gpl-lgpl.tex 280 KB

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  1. % gpl-lgpl.tex -*- LaTeX -*-
  2. % Tutorial Text for the Detailed Study and Analysis of GPL and LGPL course
  3. %
  4. % License: CC-By-SA-4.0
  5. % The copyright holders hereby grant the freedom to copy, modify, convey,
  6. % Adapt, and/or redistribute this work under the terms of the Creative
  7. % Commons Attribution Share Alike 4.0 International License.
  8. % This text is distributed in the hope that it will be useful, but
  9. % WITHOUT ANY WARRANTY; without even the implied warranty of
  10. % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  11. % You should have received a copy of the license with this document in
  12. % a file called 'CC-By-SA-4.0.txt'. If not, please visit
  13. % https://creativecommons.org/licenses/by-sa/4.0/legalcode to receive
  14. % the license text.
  15. % FIXME-LATER: I should make a macro like the Texinfo @xref stuff for places
  16. % where I'm saying ``see section X in this tutorial'', so that the extra
  17. % verbiage isn't there in the HTML versions that I'll eventually do.
  18. % Maybe something like that already exists? In the worst case, I could
  19. % adapt @xref from texinfo.texi for it.
  20. \newcommand{\defn}[1]{\emph{#1}}
  21. \part{Detailed Analysis of the GNU GPL and Related Licenses}
  22. \label{gpl-lgpl-part}
  23. \tutorialpartsplit{This tutorial}{This part of the tutorial} gives a
  24. comprehensive explanation of the most popular Free Software copyright
  25. license, the GNU General Public License (``GNU GPL'', or sometimes just
  26. ``GPL'') -- both version 2 (``GPLv2'') and version 3 (``GPLv3'') -- and
  27. teaches lawyers, software developers, managers and businesspeople how to use
  28. the GPL (and GPL'd software) successfully both as a community-building
  29. ``Constitution'' for a software project, and to incorporate copylefted
  30. software into a new Free Software business and in existing, successful
  31. enterprises.
  32. To benefit from this part of the tutorial, readers should
  33. have a general familiarity with software development processes. A basic
  34. understanding of how copyright law applies to software is also helpful. The
  35. tutorial is of most interest to lawyers, software developers and managers who
  36. run or advise software businesses that modify and/or redistribute software
  37. under the terms of the GNU GPL (or who wish to do so in the future), and those
  38. who wish to make use of existing GPL'd software in their enterprise.
  39. Upon completion of this part of the tutorial, readers can expect
  40. to have learned the following:
  41. \begin{itemize}
  42. \item The freedom-defending purpose of various terms in the GNU GPLv2 and GPLv3.
  43. \item The differences between GPLv2 and GPLv3.
  44. \item The redistribution options under the GPLv2 and GPLv3.
  45. \item The obligations when modifying GPLv2'd or GPLv3'd software.
  46. \item How to build a plan for proper and successful compliance with the GPL.
  47. \item The business advantages that the GPL provides.
  48. \item The most common business models used in conjunction with the GPL.
  49. \item How existing GPL'd software can be used in existing enterprises.
  50. \item The basics of LGPLv2.1 and LGPLv3, and how they
  51. differ from the GPLv2 and GPLv3, respectively.
  52. \item The basics to begin understanding the complexities regarding
  53. derivative and combined works of software.
  54. \end{itemize}
  55. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  56. % END OF ABSTRACTS SECTION
  57. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  58. % START OF DAY ONE COURSE
  59. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  60. \chapter{What Is Software Freedom?}
  61. Study of the GNU General Public License (herein, abbreviated as \defn{GNU
  62. GPL} or just \defn{GPL}) must begin by first considering the broader world
  63. of software freedom. The GPL was not created in a vacuum. Rather, it was
  64. created to embody and defend a set of principles that were set forth at the
  65. founding of the GNU Project and the Free Software Foundation (FSF) -- the
  66. preeminent organization that upholds, defends and promotes the philosophy of software
  67. freedom. A prerequisite for understanding both of the popular versions
  68. of the GPL
  69. (GPLv2 and GPLv3) and their terms and conditions is a basic understanding of
  70. the principles behind them. The GPL family of licenses are unlike nearly all
  71. other software licenses in that they are designed to defend and uphold these
  72. principles.
  73. \section{The Free Software Definition}
  74. \label{Free Software Definition}
  75. The Free Software Definition is set forth in full on FSF's website at
  76. \verb0http://fsf.org/0 \verb0philosophy/free-sw.html0. This section presents
  77. an abbreviated version that will focus on the parts that are most pertinent
  78. to the GPL\@.
  79. A particular user has software freedom with respect to a particular program if that
  80. user has the following freedoms:
  81. \begin{itemize}
  82. \item The freedom to run the program, for any purpose.
  83. \item The freedom to study how the program works, and modify it
  84. \item The freedom to redistribute copies.
  85. \item The freedom to distribute copies of modified versions to others.
  86. \end{itemize}
  87. The focus on ``a particular user'' is particularly pertinent here. It is not
  88. uncommon for a subset of a specific program's user base to have these freedoms, while other
  89. users of the same version the program have none or only some of these freedoms.
  90. Section~\ref{Proprietary Relicensing} talks in detail about how
  91. this can unfortunately happen even if a program is released under the GPL\@.
  92. Many people refer to software with these freedoms as ``Open Source.''
  93. Besides having a different political focus from those who call such software
  94. by the name ``Free
  95. Software'',\footnote{The political differences between the Free Software
  96. Movement and the Open Source Movement are documented on FSF's Web site at
  97. \url{http://www.fsf.org/licensing/essays/free-software-for-freedom.html}.},
  98. those who call the software ``Open Source'' are often focused on a side
  99. issue. Specifically, user access to the source code of a program is a
  100. prerequisite to make use of the freedom to modify. However, the important
  101. issue is what freedoms are granted in the license that applies to that source code.
  102. Software freedom is only complete when no restrictions are imposed on how
  103. these freedoms are exercised. Specifically, users and programmers can
  104. exercise these freedoms noncommercially or commercially. Licenses that grant
  105. these freedoms for noncommercial activities but prohibit them for commercial
  106. activities are considered non-free. The Open Source Initiative
  107. (\defn{OSI}) (the arbiter of what is considered ``Open Source'') also regards
  108. such licenses as inconsistent with its ``Open Source Definition''.
  109. In general, software for which any of these freedoms are restricted in any
  110. way is called ``nonfree'' software. Some use the term ``proprietary
  111. software'' more or less interchangeably with ``nonfree software''. The FSF
  112. published a useful
  113. \href{http://www.gnu.org/philosophy/categories.html}{explanation of various
  114. types of software and how they relate to one another}.
  115. Keep in mind that none of the terms ``software freedom'', ``open source''
  116. and ``free software'' are known to be trademarked or otherwise legally
  117. restricted by any organization in
  118. any jurisdiction. As such, it's quite common that these terms are abused and
  119. misused by parties who wish to bank on the popularity of software freedom.
  120. When one considers using, modifying or redistributing a software package that
  121. purports to be Open Source or Free Software, one \textbf{must} verify that
  122. the license grants software freedom.
  123. Furthermore, throughout this text, we generally prefer the term ``software
  124. freedom'', as this is the least ambiguous term available to describe software
  125. that meets the Free Software Definition. For example, it is well known and
  126. often discussed that the adjective ``free'' has two unrelated meanings in
  127. English: ``free as in freedom'' and ``free as in price''. Meanwhile, the
  128. term ``open source'' is even more confusing, because it appears to refer only to the
  129. ``freedom to study'', which is merely a subset of one of the four freedoms.
  130. The remainder of this section considers each of each component of software
  131. freedom in detail.
  132. \subsection{The Freedom to Run}
  133. \label{freedom-to-run}
  134. The first tenet of software freedom is the user's fully unfettered right to
  135. run the program. The software's license must permit any conceivable use of
  136. the software. Perhaps, for example, the user has discovered an innovative
  137. use for a particular program, one that the programmer never could have
  138. predicted. Such a use must not be restricted.
  139. It was once rare that this freedom was restricted by even proprietary
  140. software; but such is quite common today. Most End User License Agreements
  141. (EULAs) that cover most proprietary software typically restrict some types of
  142. uses. Such restrictions of any kind are an unacceptable restriction on
  143. software freedom.
  144. \subsection{The Freedom to Change and Modify}
  145. Perhaps the most useful right of software freedom is the users' right to
  146. change, modify and adapt the software to suit their needs. Access to the
  147. source code and related build and installation scripts are an essential part
  148. of this freedom. Without the source code, and the ability to build and
  149. install the binary applications from that source, users cannot effectively
  150. exercise this freedom.
  151. Programmers directly benefit from this freedom. However, this freedom
  152. remains important to users who are not programmers. While it may seem
  153. counterintuitive at first, non-programmer users often exercise this freedom
  154. indirectly in both commercial and noncommercial settings. For example, users
  155. often seek noncommercial help with the software on email lists and in user
  156. groups. To make use of such help they must either have the freedom to
  157. recruit programmers who might altruistically assist them to modify their
  158. software, or to at least follow rote instructions to make basic modifications
  159. themselves.
  160. More commonly, users also exercise this freedom commercially. Each user, or
  161. group of users, may hire anyone they wish in a competitive free market to
  162. modify and change the software. This means that companies have a right to
  163. hire anyone they wish to modify their Free Software. Additionally, such
  164. companies may contract with other companies to commission software
  165. modifications.
  166. \subsection{The Freedom to Copy and Share}
  167. Users share Free Software in a variety of ways. Software freedom advocates
  168. work to eliminate a fundamental ethical dilemma of the software age: choosing
  169. between obeying a software license and friendship (by giving away a copy of a
  170. program to your friend who likes the software you are using). Licenses that
  171. respect software freedom, therefore, permit altruistic sharing of software
  172. among friends.
  173. The commercial environment also benefits from this freedom. Commercial sharing
  174. includes selling copies of Free Software: that is, Free Software can
  175. be distributed for any monetary
  176. price to anyone. Those who redistribute Free Software commercially also have
  177. the freedom to selectively distribute (i.e., you can pick your customers) and
  178. to set prices at any level that redistributor sees fit.
  179. Of course, most people get copies of Free Software very cheaply (and
  180. sometimes without charge). The competitive free market of Free Software
  181. tends to keep prices low and reasonable. However, if someone is willing to
  182. pay billions of dollars for one copy of the GNU Compiler Collection, such a
  183. sale is completely permitted.
  184. Another common instance of commercial sharing is service-oriented
  185. distribution. For example, some distribution vendors provide immediate
  186. security and upgrade distribution via a special network service. Such
  187. distribution is not necessarily contradictory with software freedom.
  188. (Section~\ref{Business Models} of this tutorial talks in detail about some
  189. common Free Software business models that take advantage of the freedom to
  190. share commercially.)
  191. \subsection{The Freedom to Share Improvements}
  192. The freedom to modify and improve is somewhat empty without the freedom to
  193. share those improvements. The software freedom community is built on the
  194. pillar of altruistic sharing of improved Free Software. Historically
  195. it was typical for a
  196. Free Software project to sprout a mailing list where improvements
  197. would be shared
  198. freely among members of the development community.\footnote{This is still
  199. commonly the case, though today there are additional ways of
  200. sharing Free Software.} Such noncommercial
  201. sharing is the primary reason that Free Software thrives.
  202. Commercial sharing of modified Free Software is equally important.
  203. For commercial support to exist in a competitive free market, all
  204. developers -- from single-person contractors to large software
  205. companies -- must have the freedom to market their services as
  206. augmenters of Free Software. All forms of such service marketing must
  207. be equally available to all.
