070,9 @@ GPL requires redistributors to keep the disclaimer very visible. (See
Sections~\ref{GPLv2s11} and~\ref{GPLv2s12} of this tutorial for more on GPL's Sections~\ref{GPLv2s11} and~\ref{GPLv2s12} of this tutorial for more on GPL's
warranty disclaimers.) warranty disclaimers.)
Note finally that GPLv2~\S1 begins to set forth the important defense of Note finally that GPLv2~\S1 creates groundwork for the important defense of
commercial freedom. GPLv2~\S1 clearly states that in the case of verbatim commercial freedom. GPLv2~\S1 clearly states that in the case of verbatim
copies, one may make money. Redistributors are fully permitted to charge copies, one may make money. Redistributors are fully permitted to charge
for the redistribution of copies of Free Software. In addition, they may for the redistribution of copies of Free Software. In addition, they may
provide the warranty protection that the GPL disclaims as an additional provide the warranty protection that the GPL disclaims as an additional
service for a fee. (See Section~\ref{Business Models} for more discussion service for a fee. (See Section~\ref{Business Models} for more discussion
@ -1417,49 +1417,50 @@ requirements of GPLv2\@.
\section{GPLv2~\S2: Share and Share Alike} \section{GPLv2~\S2: Share and Share Alike}
For many, this is where the ``magic'' happens that defends software For many, this is where the ``magic'' happens that defends software
freedom along the distribution chain. GPLv2~\S2 is the only place in the GPL freedom upon redistribution. GPLv2~\S2 is the only place in GPLv2
that governs the modification controls of copyright law. If someone that governs the modification controls of copyright law. If users
modifies a GPL'd program, she is bound in the making those changes by modifies a GPLv2'd program, they must follow the terms of GPLv2~\S2 in making
GPLv2~\S2. The goal here is to ensure that the body of GPL'd software, as it those changes. Thus, this sections ensures that the body of GPL'd software, as it
continues and develops, remains Free as in freedom. continues and develops, remains Free as in freedom.
To achieve that goal, GPLv2~\S2 first sets forth that the rights of To achieve that goal, GPLv2~\S2 first sets forth that the rights of
redistribution of modified versions are the same as those for verbatim redistribution of modified versions are the same as those for verbatim
copying, as presented in GPLv2~\S1. Therefore, the details of charging, copying, as presented in GPLv2~\S1. Therefore, the details of charging money,
keeping copyright notices intact, and other GPLv2~\S1 provisions are in tact keeping copyright notices intact, and other GPLv2~\S1 provisions are in tact
here as well. However, there are three additional requirements. here as well. However, there are three additional requirements.
The first (GPLv2~\S2(a)) requires that modified files carry ``prominent The first (GPLv2~\S2(a)) requires that modified files carry ``prominent
notices'' explaining what changes were made and the date of such notices'' explaining what changes were made and the date of such
changes. The goal here is not to put forward some specific way of changes. This section does not prescribe some specific way of
marking changes nor controlling the process of how changes get made. marking changes nor does it control the process of how changes are made.
Primarily, GPLv2~\S2(a) seeks to ensure that those receiving modified Primarily, GPLv2~\S2(a) seeks to ensure that those receiving modified
versions know the history of changes to the software. For some users, 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 it is important to know that they are using the standard version of
program, because while there are many advantages to using a fork, program, because while there are many advantages to using a fork,
there are a few disadvantages. Users should be informed about the there are a few disadvantages. Users should be informed about the
historical context of the software version they use, so that they can historical context of the software version they use, so that they can
make proper support choices. Finally, GPLv2~\S2(a) serves an academic make proper support choices. Finally, GPLv2~\S2(a) serves an academic
purpose --- ensuring that future developers can use a diachronic purpose --- ensuring that future developers can use a diachronic
approach to understand the software. approach to understand the software.
\medskip \medskip
The second requirement (GPLv2~\S2(b)) contains the four short lines that embody The second requirement (GPLv2~\S2(b)) contains the four short lines that embody
the legal details of ``share and share alike.'' These 46 words are the legal details of ``share and share alike''. These 46 words are
considered by some to be the most worthy of careful scrutiny because GPLv2~\S2(b) considered by some to be the most worthy of careful scrutiny because
GPLv2~\S2(b), and they
can be a source of great confusion when not properly understood. can be a source of great confusion when not properly understood.
