\href{http://www.copyright.gov/title17/92chap1.html#106}{\S~106} and

\href{http://www.copyright.gov/title17/92chap1.html#117}{\S~117} of

\href{http://www.law.cornell.edu/uscode/text/17/102}{17 USC \S~102}), is thus

\href{http://www.law.cornell.edu/uscode/text/17/105}{17 USC 101 \S~105}, all

  (in part) the addition of GPLv2~\S\S5--7.  (These sections are discussed in

\item GPLv2~\S2's copyleft terms are expanded to more explicitly discuss the

  issue of combined works.  (GPLv2~\S2 is discussed in detail in

\item GPLv2~\S3 includes more detailed requirements, including the phrase

  .  (GPLv2~\S3 is discussed in detail in

\section{GPLv2~\S0: Freedom to Run}

GPLv2~\S0, the opening section of GPLv2, sets forth that the copyright law governs

A bit more subtly, GPLv2~\S0 makes an inference that copyright law is the only

Thus, users are explicitly given the freedom to run by GPLv2~\S0.

The bulk of GPLv2~\S0 not yet discussed gives definitions for other terms used

\section{GPLv2~\S1: Verbatim Copying}

GPLv2~\S1 covers the matter of redistributing the source code of a program

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

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

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

specifically in GPLv2~\S1.  These are in some ways the most important part of

Note finally that GPLv2~\S1 begins to set forth the important defense of

commercial freedom. GPLv2~\S1 clearly states that in the case of verbatim

understand fully before considering GPLv2~\S\S2--3\@. GPL, and Free

applicable Free Software license. As much is required by \S~106 of the

Copyright Act, 17 U.S.C. \S~106 (2002), and admitted by Free Software

licenses, such as the GPL, which (as we have seen) states in GPLv2~\S0 that ``a

the definition of derivative work is \S~102(b), which reads as follows:

First, as set forth in \S~102(b) of the Copyright Act, any and all ideas

First Circuit holds that ``method of operation,'' as used in \S~102(b) of

the unprotectable elements set forth in \S~102(b) broadly, and, as such,

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

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

freedom along the distribution chain. GPLv2~\S2 is the only place in the GPL

modifies a GPL'd program, she is bound in the making those changes by

GPLv2~\S2.  The goal here is to ensure that the body of GPL'd software, as it

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

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

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

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

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

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

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

considered by some to be the most worthy of careful scrutiny because GPLv2~\S2(b)

can be a source of great confusion when not properly understood.

In considering GPLv2~\S2(b), first note the qualifier: it only applies to

share their changes. On the contrary, GPLv2~\S2(b) {\bf does not apply if} the

Next, we again encounter the same matter that appears in GPLv2~\S0, in the

derived from'' the GPL'd software, then the requirements of GPLv2~\S2(b)

The final clause of GPLv2~\S2(b) describes what the licensee must do if she is

point that GPLv2~\S2 spends an entire paragraph explaining; thus this phrase is

In this case, GPLv2~\S2 lays out the terms by which \gplusi{} may be

The next phrase of note in GPLv2~\S2(b) is ``licensed...at no charge.''

contradiction in GPL'' because GPLv2~\S2 says that redistributors cannot

charge for modified versions of GPL'd software, but GPLv2~\S1 says that

GPLv2~\S2(b) further states that the software must ``be licensed...to all

but GPLv2~\S2(b) does require redistributors to license the derivative works in

In summary, GPLv2\ 2(b) says what terms under which the third parties must

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).

The final paragraph of GPLv2~\S2 is worth special mention. It is possible and

\section{GPLv2~\S3: Producing Binaries}

source code. GPLv2~\S3 addresses the matter of creation and distribution of

Under GPLv2~\S3, binary versions may be created and distributed under the

terms of GPLv2~\S1--2, so all the material previously discussed applies

here. However, GPLv2~\S3 must go a bit further. Access to the software's

effectively impossible. GPLv2~\S3 must ensure that the binaries are never

GPLv2~\S3 permits distribution of binaries, and then offers three options for

least complicated is the option given under GPLv2~\S3(a).