  208. For example, selling support services for Free Software is fully
  209. permitted. Companies and individuals can offer themselves as ``the place
  210. to call'' when software fails or does not function properly. For such a
  211. service to be meaningful, the entity offering that service needs the
  212. right to modify and improve the software for the customer to correct any
  213. problems that are beyond mere user error.
  214. Software freedom licenses also permit any entity to distribute modified
  215. versions of Free Software. Most Free Software programs have a ``standard
  216. version'' that is made available from the primary developers of the software.
  217. However, all who have the software have the ``freedom to fork'' -- that is,
  218. make available nontrivial modified versions of the software on a permanent or
  219. semi-permanent basis. Such freedom is central to vibrant developer and user
  220. interaction.
  221. Companies and individuals have the right to make true value-added versions
  222. of Free Software. They may use freedom to share improvements to
  223. distribute distinct versions of Free Software with different functionality
  224. and features. Furthermore, this freedom can be exercised to serve a
  225. disenfranchised subset of the user community. If the developers of the
  226. standard version refuse to serve the needs of some of the software's
  227. users, other entities have the right to create a long- or short-lived fork
  228. to serve that sub-community.
  229. \section{How Does Software Become Free?}
  230. The previous section set forth key freedoms and rights that are referred to
  231. as ``software freedom''. This section discusses the licensing mechanisms
  232. used to enable software freedom. These licensing mechanisms were ultimately
  233. created as a community-oriented ``answer'' to the existing proprietary
  234. software licensing mechanisms. Thus, first, consider carefully why
  235. proprietary software exists in the first place.
  236. \label{explaining-copyright}
  237. The primary legal regime that applies to software is copyright law.
  238. Proprietary software exists at all only because copyright law governs
  239. software.\footnote{This statement is admittedly an oversimplification. Patents and
  240. trade secrets can cover software and make it effectively non-Free, and one
  241. can contract away their rights and freedoms regarding software, or source
  242. code can be practically obscured in binary-only distribution without
  243. reliance on any legal system. However, the primary control mechanism for
  244. software is copyright, and therefore this section focuses on how copyright
  245. restrictions make software proprietary.} Copyright law, with respect to
  246. software, typically governs copying, modifying, and redistributing that
  247. software (For details of this in the USA, see
  248. \href{http://www.copyright.gov/title17/92chap1.html#106}{\S~106} and
  249. \href{http://www.copyright.gov/title17/92chap1.html#117}{\S~117} of
  250. \href{http://www.law.cornell.edu/uscode/text/17}{Title 17} of the
  251. \textit{United States Code}).\footnote{Copyright law in general also governs
  252. ``public performance'' of copyrighted works. There is no generally agreed
  253. definition for public performance of software and both GPLv2 and GPLv3 do
  254. not restrict public performance.} By law (in the USA and in most other
  255. jurisdictions), the copyright holder (most typically, the author) of the work controls
  256. how others may copy, modify and/or distribute the work. For proprietary
  257. software, these controls are used to prohibit these activities. In addition,
  258. proprietary software distributors further impede modification in a practical
  259. sense by distributing only binary code and keeping the source code of the
  260. software secret.
  261. Copyright is not a natural state, it is a legal construction. In the USA, the
  262. Constitution permits, but does not require, the creation of copyright law as
  263. federal legislation. Software, since it is an ``original work of authorship
  264. fixed in any tangible medium of expression ... from which they can be
  265. perceived, reproduced, or otherwise communicated, either directly or with the
  266. aid of a machine or device'' (as stated in
  267. \href{http://www.law.cornell.edu/uscode/text/17/102}{17 USC \S~102}), is thus
  268. covered by the statute, and is copyrighted by default.
  269. However, software, in its natural state without copyright, is Free
  270. Software. In an imaginary world with no copyright, the rules would be
  271. different. In this world, when you received a copy of a program's source
  272. code, there would be no default legal system to restrict you from sharing it
  273. with others, making modifications, or redistributing those modified
  274. versions.\footnote{Note that this is again an oversimplification; the
  275. complexities with this argument are discussed in
  276. Section~\ref{software-and-non-copyright}.}
  277. Software in the real world is copyrighted by default and is automatically
  278. covered by that legal system. However, it is possible to move software out
  279. of the domain of the copyright system. A copyright holder can often
  280. \defn{disclaim} their copyright. (For example, under USA copyright law
  281. it is possible for a copyright holder to engage in conduct resulting
  282. in abandonment of copyright.) If copyright is disclaimed, the software is
  283. effectively no longer restricted by copyright law. Software not restricted by copyright is in the
  284. ``public domain.''
  285. \subsection{Public Domain Software}
  286. In the USA and other countries that
  287. are parties to the Berne Convention on Copyright, software is copyrighted
  288. automatically by the author when she fixes the software in a tangible
  289. medium. In the software world, this usually means typing the source code
  290. of the software into a file.
  291. Imagine if authors could truly disclaim those default controls of copyright
  292. law. If so, the software is in the public domain --- no longer covered by
  293. copyright. Since copyright law is the construction allowing for most
  294. restrictions on software (i.e., prohibition of copying, modification, and
  295. redistribution), removing the software from the copyright system usually
  296. yields software freedom for its users.
  297. Carefully note that software truly in the public domain is \emph{not} licensed
  298. in any way. It is confusing to say software is ``licensed for the
  299. public domain,'' or any phrase that implies the copyright holder gave
  300. express permission to take actions governed by copyright law.
  301. Copyright holders who state that they are releasing their code into
  302. the public domain are effectively renouncing copyright controls on
  303. the work. The law gave the copyright holders exclusive controls over the
  304. work, and they chose to waive those controls. Software that is, in
  305. this sense, in the public domain
  306. is conceptualized by the developer as having no copyright and thus no license. The software freedoms discussed in
  307. Section~\ref{Free Software Definition} are all granted because there is no
  308. legal system in play to take them away.
  309. Admittedly, a discussion of public domain software is an oversimplified
  310. example.
  311. Because copyright controls are usually automatically granted and because, in
  312. some jurisdictions, some copyright controls cannot be waived (see
  313. Section~\ref{non-usa-copyright} for further discussion), many copyright
  314. holders sometimes incorrectly believe a work has been placed in the public
  315. domain. Second, due to aggressive lobbying by the entertainment industry,
  316. the ``exclusive Right'' of copyright, that was supposed to only exist for
  317. ``Limited Times'' according to the USA Constitution, appears to be infinite:
  318. simply purchased on the installment plan rather than in whole. Thus, we must
  319. assume no works of software will fall into the public domain merely due to
  320. the passage of time.
  321. Nevertheless, under USA law it is likely that the typical
  322. disclaimers of copyright or public domain dedications we see in the
  323. Free Software world would be interpreted by courts as copyright
  324. abandonment, leading to a situation in which the user effectively receives a
  325. maximum grant of copyright freedoms, similar to a maximally-permissive
  326. Free Software license.
  327. The best example of software known to truly be in the public domain is software
  328. that is published by the USA government. Under
  329. \href{http://www.law.cornell.edu/uscode/text/17/105}{17 USC 101 \S~105}, all
  330. works published by the USA Government are not copyrightable in the USA.
  331. \subsection{Why Copyright Free Software?}
  332. If simply disclaiming copyright on software yields Free Software, then it
  333. stands to reason that putting software into the public domain is the
  334. easiest and most straightforward way to produce Free Software. Indeed,
  335. some major Free Software projects have chosen this method for making their
  336. software Free. However, most of the Free Software in existence \emph{is}
  337. copyrighted. In most cases (particularly in those of FSF and the GNU
  338. Project), this was done due to very careful planning.
  339. Software released into the public domain does grant freedom to those users
  340. who receive the standard versions on which the original author disclaimed
  341. copyright. However, since the work is not copyrighted, any nontrivial
  342. modification made to the work is fully copyrightable.
  343. Free Software released into the public domain initially is Free, and
  344. perhaps some who modify the software choose to place their work into the
  345. public domain as well. However, over time, some entities will choose to
  346. proprietarize their modified versions. The public domain body of software
  347. feeds the proprietary software. The public commons disappears, because
  348. fewer and fewer entities have an incentive to contribute back to the
  349. commons. They know that any of their competitors can proprietarize their
  350. enhancements. Over time, almost no interesting work is left in the public
  351. domain, because nearly all new work is done by proprietarization.
  352. A legal mechanism is needed to redress this problem. FSF was in fact
  353. originally created primarily as a legal entity to defend software freedom,
  354. and that work of defending software freedom is a substantial part of
  355. its work today. Specifically because of this ``embrace, proprietarize and
  356. extend'' cycle, FSF made a conscious choice to copyright its Free Software,
  357. and then license it under ``copyleft'' terms. Many, including the
  358. developers of the kernel named Linux, have chosen to follow this paradigm.
  359. \label{copyleft-definition}
  360. Copyleft is a strategy of utilizing copyright law to pursue the policy goal
  361. of fostering and encouraging the equal and inalienable right to copy, share,
  362. modify and improve creative works of authorship. Copyleft (as a general
  363. term) describes any method that utilizes the copyright system to achieve the
  364. aforementioned goal. Copyleft as a concept is usually implemented in the
  365. details of a specific copyright license, such as the
  366. \hyperref[GPLv3-full-text]{GNU General Public License (GPL)} and the Creative
  367. Commons Attribution Share Alike License (the latter of which is the license
  368. of this work itself). Copyright holders of creative work can unilaterally
  369. implement these licenses for their own works to build communities that
  370. collaboratively share and improve those copylefted creative works.
  371. Copyleft uses functional parts of the copyright system to achieve an unusual
  372. result (legal protection for free sharing). Copyleft modifies, or ``hacks''
  373. copyright law, which is usually employed to strengthen the rights of authors
  374. or publishers, to strengthen instead the rights of users. Thus, Copyleft is
  375. a legal strategy and mechanism to defend, uphold and propagate software
  376. freedom. The basic technique of copyleft is as follows: copyright the
  377. software, license it under terms that give all the software freedoms, but use
  378. the copyright law controls to ensure that all who receive a copy of the
  379. software have equal rights and freedom. In essence, copyleft grants freedom,
  380. but forbids others to forbid that freedom to anyone else along the
  381. distribution and modification chains.
  382. Copyleft's ``reciprocity'' or ``share and share alike'' rule protects both
  383. developers, who avoid facing a ``prioritized'' competitor of their project,
  384. and users, who can be sure that they will have all four software freedoms ---
  385. not only in the present version of the program they use, but in all its
  386. future improved versions.
  387. Copyleft is a general concept. Much like ideas for what a computer might
  388. do must be \emph{implemented} by a program that actually does the job, so
  389. too must copyleft be implemented in some concrete legal structure.
  390. ``Share and share alike'' is a phrase that is used often enough to explain the
  391. concept behind copyleft, but to actually make it work in the real world, a
  392. true implementation in legal text must exist, written as a ``copyright
  393. license''. The GPL implements the concept of copyleft for software-oriented
  394. and other functional works of a technical nature. The ``CC BY SA'' license
  395. implements copyleft for works of textual, musical and visual authorship, such
  396. as this tutorial.
  397. Copyleft advocates often distinguish between the concept of a ``strong
  398. copyleft'' or a ``weak copyleft''. However, ``strong vs. weak'' copyleft is
  399. not a dichotomy, it's a spectrum. The strongest copylefts strive to the
  400. exclusive rights that copyright grants to authors as extensively as possible
  401. to maximize software freedom. As a copyleft gets ``weaker'', the copyleft
  402. license typically makes ``trade offs'' that might impede software freedom,
  403. but reach other tactic goals for the community of users and developers of the
  404. work.