In considering GPLv2~\S2(b), first note the qualifier: it only applies to In considering GPLv2~\S2(b), first note the qualifier: it \textit{only} applies to
derivative works that ``you distribute or publish.'' Despite years of derivative works that ``you distribute or publish''. Despite years of
education efforts by FSF on this matter, many still believe that modifiers education efforts on this matter, many still believe that modifiers
of GPL'd software are required by the license to publish or otherwise of GPL'd software \textit{must} to publish or otherwise
share their changes. On the contrary, GPLv2~\S2(b) {\bf does not apply if} the share their changes. On the contrary, GPLv2~\S2(b) {\bf does not apply if} the
changes are never distributed. Indeed, the freedom to make private, changes are never distributed. Indeed, the freedom to make private,
personal, unshared changes to software for personal use only should be personal, unshared changes to software for personal use only should be
protected and defended.\footnote{FSF does maintain that there is an {\bf protected and defended.\footnote{Most Free Software enthusiasts believe there is an {\bf
ethical} obligation to redistribute changes that are generally useful, moral} obligation to redistribute changes that are generally useful,
and often encourages companies and individuals to do so. However, there and they often encourage companies and individuals to do so. However, there
is a clear distinction between what one {\bf ought} to do and what one is a clear distinction between what one {\bf ought} to do and what one
{\bf must} do.} {\bf must} do.}
@ -1469,9 +1470,9 @@ following text:
``...that in whole or part contains or is derived from the Program or any part thereof.'' ``...that in whole or part contains or is derived from the Program or any part thereof.''
\end{quote} \end{quote}
Again, the GPL relies here on what the copyright law says is a derivative 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 work. If, under copyright law, the modified version ``contains or is
derived from'' the GPL'd software, then the requirements of GPLv2~\S2(b) derived from'' the GPL'd software, then the requirements of GPLv2~\S2(b)
apply. The GPL invokes its control as a copyright license over the apply. The GPL invokes its control as a copyright license over the
modification of the work in combination with its control over distribution modification of the work in combination with its control over distribution
of the work. of the work.
@ -1487,10 +1488,10 @@ Consider each subpart carefully.
The work ``as a whole'' is what is to be licensed. This is an important The work ``as a whole'' is what is to be licensed. This is an important
point that GPLv2~\S2 spends an entire paragraph explaining; thus this phrase is point that GPLv2~\S2 spends an entire paragraph explaining; thus this phrase is
worthy of a lengthy discussion here. As a programmer modifies a software worthy of a lengthy discussion here. As a programmer modifies a software
program, she generates new copyrighted material --- fixing expressions of program, she generates new copyrighted material --- fixing expressions of
ideas into the tangible medium of electronic file storage. That ideas into the tangible medium of electronic file storage. That
programmer is indeed the copyright holder of those new changes. However, programmer is indeed the copyright holder of those new changes. However,
those changes are part and parcel to the original work distributed to those changes are part and parcel to the original work distributed to
the programmer under GPL\@. Thus, the license of the original work the programmer under GPL\@. Thus, the license of the original work
affects the license of the new whole derivative work. affects the license of the new whole derivative work.
@ -1503,7 +1504,7 @@ affects the license of the new whole derivative work.
\label{separate-and-independent} \label{separate-and-independent}
It is certainly possible to take an existing independent work (called It is certainly possible to take an existing independent work (called
\worki{}) and combine it with a GPL'd program (called \workg{}). The \worki{}) and combine it with a GPL'd program (called \workg{}). The
license of \worki{}, when it is distributed as a separate and independent license of \worki{}, when it is distributed as a separate and independent
work, remains the prerogative of the copyright holder of \worki{}. work, remains the prerogative of the copyright holder of \worki{}.
However, when \worki{} is combined with \workg{}, it produces a new work However, when \worki{} is combined with \workg{}, it produces a new work
@ -1512,95 +1513,93 @@ this combined work, \gplusi{}, is held by the original copyright
holder of each of the two works. holder of each of the two works.