GPLv2~\S3(a) offers the option to directly accompany the source code alongside

Under GPLv2~\S3(a), the source code provided must be the ``corresponding source

That source code must also be ``complete.''  A later paragraph of GPLv2~\S3

Furthermore, GPLv2~\S3 is defending against a tactic that has in fact been

Therefore, GPLv2~\S3 requires that the source code include ``meta-material'' like

GPLv2~\S3, therefore, allows source code to be provided on any physical

of GPLv2~\S3. \emph{If} distribution of the binary files is made only on the

sufficient to comply with GPLv2~\S3.

As is shown above, Under GPLv2~\S3(a), embedded manufacturers can put the

GPLv2~\S3(b) allows a distributor of binaries to instead provide a written

and environmental windfall. In addition, along with a GPLv2~\S3(b) compliant

source online, GPLv2~\S3(b) does place lasting long-term obligations on the

would have had to do under GPLv2~\S3(a)) at a moment's notice when they

redistribution granted by GPLv2~\S\S1--2. A company may ship a binary image

GPLv2~\S3(c) is created to save her some trouble, because by itself GPLv2~\S3(b)

would unfairly favor large companies. GPLv2~\S3(b) allows the

Meanwhile, GPLv2~\S3(b)'s compromise primarily benefits companies who

distribute binary software commercially. Without GPLv2~\S3(c), that benefit

customers. A customer, who had received binaries with a GPLv2~\S3(b)-compliant

offer, would be required under GPLv2 (sans GPLv2~\S3(c)) to acquire the source,

merely to give a copy of the software to a friend who needed it. GPLv2~\S3(c)

reshifts this burden to entity who benefits from GPLv2~\S3(b).

GPLv2~\S3(c) allows those who undertake \emph{noncommercial} distribution to

simply pass along a GPLv2~\S3(b)-compliant source code offer. The customer who

she would have to acquire the source and either comply via GPLv2~\S3(a), or

write her own GPLv2~\S3(b)-compliant source offer.

This process is precisely the reason why a GPLv2~\S3(b) source offer must be

software. Companies who choose to comply via GPLv2~\S3(b) must thus be

many other additional necessary complications under GPLv2~\S\S3(b--c), it is

only rarely a better option than complying via GPLv2~\S3(a).

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

4--7 of the GPLv2 are designed to ensure that GPLv2~\S\S0--3 are not infringed,

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

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

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

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

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),

GPLv2~\S4 gives GPLv2 teeth. If licensees fail to adhere to the license, then

\section{GPLv2~\S5: Acceptance, Copyright Style}

GPLv2~\S5 brings us to perhaps the most fundamental misconception and common

An interesting side benefit to GPLv2~\S5 is that the bulk of users of Free

\section{GPLv2~\S6: GPL, My One and Only}

A point that was glossed over in Section~\ref{GPLv2s4}'s discussion of GPLv2~\S4

and it is made so formally by GPLv2~\S6.

The first sentence in GPLv2~\S6 ensures that as software propagates down the

new licensee. Under GPLv2~\S6, the act of distributing automatically grants a

The second sentence of GPLv2~\S6 does the opposite; it bounds from the top. It

The final sentence of GPLv2~\S6 makes it abundantly clear that no individual

passed along a source offer under GPLv2~\S3(c), as they cannot be assured that

the issuer of the offer will honor their GPLv2~\S3 obligations.

In short, GPLv2~\S6 says that your license for the software is your one and

\section{GPLv2~\S7: ``Give Software Liberty or Give It Death!''}

In essence, GPLv2~\S7 is a verbosely worded way of saying for non-copyright

systems what GPLv2~\S6 says for copyright. If there exists any reason that a

Thus, GPLv2~\S7 rarely gives software death by stopping its distribution.

\section{GPLv2~\S8: Excluding Problematic Jurisdictions}

GPLv2~\S8 is rarely used by copyright holders. Its intention is that if a

It is a partial ``out'' from GPLv2~\S7. Without GPLv2~\S8, if a copyright holder

others. GPLv2~\S8 exists to permit distribution in those countries that are

GPLv2~\S\S0--7 constitute the freedom-defending terms of the GPLv2. The remainder

\section{GPLv2~\S9: FSF as Stewards of GPL}

GPLv2~\S9 expresses this. While the stewardship of the copyrights on the body

\section{GPLv2~\S10: Relicensing Permitted}

GPLv2~\S10 reminds the licensee of what is already implied by the nature of

\section{GPLv2~\S11: No Warranty}

its disclaimer of warranties is impermissibly broad. However, GPLv2~\S11

Finally, one important point to remember when reading GPLv2~\S11 is that GPLv2~\S1

permits the sale of warranty as an additional service, which GPLv2~\S11 affirms.