  405. In other words, strong copyleft licenses place the more requirements on how
  406. ``the work'' is licensed. The unit of copyright law is ``the work''. In
  407. that sense, the ``work'' referenced by the licenses is anything that can be
  408. copyrighted or will be subject to the terms of copyright law. Strong
  409. copyleft licenses exercise their scope fully. Anything which is ``a work''
  410. or a ``work based on a work'' licensed under a strong copyleft is subject to
  411. its requirements, including the requirement of complete, corresponding source
  412. code\footnote{Copyleft communities' use of the term ``strong copyleft'' is
  413. undoubtedly imprecise. For example, most will call the GNU GPL a ``strong
  414. copyleft'' license, even though the GPL itself has various exceptions, such
  415. as the \hyperref[GPLv3-system-library-exception]{GPLv3's system library
  416. exception} written into the text of the license itself. Furthermore, the
  417. copyleft community continues to debate where the a license cross the line
  418. from ``strong copyleft'' to ``license that fails to respect software
  419. freedom'', although ultimately these debates are actually regarding whether
  420. the license fits \hyperref[Free Software Definition]{Free Software
  421. definition} at all.}. Thus, copyleft licenses, particularly strong ones,
  422. seek to ensure the same license covers every version of ``work based on the
  423. work'', as recognized by local copyright law, and thereby achieve the
  424. specific strategic policy aim of ensuring software freedom for all users,
  425. developers, authors, and readers who encounter the copylefted work.
  426. \subsection{Software and Non-Copyright Legal Regimes}
  427. \label{software-and-non-copyright}
  428. The use, modification and distribution of software, like many endeavors,
  429. simultaneously interacts with multiple different legal regimes. As was noted
  430. early via footnotes, copyright is merely the \textit{most common way} to
  431. restrict users' rights to copy, share, modify and/or redistribute software.
  432. However, proprietary software licenses typically use every mechanism
  433. available to subjugate users. For example:
  434. \begin{itemize}
  435. \item Unfortunately, despite much effort by many in the software freedom
  436. community to end patents that read on software (i.e., patents on
  437. computational ideas), they still exist. As such, a software
  438. program might otherwise seem to be unrestricted, but a patent might read on
  439. the software and ruin everything for its users.\footnote{See
  440. \S\S~\ref{gpl-implied-patent-grant},~\ref{GPLv2s7},~\ref{GPLv3s11} for more
  441. discussion on how the patent system interacts with copyleft, and read
  442. Richard M.~Stallman's essay,
  443. \href{http://www.wired.com/opinion/2012/11/richard-stallman-software-patents/}{\textit{Let's
  444. Limit the Effect of Software Patents, Since We Can't Eliminate Them}}
  445. for more information on the problems these patents present to society.}
  446. \item Digital Restrictions Management (usually called \defn{DRM}) is often
  447. used to impose technological restrictions on users' ability to exercise
  448. software freedom that they might otherwise be granted.\footnote{See
  449. \S~\ref{GPLv3-drm} for more information on how GPL deals with this issue.}
  450. The simplest (and perhaps oldest) form of DRM, of course, is separating
  451. software source code (read by humans), from their compiled binaries (read
  452. only by computers). Furthermore,
  453. \href{http://www.law.cornell.edu/uscode/text/17/1201}{17 USC~\S1201} often
  454. prohibits users legally from circumventing some of these DRM systems.
  455. \item Most EULAs also include a contractual agreement that bind users further
  456. by forcing them to agree to a contractual, prohibitive software license
  457. before ever even using the software.
  458. \end{itemize}
  459. Thus, most proprietary software restricts users via multiple interlocking
  460. legal and technological means. Any license that truly respect the software
  461. freedom of all users must not only grant appropriate copyright permissions,
  462. but also \textit{prevent} restrictions from other legal and technological
  463. means like those listed above.
  464. \subsection{Non-USA Copyright Regimes}
  465. \label{non-usa-copyright}
  466. Generally speaking, copyright law operates similarly enough in countries that
  467. have signed the Berne Convention on Copyright, and software freedom licenses
  468. have generally taken advantage of this international standardization of
  469. copyright law. However, copyright law does differ from country to country,
  470. and commonly, software freedom licenses like the GPL must be considered under the
  471. copyright law in the jurisdiction where any licensing dispute occurs.
  472. Those who are most familiar with the USA's system of copyright often are
  473. surprised to learn that there are certain copyright controls that cannot be
  474. waived nor disclaimed. Specifically, many copyright regimes outside the USA
  475. recognize a concept of moral rights of authors. Typically, moral rights are
  476. fully compatible with respecting software freedom, as they are usually
  477. centered around controls that software freedom licenses generally respect,
  478. such as the right of an authors to require proper attribution for their work.
  479. \section{A Community of Equality}
  480. The previous section described the principles of software freedom, a brief
  481. introduction to mechanisms that typically block these freedoms, and the
  482. simplest ways that copyright holders might grant those freedoms to their
  483. users for their copyrighted works of software. The previous section also
  484. introduced the idea of \textit{copyleft}: a licensing mechanism to use
  485. copyright to not only grant software freedom to users, but also to uphold
  486. those rights against those who might seek to curtail them.
  487. Copyleft, as defined in \S~\ref{copyleft-definition}, is a general term for this
  488. mechanism. The remainder of this text will discuss details of various
  489. real-world implementations of copyleft -- most notably, the GPL\@.
  490. This discussion begins first with some general explanation of what the GPL is
  491. able to do in software development communities. After that brief discussion
  492. in this section, deeper discussion of how GPL accomplishes this in practice
  493. follows in the next chapter.
  494. Simply put, though, the GPL ultimately creates a community of equality for
  495. both business and noncommercial users.
  496. \subsection{The Noncommercial Community}
  497. A GPL'd code base becomes a center of a vibrant development and user
  498. community. Traditionally, volunteers, operating noncommercially out of
  499. keen interest or ``scratch an itch'' motivations, produce initial versions
  500. of a GPL'd system. Because of the efficient distribution channels of the
  501. Internet, any useful GPL'd system is adopted quickly by noncommercial
  502. users.
  503. Fundamentally, the early release and quick distribution of the software
  504. gives birth to a thriving noncommercial community. Users and developers
  505. begin sharing bug reports and bug fixes across a shared intellectual
  506. commons. Users can trust the developers, because they know that if the
  507. developers fail to address their needs or abandon the project, the GPL
  508. ensures that someone else has the right to pick up development.
  509. Developers know that the users cannot redistribute their software without
  510. passing along the rights granted by the GPL, so they are assured that every
  511. one of their users is treated equally.
  512. Because of the symmetry and fairness inherent in GPL'd distribution,
  513. nearly every GPL'd package in existence has a vibrant noncommercial user
  514. and developer base.
  515. \subsection{The Commercial Community}
  516. By the same token, nearly all established GPL'd software systems have a
  517. vibrant commercial community. Nearly every GPL'd system that has gained
  518. wide adoption from noncommercial users and developers eventually begins
  519. to fuel a commercial system around that software.
  520. For example, consider the Samba file server system that allows Unix-like
  521. systems (including GNU/Linux) to serve files to Microsoft Windows systems.
  522. Two graduate students originally developed Samba in their spare time and
  523. it was deployed noncommercially in academic environments.\footnote{See
  524. \href{http://turtle.ee.ncku.edu.tw/docs/samba/history}{Andrew Tridgell's
  525. ``A bit of history and a bit of fun''}} However, very
  526. soon for-profit companies discovered that the software could work for them
  527. as well, and their system administrators began to use it in place of
  528. Microsoft Windows NT file-servers. This served to lower the cost of
  529. running such servers by orders of magnitude. There was suddenly room in
  530. Windows file-server budgets to hire contractors to improve Samba. Some of
  531. the first people hired to do such work were those same two graduate
  532. students who originally developed the software.
  533. The noncommercial users, however, were not concerned when these two
  534. fellows began collecting paychecks off of their GPL'd work. They knew
  535. that because of the nature of the GPL that improvements that were
  536. distributed in the commercial environment could easily be folded back into
  537. the standard version. Companies are not permitted to proprietarize
  538. Samba, so the noncommercial users, and even other commercial users are
  539. safe in the knowledge that the software freedom ensured by the GPL will remain
  540. protected.
  541. Commercial developers also work in concert with noncommercial
  542. developers. Those two now-long-since graduated students continue to
  543. contribute to Samba altruistically, but also get paid work doing it.
  544. Priorities change when a client is in the mix, but all the code is
  545. contributed back to the standard version. Meanwhile, many other
  546. individuals have gotten involved noncommercially as developers,
  547. because they want to ``cut their teeth on Free Software,'' or because
  548. the problems interest them. When they get good at it, perhaps they
  549. will move on to another project, or perhaps they will become
  550. commercial developers of the software themselves.
  551. No party is a threat to another in the GPL software scenario because
  552. everyone is on equal ground. The GPL protects rights of the commercial
  553. and noncommercial contributors and users equally. The GPL creates trust,
  554. because it is a level playing field for all.
  555. \subsection{Law Analogy}
  556. In his introduction to Stallman's \emph{Free Software, Free Society},
  557. Lawrence Lessig draws an interesting analogy between the law and Free
  558. Software. He argues that the laws of a free society must be protected
  559. much like the GPL protects software. So that I might do true justice to
  560. Lessig's argument, I quote it verbatim:
  561. \begin{quotation}
  562. A ``free society'' is regulated by law. But there are limits that any free
  563. society places on this regulation through law: No society that kept its
  564. laws secret could ever be called free. No government that hid its
  565. regulations from the regulated could ever stand in our tradition. Law
  566. controls. But it does so justly only when visibly. And law is visible
  567. only when its terms are knowable and controllable by those it regulates,
  568. or by the agents of those it regulates (lawyers, legislatures).
  569. This condition on law extends beyond the work of a legislature. Think
  570. about the practice of law in American courts. Lawyers are hired by their
  571. clients to advance their clients' interests. Sometimes that interest is
  572. advanced through litigation. In the course of this litigation, lawyers
  573. write briefs. These briefs in turn affect opinions written by judges.
  574. These opinions decide who wins a particular case, or whether a certain law
  575. can stand consistently with a constitution.
  576. All the material in this process is free in the sense that Stallman means.
  577. Legal briefs are open and free for others to use. The arguments are
  578. transparent (which is different from saying they are good), and the
  579. reasoning can be taken without the permission of the original lawyers.
  580. The opinions they produce can be quoted in later briefs. They can be
  581. copied and integrated into another brief or opinion. The ``source code''
  582. for American law is by design, and by principle, open and free for anyone
  583. to take. And take lawyers do---for it is a measure of a great brief that
  584. it achieves its creativity through the reuse of what happened before. The
  585. source is free; creativity and an economy is built upon it.
  586. This economy of free code (and here I mean free legal code) doesn't starve
  587. lawyers. Law firms have enough incentive to produce great briefs even
  588. though the stuff they build can be taken and copied by anyone else. The
  589. lawyer is a craftsman; his or her product is public. Yet the crafting is
  590. not charity. Lawyers get paid; the public doesn't demand such work
  591. without price. Instead this economy flourishes, with later work added to
  592. the earlier.
  593. We could imagine a legal practice that was different --- briefs and
  594. arguments that were kept secret; rulings that announced a result but not
  595. the reasoning. Laws that were kept by the police but published to no one
  596. else. Regulation that operated without explaining its rule.
  597. We could imagine this society, but we could not imagine calling it
  598. ``free.'' Whether or not the incentives in such a society would be better
  599. or more efficiently allocated, such a society could not be known as free.
  600. The ideals of freedom, of life within a free society, demand more than
  601. efficient application. Instead, openness and transparency are the
  602. constraints within which a legal system gets built, not options to be
  603. added if convenient to the leaders. Life governed by software code should
  604. be no less.