In this case, GPLv2~\S2 lays out the terms by which \gplusi{} may be In this case, GPLv2~\S2 lays out the terms by which \gplusi{} may be
distributed and copied. By default, under copyright law, the copyright distributed and copied. By default, under copyright law, the copyright
holder of \worki{} would not have been permitted to distribute \gplusi{}; holder of \worki{} would not have been permitted to distribute \gplusi{};
copyright law forbids it without the expressed permission of the copyright copyright law forbids it without the expressed permission of the copyright
holder of \workg{}. (Imagine, for a moment, if \workg{} were a Microsoft holder of \workg{}. (Imagine, for a moment, if \workg{} were a proprietary
product --- would they give you permission to create and distribute product --- would its copyright holders give you permission to create and distribute
\gplusi{} without paying them a hefty sum?) The license of \workg{}, the \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{} GPL, states the options for the copyright holder of \worki{}
who may want to create and distribute \gplusi{}. This pregranted who may want to create and distribute \gplusi{}. GPL's pregranted
permission to create and distribute derivative works, provided the terms permission to create and distribute derivative works, provided the terms
of GPL are upheld, goes far above and beyond the permissions that one of GPL are upheld, goes far above and beyond the permissions that one
would get with a typical work not covered by a copyleft license. Thus, to 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. say that this restriction is any way unreasonable is simply ludicrous.)
\medskip \medskip
The next phrase of note in GPLv2~\S2(b) is ``licensed...at no charge.'' The next phrase of note in GPLv2~\S2(b) is ``licensed \ldots at no charge.''
This is a source of great confusion to many. Not a month goes by that This phrase confuses many. The sloppy reader points out this as ``a
FSF does not receive an email that claims to point out ``a contradiction in GPL'' because (in their confused view) that clause of GPLv2~\S2 says that redistributors cannot
contradiction in GPL'' because GPLv2~\S2 says that redistributors cannot
charge for modified versions of GPL'd software, but GPLv2~\S1 says that charge for modified versions of GPL'd software, but GPLv2~\S1 says that
they can. The ``at no charge'' does not prohibit redistributors from they can. Avoid this confusion: the ``at no charge'' \textbf{does not} prohibit redistributors from
charging when performing the acts governed by copyright charging when performing the acts governed by copyright
law,\footnote{Recall that you could by default charge for any acts not law,\footnote{Recall that you could by default charge for any acts not
governed by copyright law, because the license controls are confined governed by copyright law, because the license controls are confined
by copyright.} but rather that they cannot charge a fee for the by copyright.} but rather that they cannot charge a fee for the
\emph{license itself}. In other words, redistributors of (modified \emph{license itself}. In other words, redistributors of (modified
and unmodified) GPL'd works may charge any amount they choose for and unmodified) GPL'd works may charge any amount they choose for
performing the modifications on contract or the act of transferring performing the modifications on contract or the act of transferring
the copy to the customer, but they may not charge a separate licensing the copy to the customer, but they may not charge a separate licensing
fee for the software. fee for the software.
GPLv2~\S2(b) further states that the software must ``be licensed...to all GPLv2~\S2(b) further states that the software must ``be licensed \ldots to all
third parties.'' This too has led to some confusions, and feeds the third parties.'' This too yields some confusion, and feeds the
misconception mentioned earlier --- that all modified versions must made misconception mentioned earlier --- that all modified versions must made
available to the public at large. However, the text here does not say 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 that. Instead, it says that the licensing under terms of the GPL must
extend to anyone who might, through the distribution chain, receive a copy extend to anyone who might, through the distribution chain, receive a copy
of the software. Distribution to all third parties is not mandated here, of the software. Distribution to all third parties is not mandated here,
but GPLv2~\S2(b) does require redistributors to license the derivative works in but GPLv2~\S2(b) does require redistributors to license the derivative works in
a way that extends to all third parties who may ultimately receive a a way that extends to all third parties who may ultimately receive a
copy of the software. copy of the software.