\section{GPLv2~\S12: Limitation of Liability}

warranty disclaimer and a limitation of liability, as we have in GPLv2~\S12. \S

disavowed. GPLv2~\S12, in turn, limits the liability of the actor for any

12, just like its sister, GPLv2~\S11, contains a jurisdictional savings

both GPLv2~\S12, and the entire GPL, is enforceable in any jurisdiction,

\section{GPLv3~\S0: Giving In On ``Defined Terms''}

\section{GPLv3~\S1: Understanding CCS}

\section{GPLv3~\S2: Basic Permissions}

\section{GPLv3~\S3: What Hath DMCA Wrought}

\section{GPLv3~\S4: Verbatim Copying}

\section{GPLv3~\S5: Modified Source}

\section{GPLv3~\S6: Non-Source and Corresponding Source}

\section{GPLv3~\S7: Explicit Compatibility}

\section{GPLv3~\S8: A Lighter Termination}

\section{GPLv3~\S9: Acceptance}

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

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

\section{GPLv3~\S12: Familiar as GPLv2 \S 7}

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

\section{GPLv3~\S14: So, When's GPLv4?}

\section{GPLv3~\S15--17: Warranty Disclaimers and Liability Limitation}

First, LGPLv2.1~\S1, the rules for verbatim copying of source, are

equivalent to those in GPLv2~\S1.

Second, LGPLv2.1~\S8 is equivalent GPLv2~\S4\@. In both licenses, this

LGPLv2.1~\S9 is equivalent to GPLv2~\S5\@. Both sections assert that

LGPLv2.1~\S10 is equivalent to GPLv2~\S6. They both protect the

LGPLv2.1~\S11 is GPLv2~\S7. As discussed, it is used to ensure that

LGPLv2.1~\S12 adds the same features as GPLv2~\S8. These sections are

LGPLv2.1~\S13 sets up FSF as the steward of the LGPL, just as GPLv2~\S9

does for GPL. Meanwhile, LGPLv2.1~\S14 reminds licensees that copyright

holders can grant exceptions to the terms of LGPL, just as GPLv2~\S10

identical; thus LGPLv2.1~\S15 and LGPLv2.1~\S16 are the same as GPLv2~\S11 and \S

of a ``work that uses the library,'' which is set forth in LGPLv2.1~\S5.

We noted in our discussion of GPLv2~\S3 (discussed in

binary derivative works are controlled by the terms of the license (in GPLv2~\S3),

and distributors of such binary derivatives must release full

We will talk about the specific restrictions LGPLv2.1 places on ``works

now, focus on the logic related to how the LGPLv2.1 places requirements on

works with GPL'd code. Effectively, what LGPLv2.1 does is say that when a

In addition, the only reason that LGPLv2.1 has any control over the licensing

the LGPLv2.1'd software (\workl{}).

a ``work that uses the library'' under LGPLv2.1 is as follows:

In our years of work with the LGPLv2.1, however, we have never seen a work

considered independently and the LGPLv2.1 applied to each work as

details. The fourth paragraph of LGPLv2.1~\S5 covers these complexities,

mandatory to grasp the subtle nature of what LGPLv2.1~\S5, \P 4 seeks to

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

\item Allowing a licensing ``upgrade'' from LGPL to GPL\@ (in LGPLv2.1~\S3)

\item Binary distribution of the library only, covered in LGPLv2.1~\S4,

  which is effectively equivalent to LGPLv2.1~\S3

  each other, and distributing them as a unit (in LGPLv2.1~\S7)

but they are mostly straightforward. The key to understanding LGPLv2.1 is

remainder of LGPLv2.1 is close enough to GPL that the concepts discussed in

enterprise, such copying is not only permitted by GPLv2~\S\S1 and 3, but it is