  605. Code writing is not litigation. It is better, richer, more
  606. productive. But the law is an obvious instance of how creativity and
  607. incentives do not depend upon perfect control over the products
  608. created. Like jazz, or novels, or architecture, the law gets built
  609. upon the work that went before. This adding and changing is what
  610. creativity always is. And a free society is one that assures that its
  611. most important resources remain free in just this sense.\footnote{This
  612. quotation is Copyright \copyright{} 2002, Lawrence Lessig. It is
  613. licensed under the terms of
  614. \href{http://creativecommons.org/licenses/by/1.0/}{the ``Attribution
  615. License'' version 1.0} or any later version as published by Creative
  616. Commons.}
  617. \end{quotation}
  618. In essence, lawyers are paid to service the shared commons of legal
  619. infrastructure. Few citizens defend themselves in court or write their
  620. own briefs (even though they are legally permitted to do so) because
  621. everyone would prefer to have an expert do that job.
  622. The Free Software economy is a market ripe for experts. It
  623. functions similarly to other well established professional fields like the
  624. law. The GPL, in turn, serves as the legal scaffolding that permits the
  625. creation of this vibrant commercial and noncommercial Free Software
  626. economy.
  627. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  628. \chapter{A Tale of Two Copyleft Licenses}
  629. \label{tale-of-two-copylefts}
  630. While determining the proper methodology and criteria to yield an accurate
  631. count remains difficult, the GPL is generally considered one of the most
  632. widely used Free Software licenses. For most of its history --- for 16 years
  633. from June 1991 to June 2007 --- there was really only one version of the GPL,
  634. version 2.
  635. However, the GPL had both earlier versions before version 2, and, more well
  636. known, a revision to version 3.
  637. \section{Historical Motivations for the General Public License}
  638. The earliest license to grant software freedom was likely the Berkeley
  639. Software Distribution (``BSD'') license. This license is typical of what are
  640. often called lax, highly permissive licenses. Not unlike software in the
  641. public domain, these non-copyleft licenses (usually) grant software freedom
  642. to users, but they do not go to any effort to uphold that software freedom
  643. for users. The so-called ``downstream'' (those who receive the software and
  644. then build new things based on that software) can restrict the software and
  645. distribute further.
  646. The GNU's Not Unix (``GNU'') project, which Richard M.~Stallman (``RMS'')
  647. founded in 1984 to make a complete Unix-compatible operating system
  648. implementation that assured software freedom for all. However, RMS saw that
  649. using a license that gave but did not assure software freedom would be
  650. counter to the goals of the GNU Project. RMS invented ``copyleft'' as an
  651. answer to that problem, and began using various copyleft licenses for the
  652. early GNU Project programs.\footnote{RMS writes more fully about this topic in
  653. his essay entitled simply
  654. \href{http://www.gnu.org/gnu/thegnuproject.html}{\textit{The GNU Project}}.
  655. For those who want to hear the story in his own voice,
  656. \href{http://audio-video.gnu.org/audio/}{speech recordings} of his talk,
  657. \textit{The Free Software Movement and the GNU/Linux Operating System}
  658. are also widely available}
  659. \section{Proto-GPLs And Their Impact}
  660. %FIXME-LATER: bad line break:
  661. %\href{http://www.free-soft.org/gpl_history/emacs_gpl.html}{The Emacs
  662. % General Public License}
  663. The earliest copyleft licenses were specific to various GNU programs. For
  664. example, The Emacs
  665. General Public License was likely the first copyleft license ever
  666. published. Interesting to note that even this earliest copyleft license
  667. contains a version of the well-known GPL copyleft clause:
  668. \begin{quotation}
  669. You may modify your copy or copies of GNU Emacs \ldots provided that you also
  670. \ldots cause the whole of any work that you distribute or publish, that in
  671. whole or in part contains or is a derivative of GNU Emacs or any part
  672. thereof, to be licensed at no charge to all third parties on terms identical
  673. to those contained in this License Agreement.
  674. \end{quotation}
  675. This simply stated clause is the fundamental innovation of copyleft.
  676. Specifically, copyleft \textit{uses} the copyright holders' controls on
  677. permission to modify the work to add a conditional requirement. Namely,
  678. downstream users may only have permission to modify the work if they pass
  679. along the same permissions on the modified version that came originally to
  680. them.
  681. These original program-specific proto-GPLs give an interesting window into
  682. the central ideas and development of copyleft. In particular, reviewing them
  683. shows how the text of the GPL we know has evolved to address more of the
  684. issues discussed earlier in \S~\ref{software-and-non-copyright}.
  685. \section{The GNU General Public License, Version 1}
  686. \label{GPLv1}
  687. In January 1989, the FSF announced that the GPL had been converted into a
  688. ``subroutine'' that could be reused not just for all FSF-copyrighted
  689. programs, but also by anyone else. As the FSF claimed in its announcement of
  690. the GPLv1:\footnote{The announcement of GPLv1 was published in the
  691. \href{http://www.gnu.org/bulletins/bull6.html\#SEC8}{GNU's Bulletin, vol 1,
  692. number 6 dated January 1989}. (Thanks very much to Andy Tai for his
  693. \href{http://www.free-soft.org/gpl_history/}{consolidation of research on
  694. the history of the pre-v1 GPL's}.)}
  695. \begin{quotation}
  696. To make it easier to copyleft programs, we have been improving on the
  697. legalbol architecture of the General Public License to produce a new version
  698. that serves as a general-purpose subroutine: it can apply to any program
  699. without modification, no matter who is publishing it.
  700. \end{quotation}
  701. This, like many inventive ideas, seems somewhat obvious in retrospect. But,
  702. the FSF had some bright people and access to good lawyers when it started.
  703. It took almost five years from the first copyleft licenses to get to a
  704. generalized, reusable GPLv1. In the context and mindset of the 1980s, this
  705. is not surprising. The idea of reusable licensing infrastructure was not
  706. only uncommon, it was virtually nonexistent! Even the early BSD licenses
  707. were simply copied and rewritten slightly for each new use.\footnote{It
  708. remains an interesting accident of history that the early BSD problematic
  709. ``advertising clause'' (discussion of which is somewhat beyond the scope of
  710. this tutorial) lives on into current day, simply because while the
  711. University of California at Berkeley gave unilateral permission to remove
  712. the clause from \textit{its} copyrighted works, others who adapted the BSD
  713. license with their own names in place of UC-Berkeley's never have.} The
  714. GPLv1's innovation of reusable licensing infrastructure, an obvious fact
  715. today, was indeed a novel invention for its day.\footnote{We're all just
  716. grateful that the FSF also opposes business method patents, since the FSF's
  717. patent on a ``method for reusable licensing infrastructure'' would have
  718. not expired until 2006!}
  719. \section{The GNU General Public License, Version 2}
  720. The GPLv2 was released two and a half years after GPLv1, and over the
  721. following sixteen years, it became the standard for copyleft licensing until
  722. the release of GPLv3 in 2007 (discussed in more detail in the next section).
  723. While this tutorial does not discuss the terms of GPLv1 in detail, it is
  724. worth noting below the three key changes that GPLv2 brought:
  725. \begin{itemize}
  726. \item Software patents and their danger are explicitly mentioned, inspiring
  727. (in part) the addition of GPLv2~\S\S5--7. (These sections are discussed in
  728. detail in \S~\ref{GPLv2s5}, \S~\ref{GPLv2s6} and \S~\ref{GPLv2s7} of this
  729. tutorial.)
  730. \item GPLv2~\S2's copyleft terms are expanded to more explicitly discuss the
  731. issue of combined works. (GPLv2~\S2 is discussed in detail in
  732. \S~\ref{GPLv2s2} in this tutorial).
  733. \item GPLv2~\S3 includes more detailed requirements, including the phrase
  734. ``the scripts used to control compilation and installation of the
  735. executable'', which is a central component of current GPLv2 enforcement.
  736. (GPLv2~\S3 is discussed in detail in
  737. \S~\ref{GPLv2s3} in this tutorial).
  738. \end{itemize}
  739. The next chapter discusses GPLv2 in full detail, and readers who wish to dive
  740. into the section-by-section discussion of the GPL should jump ahead now to
  741. that chapter. However, the most interesting fact to note here is how GPLv2
  742. was published with little fanfare and limited commentary. This contrasts
  743. greatly with the creation of GPLv3.
  744. \section{The GNU General Public License, Version 3}
  745. RMS began drafting GPLv2.2 in mid-2002, and FSF ran a few discussion groups
  746. during that era about new text of that license. However, rampant violations
  747. of the GPL required more immediate attention of FSF's licensing staff, and as
  748. such, much of the early 2000's was spent doing GPL enforcement
  749. work.\footnote{More on GPL enforcement is discussed in \tutorialpartsplit{a
  750. companion tutorial, \textit{A Practical Guide to GPL
  751. Compliance}}{Part~\ref{gpl-compliance-guide} of this tutorial}.} In
  752. 2006, FSF began in earnest drafting work for GPLv3.
  753. The GPLv3 process began in earnest in January 2006. It became clear that
  754. many provisions of the GPL could benefit from modification to fit new
  755. circumstances and to reflect what the entire community learned from
  756. experience with version 2. Given the scale of revision it seems proper to
  757. approach the work through public discussion in a transparent and accessible
  758. manner.
  759. The GPLv3 process continued through June 2007, culminating in publication of
  760. GPLv3 and LGPLv3 on 29 June 2007, AGPLv3 on 19 November 2007, and the GCC
  761. Runtime Library Exception on 27 January 2009.
  762. All told, four discussion drafts of GPLv3, two discussion drafts of LGPLv3
  763. and two discussion drafts of AGPLv3 were published and discussed.
  764. Ultimately, FSF remained the final arbiter and publisher of the licenses, and
  765. RMS himself their primary author, but input was sought from many parties, and
  766. these licenses do admittedly look and read more like legislation as a result.
  767. Nevertheless, all of the ``v3'' group are substantially better and improved
  768. licenses.
  769. GPLv3 and its terms are discussed in detail in Chapter~\ref{GPLv3}.
  770. \section{The Innovation of Optional ``Or Any Later'' Version}
  771. An interesting fact of all GPL licenses is that there are ultimately multiple
  772. choices for use of the license. The FSF is the primary steward of GPL (as
  773. discussed later in \S~\ref{GPLv2s9} and \S~\ref{GPLv3s14}). However, those
  774. who wish to license works under GPL are not required to automatically accept
  775. changes made by the FSF for their own copyrighted works.
  776. Each licensor may chose three different methods of licensing, as follows:
  777. \begin{itemize}
  778. \item explicitly name a single version of GPL for their work (usually
  779. indicated in shorthand by saying the license is ``GPLv$X$-only''), or
  780. \item name no version of the GPL, thus they allow their downstream recipients
  781. to select any version of the GPL they choose (usually indicated in shorthand
  782. by saying the license is simply ``GPL''), or
  783. \item name a specific version of GPL and give downstream recipients the
  784. option to choose that version ``or any later version as published by the
  785. FSF'' (usually indicated by saying the license is
  786. ``GPLv$X$-or-later'')\footnote{The shorthand of ``GPL$X+$'' is also popular
  787. for this situation. The authors of this tutorial prefer ``-or-later''
  788. syntax, because it (a) mirrors the words ``or'' and ``later from the
  789. licensing statement, (b) the $X+$ doesn't make it abundantly clear that
  790. $X$ is clearly included as a license option and (c) the $+$ symbol has
  791. other uses in computing (such as with regular expressions) that mean
  792. something different.}
  793. \end{itemize}
  794. \label{license-compatibility-first-mentioned}
  795. Oddly, this flexibility has received (in the opinion of the authors, undue)
  796. criticism, primarily because of the complex and oft-debated notion of
  797. ``license compatibility'' (which is explained in detail in
  798. \S~\ref{license-compatibility}). Copyleft licenses are generally
  799. incompatible with each other, because the details of how they implement
  800. copyleft differs. Specifically, copyleft works only because of its
  801. requirement that downstream licensors use the \textit{same} license for
  802. combined and modified works. As such, software licensed under the terms of
  803. ``GPLv2-only'' cannot be combined with works licensed ``GPLv3-or-later''.