In summary, GPLv2\ 2(b) says what terms under which the third parties must In summary, GPLv2\ 2(b) says what terms under which the third parties must
receive this no-charge license. Namely, they receive it ``under the terms receive this no-charge license. Namely, they receive it ``under the terms
of this License,'' the GPL. When an entity \emph{chooses} to redistribute of this License'', the GPLv2. When an entity \emph{chooses} to redistribute
a derivative work of GPL'd software, the license of that whole derivative a derivative work of GPL'd software, the license of that whole
work must be GPL and only GPL\@. In this manner, GPLv2~\S2(b) dovetails nicely work must be GPL and only GPL\@. In this manner, GPLv2~\S2(b) dovetails nicely
with GPLv2~\S6 (as discussed in Section~\ref{GPLv2s6} of this tutorial). with GPLv2~\S6 (as discussed in Section~\ref{GPLv2s6} of this tutorial).
\medskip \medskip
The final paragraph of GPLv2~\S2 is worth special mention. It is possible and The final paragraph of GPLv2~\S2 is worth special mention. It is possible and
quite common to aggregate various software programs together on one quite common to aggregate various software programs together on one
distribution medium. Computer manufacturers do this when they ship a distribution medium. Computer manufacturers do this when they ship a
pre-installed hard drive, and GNU/Linux distribution vendors do this to 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 give a one-stop CD or URL for a complete operating system with necessary
applications. The GPL very clearly permits such ``mere aggregation'' with applications. The GPL very clearly permits such ``mere aggregation'' with
programs under any license. Despite what you hear from its critics, the 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 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'd a virus is bad for you, but also because simple contact with a GPL'd
code-base does not impact the license of other programs. Actual effort code-base does not impact the license of other programs. A programmer must
must be expended by a programmer to cause a work to fall under the terms expended actual effort to cause a work to fall under the terms
of the GPL. Redistributors are always welcome to simply ship GPL'd of the GPL. Redistributors are always welcome to simply ship GPL'd
software alongside proprietary software or other unrelated Free Software, software alongside proprietary software or other unrelated Free Software,
as long as the terms of GPL are adhered to for those packages that are as long as the terms of GPL are adhered to for those packages that are
truly GPL'd. truly GPL'd.
\section{GPLv2~\S3: Producing Binaries} \section{GPLv2~\S3: Producing Binaries}
\label{GPL-Section-3} \label{GPL-Section-3}
% FIXME: need name of a novelist who writes very obscurely and obliquely.
Software is a strange beast when compared to other copyrightable works. Software is a strange beast when compared to other copyrightable works.
It is currently impossible to make a film or a book that can be truly It is currently impossible to make a film or a book that can be truly
obscured. Ultimately, the full text of a novel, even one written by obscured. Ultimately, the full text of a novel, even one written by
William Faulkner, must presented to the reader as words in some William Faulkner, must presented to the reader as words in some
human-readable language so that they can enjoy the work. A film, even one human-readable language so that they can enjoy the work. A film, even one
directed by David Lynch, must be perceptible by human eyes and ears to directed by David Lynch, must be perceptible by human eyes and ears to
have any value. have any value.
Software is not so. While the source code, the human-readable Software is not so. While the source code --- the human-readable
representation of software is of keen interest to programmers, users and representation of software is of keen interest to programmers -- users and
programmers alike cannot make the proper use of software in that programmers alike cannot make the proper use of software in that
human-readable form. Binary code --- the ones and zeros that the computer human-readable form. Binary code --- the ones and zeros that the computer
can understand --- must be predicable and attainable for the software to can understand --- must be predicable and attainable for the software to
be fully useful. Without the binaries, be they in object or executable be fully useful. Without the binaries, be they in object or executable
form, the software serves only the didactic purposes of computer science. form, the software serves only the didactic purposes of computer science.
Under copyright law, binary representations of the software are simply Under copyright law, binary representations of the software are simply
derivative works of the source code. Applying a systematic process (i.e., derivative works of the source code. Applying a systematic process (i.e.,
``compilation'') to a work of source code yields binary code. The binary ``compilation'') to a work of source code yields binary code. The binary
code is now a new work of expression fixed in the tangible medium of code is now a new work of expression fixed in the tangible medium of
electronic file storage. electronic file storage.