  804. This is admittedly a frustrating outcome.
  805. Other copyleft licenses that appeared after GPL, such as the Creative Commons
  806. ``Attribution-Share Alike'' licenses, the Eclipse Public License and the
  807. Mozilla Public License \textbf{require} all copyright holders choosing
  808. to use any version of those licenses to automatically allow use of their
  809. copyrighted works under new versions.\footnote{CC-BY-SA-2.0 and greater only
  810. permit licensing of adaptations under future versions; 1.0 did not have
  811. any accomodation for future version compatibility.} Of course, Creative
  812. Commons, the Eclipse Foundation, and the Mozilla Foundation (like the FSF)
  813. have generally served as excellent stewards of their licenses. Copyright
  814. holders using those licenses seems to find it acceptable to fully delegate
  815. all future licensing decisions for their copyrights to these organizations
  816. without a second thought.
  817. However, note that FSF gives herein the control of copyright holders to
  818. decide whether or not to implicitly trust the FSF in its work of drafting
  819. future GPL versions. The FSF, for its part, does encourage copyright holders
  820. to chose by default ``GPLv$X$-or-later'' (where $X$ is the most recent
  821. version of the GPL published by the FSF). However, the FSF \textbf{does not
  822. mandate} that a choice to use any GPL requires a copyright holder ceding
  823. its authority for future licensing decisions to the FSF. In fact, the FSF
  824. considered this possibility for GPLv3 and chose not to do so, instead opting
  825. for the third-party steward designation clause discussed in
  826. Section~\ref{GPLv3s14}.
  827. \section{Complexities of Two Simultaneously Popular Copylefts}
  828. Obviously most GPL advocates would prefer widespread migration to GPLv3, and
  829. many newly formed projects who seek a copyleft license tend to choose a
  830. GPLv3-based license. However, many existing copylefted projects continue
  831. with GPLv2-only or GPLv2-or-later as their default license.
  832. While GPLv3 introduces many improvements --- many of which were designed to
  833. increase adoption by for-profit companies --- GPLv2 remains a widely used and
  834. extremely popular license. The GPLv2 is, no doubt, a good and useful
  835. license.
  836. However, unlike GPLv1 before it,
  837. GPLv2 remains an integral part of the copyleft licensing infrastructure. As such, those who seek to have expertise in current
  838. topics of copyleft licensing need to study both the GPLv2 and GPLv3 family of
  839. licenses.
  840. Furthermore, GPLv3 is more easily understood by first studying GPLv2.
  841. This is not only because of their chronological order, but also because much
  842. of the discussion material available for GPLv3 tends to talk about GPLv3 in
  843. contrast to GPLv2. As such, a strong understanding of GPLv2 helps in
  844. understanding most of the third-party material found regarding GPLv3. Thus,
  845. the following chapter begins a deep discussion of GPLv2.
  846. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  847. \chapter{Running Software and Verbatim Copying}
  848. \label{run-and-verbatim}
  849. This chapter begins the deep discussion of the details of the terms of
  850. GPLv2\@. In this chapter, we consider the first two sections: GPLv2 \S\S
  851. 0--2. These are the straightforward sections of the GPL that define the
  852. simplest rights that the user receives.
  853. \section{GPLv2~\S0: Freedom to Run}
  854. \label{GPLv2s0}
  855. GPLv2~\S0, the opening section of GPLv2, sets forth that copyright law governs
  856. the work. It specifically points out that it is the ``copyright
  857. holder'' who decides if a work is licensed under its terms and explains
  858. how the copyright holder might indicate this fact.
  859. A bit more subtly, GPLv2~\S0 makes an inference that copyright law is the only
  860. system that can restrict the software. Specifically, it states:
  861. \begin{quote}
  862. Activities other than copying, distribution and modification are not
  863. covered by this License; they are outside its scope.
  864. \end{quote}
  865. In essence, the license governs \emph{only} those activities, and all other
  866. activities are unrestricted, provided that no other agreements trump GPLv2
  867. (which they cannot; see Sections~\ref{GPLv2s6} and~\ref{GPLv2s7}). This is
  868. very important, because the Free Software community heavily supports
  869. users' rights to ``fair use'' and ``unregulated use'' of copyrighted
  870. material. GPLv2 asserts through this clause that it supports users' rights
  871. to fair and unregulated uses.
  872. Fair use (called ``fair dealing'' in some jurisdictions) of copyrighted
  873. material is an established legal doctrine that permits certain activities
  874. regardless of whether copyright law would otherwise restrict those activities.
  875. Discussion of the various types of fair use activity are beyond the scope of
  876. this tutorial. However, one important example of fair use is the right to
  877. quote portions of the text in a larger work so as to criticize or suggest
  878. changes. This fair use right is commonly used on mailing lists when
  879. discussing potential improvements or changes to Free Software.
  880. Fair use is a doctrine established by the courts or by statute. By
  881. contrast, unregulated uses are those that are not covered by the statue
  882. nor determined by a court to be covered, but are common and enjoyed by
  883. many users. An example of unregulated use is reading a printout of the
  884. program's source code like an instruction book for the purpose of learning
  885. how to be a better programmer. The right to read something that you have
  886. access to is and should remain unregulated and unrestricted.
  887. \medskip
  888. Thus, the GPLv2 protects users' fair and unregulated use rights precisely by
  889. not attempting to cover them. Furthermore, the GPLv2 ensures the freedom
  890. to run specifically by stating the following:
  891. \begin{quote}
  892. ''The act of running the Program is not restricted.''
  893. \end{quote}
  894. Thus, users are explicitly given the freedom to run by GPLv2~\S0.
  895. \medskip
  896. The bulk of GPLv2~\S0 not yet discussed gives definitions for other terms used
  897. throughout. The only one worth discussing in detail is ``work based on
  898. the Program''. The reason this definition is particularly interesting is
  899. not for the definition itself, which is rather straightforward, but
  900. because it clears up a common misconception about the GPL\@.
  901. The GPL is often mistakenly criticized because it fails to give a
  902. definition of ``derivative work'' or ``combined work''. In fact, it would be incorrect and
  903. problematic if the GPL attempted to define these terms. A copyright license, in
  904. fact, has no control over the rules of copyright themselves. Such rules are
  905. the domain of copyright law and the courts --- not the licenses that utilize
  906. those systems.
  907. Copyright law as a whole does not propose clear and straightforward guidelines
  908. for identifying the derivative and/or combined works of software. However,
  909. no copyright license --- not even the GNU GPL --- can be blamed for this.
  910. Legislators and court opinions must give us guidance in borderline cases.
  911. Meanwhile, lawyers will likely based their conclusions on the application of rules
  912. made in the context of literary or artistic copyright to the different
  913. context of computer programming and by analyzing the (somewhat limited) case
  914. law and guidance available from various sources.
  915. (Chapter~\ref{derivative-works} discusses this issue in depth.)
  916. \section{GPLv2~\S1: Verbatim Copying}
  917. \label{GPLv2s1}
  918. GPLv2~\S1 covers the matter of redistributing the source code of a program
  919. exactly as it was received. This section is quite straightforward.
  920. However, there are a few details worth noting here.
  921. The phrase ``in any medium'' is important. This, for example, gives the
  922. freedom to publish a book that is the printed copy of the program's source
  923. code. It also allows for changes in the medium of distribution. Some
  924. vendors may ship Free Software on a CD, but others may place it right on
  925. the hard drive of a pre-installed computer. Any such redistribution media
  926. is allowed.
  927. Preservation of copyright notice and license notifications are mentioned
  928. specifically in GPLv2~\S1. These are in some ways the most important part of
  929. the redistribution, which is why they are mentioned by name. GPL
  930. always strives to make it abundantly clear to anyone who receives the
  931. software what its license is. The goal is to make sure users know their
  932. rights and freedoms under GPL, and to leave no reason that users might be
  933. surprised the software is GPL'd. Thus
  934. throughout the GPL, there are specific references to the importance of
  935. notifying others down the distribution chain that they have rights under
  936. GPL.
  937. GPL disclaims all warranties that legally can be disclaimed (which is
  938. discussed later in sections~\ref{GPLv2s11} and~\ref{GPLv2s12}). Users
  939. generally rarely expect their software comes with any warranties, since
  940. typically all EULAs and other Free Software licenses disclaim warranties too.
  941. However, since many local laws require ``consipicous'' warranty disclaimers,
  942. GPLv2~\S1 explicitly mentions the importance of keeping warranty disclaimers
  943. in tact upon redistribution.
  944. Note finally that GPLv2~\S1 creates groundwork for the important defense of
  945. commercial freedom. GPLv2~\S1 clearly states that in the case of verbatim
  946. copies, one may make money. Re-distributors are fully permitted to charge
  947. for the re-distribution of copies of Free Software. In addition, they may
  948. provide the warranty protection that the GPL disclaims as an additional
  949. service for a fee. (See Section~\ref{Business Models} for more discussion
  950. on making a profit from Free Software redistribution.)
  951. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  952. \chapter{Derivative Works: Statute and Case Law}
  953. \label{derivative-works}
  954. As described in the \hyperref[copyleft-definition]{earlier general discussion
  955. of copyleft}, strong copyleft licenses such as the GPL seek to uphold
  956. software freedom via the copyright system. This principle often causes
  957. theoretical or speculative dispute among lawyers, because ``the work'' ---
  958. the primary unit of consideration under most copyright rules -- is not a unit
  959. of computer programming. In order to determine whether a ``routine'' an
  960. ``object'', a ``function'', a ``library'' or any other unit of software is
  961. part of one ``work'' when combined with other GPL'd code, we must ask a
  962. question that copyright law will not directly answer in the same technical
  963. terms.
  964. Therefore, this chapter digresses from discussion of GPL's exact text to
  965. consider the matter of combined and/or derivative works --- a concept that we must
  966. understand fully before considering GPLv2~\S\S2--3\@. At least under USA
  967. copyright law, The GPL, and Free
  968. Software licensing in general, relies critically on the concept of
  969. ``derivative work'' since software that is ``independent,'' (i.e., not
  970. ``derivative'') of Free Software need not abide by the terms of the
  971. applicable Free Software license. As much is required by \S~106 of the
  972. Copyright Act, 17 U.S.C. \S~106 (2002), and admitted by Free Software
  973. licenses, such as the GPL, which (as we have seen) states in GPLv2~\S0 that ``a
  974. `work based on the Program' means either the Program or any derivative
  975. work under copyright law.'' It is being a derivative work of Free Software
  976. that triggers the necessity to comply with the terms of the Free Software
  977. license under which the original work is distributed. Therefore, one is
  978. left to ask, just what is a ``derivative work''? The answer to that
  979. question differs depending on which court is being asked.
  980. The analysis in this chapter sets forth the differing definitions of
  981. derivative work by the circuit courts. The broadest and most
  982. established definition of derivative work for software is the
  983. abstraction, filtration, and comparison test (``the AFC test'') as
  984. created and developed by the Second Circuit. Some circuits, including
  985. the Ninth Circuit and the First Circuit, have either adopted narrower
  986. versions of the AFC test or have expressly rejected the AFC test in
  987. favor of a narrower standard. Further, several other circuits have yet
  988. to adopt any definition of derivative work for software.
  989. As an introductory matter, it is important to note that literal copying of
  990. a significant portion of source code is not always sufficient to establish
  991. that a second work is a derivative work of an original
  992. program. Conversely, a second work can be a derivative work of an original
  993. program even though absolutely no copying of the literal source code of
  994. the original program has been made. This is the case because copyright
  995. protection does not always extend to all portions of a program's code,
  996. while, at the same time, it can extend beyond the literal code of a
  997. program to its non-literal aspects, such as its architecture, structure,
  998. sequence, organization, operational modules, and computer-user interface.
  999. \section{The Copyright Act}
  1000. The copyright act is of little, if any, help in determining the definition
  1001. of a derivative work of software. However, the applicable provisions do
  1002. provide some, albeit quite cursory, guidance. Section 101 of the Copyright
  1003. Act sets forth the following definitions:
  1004. \begin{quotation}
  1005. A ``computer program'' is a set of statements or instructions to be used
  1006. directly or indirectly in a computer in order to bring about a certain
  1007. result.
  1008. A ``derivative work'' is a work based upon one or more preexisting works,
  1009. such as a translation, musical arrangement, dramatization,
  1010. fictionalization, motion picture version, sound recording, art
  1011. reproduction, abridgment, condensation, or any other form in which a work
  1012. may be recast, transformed, or adapted. A work consisting of editorial
  1013. revisions, annotations, elaborations, or other modifications which, as a
  1014. whole, represent an original work of authorship, is a ``derivative work.''
  1015. \end{quotation}
  1016. These are the only provisions in the Copyright Act relevant to the
  1017. determination of what constitutes a derivative work of a computer
  1018. program. Another provision of the Copyright Act that is also relevant to
  1019. the definition of derivative work is \S~102(b), which reads as follows:
  1020. \begin{quotation}
  1021. In no case does copyright protection for an original work of authorship
  1022. extend to any idea, procedure, process, system, method of operation,
  1023. concept, principle, or discovery, regardless of the form in which it is
  1024. described, explained, illustrated, or embodied in such work.
  1025. \end{quotation}
  1026. Therefore, before a court can ask whether one program is a derivative work
  1027. of another program, it must be careful not to extend copyright protection
  1028. to any ideas, procedures, processes, systems, methods of operation,
  1029. concepts, principles, or discoveries contained in the original program. It
  1030. is the implementation of this requirement to ``strip out'' unprotectable
  1031. elements that serves as the most frequent issue over which courts
  1032. disagree.
  1033. \section{Abstraction, Filtration, Comparison Test}
  1034. As mentioned above, the AFC test for determining whether a computer
  1035. program is a derivative work of an earlier program was created by the
  1036. Second Circuit and has since been adopted in the Fifth, Tenth, and
  1037. Eleventh Circuits. Computer Associates Intl., Inc. v. Altai, Inc., 982
  1038. F.2d 693 (2nd Cir. 1992); Engineering Dynamics, Inc. v. Structural
  1039. Software, Inc., 26 F.3d 1335 (5th Cir. 1994); Kepner-Tregoe,
  1040. Inc. v. Leadership Software, Inc., 12 F.3d 527 (5th Cir. 1994); Gates
  1041. Rubber Co. v. Bando Chem. Indust., Ltd., 9 F.3d 823 (10th Cir. 1993);
  1042. Mitel, Inc. v. Iqtel, Inc., 124 F.3d 1366 (10th Cir. 1997); Bateman
  1043. v. Mnemonics, Inc., 79 F.3d 1532 (11th Cir. 1996); and, Mitek Holdings,
  1044. Inc. v. Arce Engineering Co., Inc., 89 F.3d 1548 (11th Cir. 1996).
  1045. Under the AFC test, a court first abstracts from the original program its
  1046. constituent structural parts. Then, the court filters from those
  1047. structural parts all unprotectable portions, including incorporated ideas,
  1048. expression that is necessarily incidental to those ideas, and elements
  1049. that are taken from the public domain. Finally, the court compares any and
  1050. all remaining kernels of creative expression to the structure of the
  1051. second program to determine whether the software programs at issue are
  1052. substantially similar so as to warrant a finding that one is the
  1053. derivative work of the other.
  1054. Often, the courts that apply the AFC test will perform a quick initial
  1055. comparison between the entirety of the two programs at issue in order to
  1056. help determine whether one is a derivative work of the other. Such a
  1057. holistic comparison, although not a substitute for the full application of
  1058. the AFC test, sometimes reveals a pattern of copying that is not otherwise
  1059. obvious from the application of the AFC test when, as discussed below,
  1060. only certain components of the original program are compared to the second
  1061. program. If such a pattern is revealed by the quick initial comparison,
  1062. the court is more likely to conclude that the second work is indeed a
  1063. derivative of the original.
  1064. \subsection{Abstraction}
  1065. The first step courts perform under the AFC test is separation of the
  1066. work's ideas from its expression. In a process akin to reverse
  1067. engineering, the courts dissect the original program to isolate each level
  1068. of abstraction contained within it. Courts have stated that the
  1069. abstractions step is particularly well suited for computer programs
  1070. because it breaks down software in a way that mirrors the way it is
  1071. typically created. However, the courts have also indicated that this step
  1072. of the AFC test requires substantial guidance from experts, because it is
  1073. extremely fact and situation specific.
  1074. By way of example, one set of abstraction levels is, in descending order
  1075. of generality, as follows: the main purpose, system architecture, abstract
  1076. data types, algorithms and data structures, source code, and object
  1077. code. As this set of abstraction levels shows, during the abstraction step
  1078. of the AFC test, the literal elements of the computer program, namely the
  1079. source and object code, are defined as particular levels of
  1080. abstraction. Further, the source and object code elements of a program are
  1081. not the only elements capable of forming the basis for a finding that a
  1082. second work is a derivative of the program. In some cases, in order to
  1083. avoid a lengthy factual inquiry by the court, the owner of the copyright in
  1084. the original work will submit its own list of what it believes to be the
  1085. protected elements of the original program. In those situations, the court
  1086. will forgo performing its own abstraction, and proceed to the second step of
  1087. the AFC test.
  1088. \subsection{Filtration}
  1089. The most difficult and controversial part of the AFC test is the second
  1090. step, which entails the filtration of protectable expression contained in
  1091. the original program from any unprotectable elements nestled therein. In
  1092. determining which elements of a program are unprotectable, courts employ a
  1093. myriad of rules and procedures to sift from a program all the portions
  1094. that are not eligible for copyright protection.
  1095. First, as set forth in \S~102(b) of the Copyright Act, any and all ideas
  1096. embodied in the program are to be denied copyright protection. However,
  1097. implementing this rule is not as easy as it first appears. The courts
  1098. readily recognize the intrinsic difficulty in distinguishing between ideas
  1099. and expression and that, given the varying nature of computer programs,
  1100. doing so will be done on an ad hoc basis. The first step of the AFC test,
  1101. the abstraction, exists precisely to assist in this endeavor by helping
  1102. the court separate out all the individual elements of the program so that
  1103. they can be independently analyzed for their expressive nature.
  1104. A second rule applied by the courts in performing the filtration step of
  1105. the AFC test is the doctrine of merger, which denies copyright protection
  1106. to expression necessarily incidental to the idea being expressed. The
  1107. reasoning behind this doctrine is that when there is only one way to
  1108. express an idea, the idea and the expression merge, meaning that the
  1109. expression cannot receive copyright protection due to the bar on copyright
  1110. protection extending to ideas. In applying this doctrine, a court will ask
  1111. whether the program's use of particular code or structure is necessary for
  1112. the efficient implementation of a certain function or process. If so, then
  1113. that particular code or structure is not protected by copyright and, as a
  1114. result, it is filtered away from the remaining protectable expression.
  1115. A third rule applied by the courts in performing the filtration step of
  1116. the AFC test is the doctrine of scenes a faire, which denies copyright
  1117. protection to elements of a computer program that are dictated by external
  1118. factors. Such external factors can include:
  1119. \begin{itemize}
  1120. \item The mechanical
  1121. specifications of the computer on which a particular program is intended
  1122. to operate
  1123. \item Compatibility requirements of other programs with which a
  1124. program is designed to operate in conjunction
  1125. \item Computer manufacturers'
  1126. design standards
  1127. \item Demands of the industry being serviced, and widely accepted programming practices within the computer industry
  1128. \end{itemize}
  1129. Any code or structure of a program that was shaped predominantly in
  1130. response to these factors is filtered out and not protected by
  1131. copyright. Lastly, elements of a computer program are also to be filtered
  1132. out if they were taken from the public domain or fail to have sufficient
  1133. originality to merit copyright protection.
  1134. Portions of the source or object code of a computer program are rarely
  1135. filtered out as unprotectable elements. However, some distinct parts of
  1136. source and object code have been found unprotectable. For example,
  1137. constants, the invariable integers comprising part of formulas used to
  1138. perform calculations in a program, are unprotectable. Further, although
  1139. common errors found in two programs can provide strong evidence of
  1140. copying, they are not afforded any copyright protection over and above the
  1141. protection given to the expression containing them.
  1142. \subsection{Comparison}
  1143. The third and final step of the AFC test entails a comparison of the
  1144. original program's remaining protectable expression to a second
  1145. program. The issue will be whether any of the protected expression is
  1146. copied in the second program and, if so, what relative importance the
  1147. copied portion has with respect to the original program overall. The
  1148. ultimate inquiry is whether there is ``substantial'' similarity between
  1149. the protected elements of the original program and the potentially
  1150. derivative work. The courts admit that this process is primarily
  1151. qualitative rather than quantitative and is performed on a case-by-case
  1152. basis. In essence, the comparison is an ad hoc determination of whether
  1153. the protectable elements of the original program that are contained in the
  1154. second work are significant or important parts of the original program. If
  1155. so, then the second work is a derivative work of the first. If, however,
  1156. the amount of protectable elements copied in the second work are so small
  1157. as to be de minimis, then the second work is not a derivative work of the
  1158. original.
  1159. \section{Analytic Dissection Test}
  1160. The Ninth Circuit has adopted the analytic dissection test to determine
  1161. whether one program is a derivative work of another. Apple Computer,
  1162. Inc. v. Microsoft Corp., 35 F.3d 1435 (9th Cir. 1994). The analytic
  1163. dissection test first considers whether there are substantial similarities
  1164. in both the ideas and expressions of the two works at issue. Once the
  1165. similar features are identified, analytic dissection is used to determine
  1166. whether any of those similar features are protected by copyright. This
  1167. step is the same as the filtration step in the AFC test. After identifying
  1168. the copyrightable similar features of the works, the court then decides
  1169. whether those features are entitled to ``broad'' or ``thin''
  1170. protection. ``Thin'' protection is given to non-copyrightable facts or
  1171. ideas that are combined in a way that affords copyright protection only
  1172. from their alignment and presentation, while ``broad'' protection is given
  1173. to copyrightable expression itself. Depending on the degree of protection
  1174. afforded, the court then sets the appropriate standard for a subjective
  1175. comparison of the works to determine whether, as a whole, they are
  1176. sufficiently similar to support a finding that one is a derivative work of
  1177. the other. ``Thin'' protection requires the second work be virtually
  1178. identical in order to be held a derivative work of an original, while
  1179. ``broad'' protection requires only a ``substantial similarity.''
  1180. \section{No Protection for ``Methods of Operation''}
  1181. The First Circuit has taken the position that the AFC test is inapplicable
  1182. when the works in question relate to unprotectable elements set forth in
  1183. \S~102(b). Their approach results in a much narrower definition
  1184. of derivative work for software in comparison to other circuits. Specifically,
  1185. the
  1186. First Circuit holds that ``method of operation,'' as used in \S~102(b) of
  1187. the Copyright Act, refers to the means by which users operate
  1188. computers. Lotus Development Corp. v. Borland Int'l., Inc., 49 F.3d 807
  1189. (1st Cir. 1995). In Lotus, the court held that a menu command
  1190. hierarchy for a computer program was uncopyrightable because it did not
  1191. merely explain and present the program's functional capabilities to the
  1192. user, but also served as a method by which the program was operated and
  1193. controlled. As a result, under the First Circuit's test, literal copying
  1194. of a menu command hierarchy, or any other ``method of operation,'' cannot
  1195. form the basis for a determination that one work is a derivative of
  1196. another. As a result, courts in the First Circuit that apply the AFC test
  1197. do so only after applying a broad interpretation of \S~102(b) to filter out
  1198. unprotected elements. E.g., Real View, LLC v. 20-20 Technologies, Inc.,
  1199. 683 F. Supp.2d 147, 154 (D. Mass. 2010).
  1200. \section{No Test Yet Adopted}
  1201. Several circuits, most notably the Fourth and Seventh, have yet to
  1202. declare their definition of derivative work and whether or not the
  1203. AFC, Analytic Dissection, or some other test best fits their
  1204. interpretation of copyright law. Therefore, uncertainty exists with
  1205. respect to determining the extent to which a software program is a
  1206. derivative work of another in those circuits. However, one may presume
  1207. that they would give deference to the AFC test since it is by far the
  1208. majority rule among those circuits that have a standard for defining
  1209. a software derivative work.
  1210. \section{Cases Applying Software Derivative Work Analysis}
  1211. In the preeminent case regarding the definition of a derivative work for
  1212. software, Computer Associates v. Altai, the plaintiff alleged that its
  1213. program, Adapter, which was used to handle the differences in operating
  1214. system calls and services, was infringed by the defendant's competitive
  1215. program, Oscar. About 30\% of Oscar was literally the same code as
  1216. that in Adapter. After the suit began, the defendant rewrote those
  1217. portions of Oscar that contained Adapter code in order to produce a new
  1218. version of Oscar that was functionally competitive with Adapter, without
  1219. having any literal copies of its code. Feeling slighted still, the
  1220. plaintiff alleged that even the second version of Oscar, despite having no
  1221. literally copied code, also infringed its copyrights. In addressing that
  1222. question, the Second Circuit promulgated the AFC test.
  1223. In abstracting the various levels of the program, the court noted a
  1224. similarity between the two programs' parameter lists and macros. However,
  1225. following the filtration step of the AFC test, only a handful of the lists
  1226. and macros were protectable under copyright law because they were either
  1227. in the public domain or required by functional demands on the
  1228. program. With respect to the handful of parameter lists and macros that
  1229. did qualify for copyright protection, after performing the comparison step
  1230. of the AFC test, it was reasonable for the district court to conclude that
  1231. they did not warrant a finding of infringement given their relatively minor
  1232. contribution to the program as a whole. Likewise, the similarity between
  1233. the organizational charts of the two programs was not substantial enough
  1234. to support a finding of infringement because they were too simple and
  1235. obvious to contain any original expression.
  1236. In the case of Oracle America v. Google, 872 F. Supp.2d 974 (N.D. Cal. 2012),
  1237. the Northern District of California District Court examined the question of
  1238. whether the application program interfaces (APIs) associated with the Java
  1239. programming language are entitled to copyright protection. While the
  1240. court expressly declined to rule whether all APIs are free to use without
  1241. license (872 F. Supp.2d 974 at 1002), the court held that the command
  1242. structure and taxonomy of the APIs were not protectable under copyright law.
  1243. Specifically, the court characterized the command structure and taxonomy as
  1244. both a ``method of operation'' (using an approach not dissimilar to the
  1245. First Circuit's analysis in Lotus) and a ``functional requirement for
  1246. compatibility'' (using Sega v. Accolade, 977 F.2d 1510 (9th Cir. 1992) and
  1247. Sony Computer Ent. v. Connectix, 203 F.3d 596 (9th Cir. 2000) as analogies),
  1248. and thus unprotectable subject matter under \S~102(b).
  1249. Perhaps not surprisingly, there have been few other cases involving a highly
  1250. detailed software derivative work analysis. Most often, cases involve
  1251. clearer basis for decision, including frequent bad faith on the part of
  1252. the defendant or over-aggressiveness on the part of the plaintiff.
  1253. \section{How Much Do Derivative Works Matter?}
  1254. It is certainly true that GPL intends for any work that is determined a
  1255. ``derivative work'' under copyright law must be licensed as a whole under
  1256. GPL\@, as will be discussed in the following chapter. However, as we finish
  1257. up our discussion derivative works, we must note that preparation of a
  1258. derivative work is by far not the only way to create a new work covered by
  1259. GPL\@.
  1260. In fact, while derivative work preparation is perhaps the most exciting area
  1261. of legal issues to consider, the more mundane ways to create a new work
  1262. covered by GPL are much more common. For example, copyright statutes
  1263. generally require permission from the copyright holder to grant explicit
  1264. permission to modify a work in any manner. As discussed in the next chapter,
  1265. the GPL {\em does} grant such permission, but requires the modified work must
  1266. also be licensed under the terms of the GPL (and only GPL:
  1267. see\S~\ref{GPLv2s6} in this tutorial). Determining whether software was
  1268. modified is a substantially easier analysis than the derivative work
  1269. discussions and considerations in this chapter.
  1270. The question of derivative works, when and how they are made, is undoubtedly
  1271. an essential discussion in the interpretation and consideration of copyleft.
  1272. That is why this chapter was included in this tutorial. However, as we
  1273. return from this digression and resume discussion of the detailed text of the
  1274. GPLv2, we must gain a sense of perspective: most GPL questions center around
  1275. questions of modification and distribution, not preparation of derivative
  1276. works. Derivative work preparation is ultimately a small subset of the types
  1277. of modified versions of the software a developer might create, thus, while an
  1278. excessive focus on derivative works indulges us in the more exciting areas of
  1279. copyleft, we must keep a sense of perspective regarding their relative
  1280. importance.
  1281. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  1282. \chapter{Modified Source and Binary Distribution}
  1283. \label{source-and-binary}
  1284. In this chapter, we discuss the two core sections that define the rights
  1285. and obligations for those who modify, improve, and/or redistribute GPL'd
  1286. software. These sections, GPLv2~\S\S2--3, define the central core rights and
  1287. requirements of GPLv2\@.
  1288. \section{GPLv2~\S2: Share and Share Alike}
  1289. \label{GPLv2s2}
  1290. For many, this is where the ``magic'' happens that defends software
  1291. freedom upon redistribution. GPLv2~\S2 is the only place in GPLv2
  1292. that governs the modification controls of copyright law. If users
  1293. distribute modified versions a GPLv2'd program, they must follow the terms of GPLv2~\S2 in making
  1294. those changes. Thus, this sections ensures that the body of GPL'd software, as it
  1295. continues and develops, remains Free as in freedom.
  1296. To achieve that goal, GPLv2~\S2 first sets forth that the rights of
  1297. redistribution of modified versions are the same as those for verbatim
  1298. copying, as presented in GPLv2~\S1. Therefore, the details of charging money,
  1299. keeping copyright notices intact, and other GPLv2~\S1 provisions are intact
  1300. here as well. However, there are three additional requirements.
  1301. \subsection{The Simpler Parts of GPLv2~\S2}
  1302. % FIXME: GPLv2~\S2(a) isn't discussed heavily here and more should be
  1303. % discussed about it. There have been developer questions. One idea I had
  1304. % was to write up:
  1305. % http://ebb.org/bkuhn/blog/2011/03/11/linux-red-hat-gpl.html
  1306. % as a compliance case study specific to GPLv2 Section 2(a)
  1307. %
  1308. % Another point to discuss here -- or maybe it goes better in the compliance
  1309. % case study ? -- is to explain that git logs ARE adequate but possibly
  1310. % overkill.
  1311. The first (GPLv2~\S2(a)) requires that modified files carry ``prominent
  1312. notices'' explaining what changes were made and the date of such
  1313. changes. This section does not prescribe some specific way of
  1314. marking changes nor does it control the process of how changes are made.
  1315. Primarily, GPLv2~\S2(a) seeks to ensure that those receiving modified
  1316. versions know the history of changes to the software. For some users,
  1317. it is important to know that they are using the standard version of
  1318. program, because while there are many advantages to using a fork,
  1319. there are a few disadvantages. Users should be informed about the
  1320. historical context of the software version they use, so that they can
  1321. make proper support choices. Finally, GPLv2~\S2(a) serves an academic
  1322. purpose --- ensuring that future developers can use a diachronic
  1323. approach to understand the software.
  1324. GPLv2~\S2(c), a relatively simple section, requires that any program which
  1325. (before modification) ``normally reads commands interactively when run'' and
  1326. displays or prints legal information also display all copyright notices,
  1327. warranty disclaimer, modification indications and a pointer to the license,
  1328. even in modified versions. The requirement is relatively simple, and relates
  1329. to an important policy goal of copyleft: downstream users should be informed
  1330. of their rights. Its implications and details are straightforward and
  1331. simple.
  1332. \subsection{GPLv2~\S2(b)}
  1333. Meanwhile, GPLv2~\S2(b) requires careful and extensive study. Its four short lines embody
  1334. the some of the essential legal details of ``share and share alike''. These 46 words are
  1335. considered by some to be the most worthy of careful scrutiny because they
  1336. can be a source of great confusion when not properly understood.
  1337. In considering GPLv2~\S2(b), first note the qualifier: it \textit{only} applies to
  1338. derivative, combined and/or modified works that ``you distribute or publish''. Despite years of
  1339. education efforts on this matter, many still believe that modifiers
  1340. of GPL'd software \textit{must} publish or otherwise
  1341. share their changes. On the contrary, GPLv2~\S2(b) {\bf does not apply if} the
  1342. changes are never distributed. Indeed, the freedom to make private,
  1343. personal, unshared changes to software for personal use only should be
  1344. protected and defended.\footnote{Most Free Software enthusiasts believe there is a {\bf
  1345. moral} obligation to redistribute changes that are generally useful,
  1346. and they often encourage companies and individuals to do so. However, there
  1347. is a clear distinction between what one {\bf ought} to do and what one
  1348. {\bf must} do.}
  1349. Next, we again encounter the same matter that appears in GPLv2~\S0, in the
  1350. following text:
  1351. \begin{quote}
  1352. ``...that in whole or part contains or is derived from the Program or any part thereof.''
  1353. \end{quote}
  1354. Again, the GPL relies here on copyright law.
  1355. If, under copyright law, the modified version ``contains or is
  1356. derived from'' the GPL'd software, then the requirements of GPLv2~\S2(b)
  1357. apply. The GPL invokes its control as a copyright license over the
  1358. modification of the work in combination with its control over distribution
  1359. of the work.
  1360. The final clause of GPLv2~\S2(b) describes what the licensee must do if she
  1361. distributes or publishes a modified version of the work --- namely, the following:
  1362. \begin{quote}
  1363. [The work must] be licensed as a whole at no charge to all third parties
  1364. under the terms of this License.
  1365. \end{quote}
  1366. That is probably the most tightly-packed phrase in all of the GPL\@.
  1367. Consider each subpart carefully.
  1368. The work ``as a whole'' is what is to be licensed. This is an important
  1369. point that GPLv2~\S2 spends an entire paragraph explaining; thus this phrase is
  1370. worthy of a lengthy discussion here. As a programmer modifies a software
  1371. program, she generates new copyrighted material --- fixing expressions of
  1372. ideas into the tangible medium of electronic file storage. That
  1373. programmer is indeed the copyright holder of those new changes. However,
  1374. those changes are part and parcel to the original work distributed to
  1375. the programmer under GPL\@. Thus, the license of the original work
  1376. affects the license of the new whole combined and/or derivative work.
  1377. % {\cal I}
  1378. \newcommand{\gplusi}{$\mathcal{G\!\!+\!\!I}$}
  1379. \newcommand{\worki}{$\mathcal{I}$}
  1380. \newcommand{\workg}{$\mathcal{G}$}
  1381. \label{separate-and-independent}
  1382. It is certainly possible to take an existing independent work (called
  1383. \worki{}) and combine it with a GPL'd program (called \workg{}). The
  1384. license of \worki{}, when it is distributed as a separate and independent
  1385. work, remains the prerogative of the copyright holder of \worki{}.
  1386. However, when \worki{} is combined with \workg{}, it produces a new work
  1387. that is the combination of the two (called \gplusi{}). The copyright of
  1388. this combined work, \gplusi{}, is held by the original copyright
  1389. holder of each of the two works.
  1390. In this case, GPLv2~\S2 lays out the terms by which \gplusi{} may be
  1391. distributed and copied. By default, under copyright law, the copyright
  1392. holder of \worki{} would not have been permitted to distribute \gplusi{};
  1393. copyright law forbids it without the expressed permission of the copyright
  1394. holder of \workg{}. (Imagine, for a moment, if \workg{} were a proprietary
  1395. product --- would its copyright holders give you permission to create and distribute
  1396. \gplusi{} without paying them a hefty sum?) The license of \workg{}, the
  1397. GPL, states the options for the copyright holder of \worki{}
  1398. who may want to create and distribute \gplusi{}. The GPL's pre-granted
  1399. permission to create and distribute combined and/or derivative works, provided the terms
  1400. of the GPL are upheld, goes far above and beyond the permissions that one
  1401. would get with a typical work not covered by a copyleft license. Thus, to
  1402. say that this condition is any way unreasonable is simply ludicrous.
  1403. The GPL recognizes what is outside its scope. When a programmer's work is
  1404. ``separate and independent'' from any GPL'd program code with which it could be
  1405. combined, then the obligations of copyleft do not extend to the work
  1406. separately distributed. Thus, Far from attempting to extend copyleft beyond the
  1407. scope of copyright, the licenses explicitly recognize.
  1408. Thus, GPL recognizes what is outside its scope. When a programmer's work is
  1409. ``separate and independent'' from any GPL'd program code with which it could
  1410. be combined, then copyleft obligations do not extend to the independent work
  1411. separately distributed. Thus, far from attempting to extend copyleft beyond
  1412. the scope of copyright, GPL explicitly limits the scope of copyleft to the
  1413. scope of copyright.
  1414. GPL does not, however (as is sometimes suggested) distinguish ``dynamic''
  1415. from ``static'' linking of program code. It is occasionally suggested that a
  1416. subroutine ``dynamically'' linked to GPL'd code is, by virtue of the linking
  1417. alone, inherently outside the scope of copyleft on the main work. This is a
  1418. misunderstanding. When two software components are joined together to make
  1419. one work (whether a main and some library subroutines, two objects with their
  1420. respective methods, or a program and a ``plugin'') the combination infringes
  1421. the copyright on the components if the combination required copyright
  1422. permission from the component copyright holders, as such permission was
  1423. either not available or was available on terms that were not observed.
  1424. In other words, when combining other software with GPL'd components, the only
  1425. available permission is GPL\@. The combiner must observe and respect the GPL
  1426. observed on the combination as a whole. It matters not if that combination
  1427. is made with a linker before distribution of the executable, is made by the
  1428. operating system in order to share libraries for execution efficiency at
  1429. runtime, or results from runtime references in the language at runtime (as in
  1430. Java programs).
  1431. % FIXME-SOON:
  1432. % A commonly asked question is whether or not separated distribution (i.e.,
  1433. % dynamic loading of a module that is expected to be present on the
  1434. % downstream sytem) triggers the copyleft requirement. The text above
  1435. % hints at that issue, with reference to Java runtime. However, here would
  1436. % likely be the natural place to discuss that issue in more depth. I have
  1437. % never actually studied this specific question in a GPLv2 vs. GPLv3
  1438. % analysis, and as such I'd want to do that first. Furthermore, the FSF
  1439. % has not publicly opined on this question to my knowledge, so I'd want to
  1440. % see possible update to
  1441. % http://www.gnu.org/licenses/gpl-faq.html#GPLStaticVsDynamic to mention
  1442. % this issue before opining about it in the Guide.
  1443. % I'm not aware, BTW, of any dissenting opinions or disagreements among
  1444. % copyleft advocates on this point. I think it's just a question that is
  1445. % rarely opined on but often asked, so it's fitting for this Guide to cover
  1446. % it, and for addition on this point in the FAQ.
  1447. \medskip
  1448. \label{GPLv2s2-at-no-charge}
  1449. The next phrase of note in GPLv2~\S2(b) is ``licensed \ldots at no charge.''
  1450. This phrase confuses many. The sloppy reader points out this as ``a
  1451. contradiction in GPL'' because (in their confused view) that clause of GPLv2~\S2 says that re-distributors cannot
  1452. charge for modified versions of GPL'd software, but GPLv2~\S1 says that
  1453. they can. Avoid this confusion: the ``at no charge'' \textbf{does not} prohibit re-distributors from
  1454. charging when performing the acts governed by copyright
  1455. law,\footnote{Recall that you could by default charge for any acts not
  1456. governed by copyright law, because the license controls are confined
  1457. by copyright.} but rather that they cannot charge a fee for the
  1458. \emph{license itself}. In other words, redistributors of (modified
  1459. and unmodified) GPL'd works may charge any amount they choose for
  1460. performing the modifications on contract or the act of transferring
  1461. the copy to the customer, but they may not charge a separate licensing
  1462. fee for the software.
  1463. GPLv2~\S2(b) further states that the software must ``be licensed \ldots to all
  1464. third parties.'' This too yields some confusion, and feeds the
  1465. misconception mentioned earlier --- that all modified versions must be made
  1466. available to the public at large. However, the text here does not say
  1467. that. Instead, it says that the licensing under terms of the GPL must
  1468. extend to anyone who might, through the distribution chain, receive a copy
  1469. of the software. Distribution to all third parties is not mandated here,
  1470. but GPLv2~\S2(b) does require re-distributors to license the whole work in
  1471. a way that extends to all third parties who may ultimately receive a
  1472. copy of the software.
  1473. In summary, GPLv2\ 2(b) says what terms under which the third parties must
  1474. receive this no-charge license. Namely, they receive it ``under the terms
  1475. of this License'', the GPLv2. When an entity \emph{chooses} to redistribute
  1476. a work based on GPL'd software, the license of that whole
  1477. work must be GPL and only GPL\@. In this manner, GPLv2~\S2(b) dovetails nicely
  1478. with GPLv2~\S6 (as discussed in Section~\ref{GPLv2s6} of this tutorial).
  1479. \medskip
  1480. The final paragraph of GPLv2~\S2 is worth special mention. It is possible and
  1481. quite common to aggregate various software programs together on one
  1482. distribution medium. Computer manufacturers do this when they ship a
  1483. pre-installed hard drive, and GNU/Linux distribution vendors do this to
  1484. give a one-stop CD or URL for a complete operating system with necessary
  1485. applications. The GPL very clearly permits such ``mere aggregation'' with
  1486. programs under any license. Despite what you hear from its critics, the
  1487. GPL is nothing like a virus, not only because the GPL is good for you and
  1488. a virus is bad for you, but also because simple contact with a GPL'd
  1489. code-base does not impact the license of other programs. A programmer must
  1490. expend actual effort to cause a work to fall under the terms
  1491. of the GPL. Redistributors are always welcome to simply ship GPL'd
  1492. software alongside proprietary software or other unrelated Free Software,
  1493. as long as the terms of GPL are adhered to for those packages that are
  1494. truly GPL'd.
  1495. %FIXME: need discussion of GPLv2's system library exception somewhere in here.
  1496. \subsection{Right to Private Modification}
  1497. \label{gplv2-private-modification}
  1498. The issue of private modifications of GPLv2'd works deserves special
  1499. attention. While these rights are clearly explicit in GPLv3~\S2\P2 (see
  1500. \S~\ref{GPLv3S2} of this tutorial for details), the permission to create
  1501. private modifications is mostly implicit in GPLv2. Most notably, the
  1502. requirements of GPLv2~\S2 (and GPLv2~\S3, which will be discussed next) are
  1503. centered around two different copyright controls: both modification
  1504. \emph{and} distribution. As such, GPLv2~\S2's requirements need only be met
  1505. when a modified version is distributed; one need not follow them for modified
  1506. versions that are not distributed.\footnote{As a matter of best practice, it's
  1507. useful to assume that all software may eventually be distributed later,
  1508. even if there no plans for distribution at this time. Too often, GPL
  1509. violations occur because of a late distribution decision of software that
  1510. was otherwise never intended for distribution.}
  1511. However, the careful reader of GPLv2 will notice that, unlike GPLv3, no other
  1512. clauses of the license actually give explicit permission to make private
  1513. modifications. Since modification of software is a control governed by
  1514. copyright, a modifier needs permission from the copyright holder to engage in
  1515. that activity.
  1516. In practice, however, traditional GPLv2 interpretation has always assumed
  1517. that blanket permission to create non-distributed modified versions was
  1518. available, and the
  1519. \href{http://www.gnu.org/licenses/gpl-faq.html#GPLRequireSourcePostedPublic}{FSF
  1520. has long opined that distribution of modified versions is never mandatory}.
  1521. This issue is one of many where GPLv3 clarifies in explicit text the implicit
  1522. policy and intent that was solidified via long-standing interpretation of
  1523. GPLv2.
  1524. \section{GPLv2~\S3: Producing Binaries}
  1525. \label{GPLv2s3}
  1526. Software is a strange beast when compared to other copyrightable works.
  1527. It is currently impossible to make a film or a book that can be truly
  1528. obscured. Ultimately, the full text of a novel, even one written by
  1529. William Faulkner, must be presented to the reader as words in some
  1530. human-readable language so that they can enjoy the work. A film, even one
  1531. directed by David Lynch, must be perceptible by human eyes and ears to
  1532. have any value.
  1533. Software is not so. While the source code --- the human-readable
  1534. representation of software --- is of keen interest to programmers, users and
  1535. programmers alike cannot make the proper use of software in that
  1536. human-readable form. Binary code --- the ones and zeros that the computer
  1537. can understand --- must be predicable and attainable for the software to
  1538. be fully useful. Without the binaries, be they in object or executable
  1539. form, the software serves only the didactic purposes of computer science.
  1540. Under copyright law, binary representations of the software are simply
  1541. modified versions (and/or derivative works) of the source code. Applying a systematic process (i.e.,
  1542. ``compilation''\footnote{``Compilation'' in this context refers to the
  1543. automated computing process of converting source code into binaries. It
  1544. has absolutely nothing to do with the term ``compilation'' in copyright statues.}) to a work of source code yields binary code. The binary
  1545. code is now a new work of expression fixed in the tangible medium of
  1546. electronic file storage.
  1547. Therefore, for GPL'd software to be useful, the GPL, since it governs the
  1548. rules for creation of modified works, must grant permission for the
  1549. generation of binaries. Furthermore, notwithstanding the relative
  1550. popularity of source-based GNU/Linux distributions like Gentoo, users find
  1551. it extremely convenient to receive distribution of binary software. Such
  1552. distribution is the redistribution of modified works of the software's
  1553. source code. GPLv2~\S3 addresses the matter of creation and distribution of
  1554. binary versions.
  1555. Under GPLv2~\S3, binary versions may be created and distributed under the
  1556. terms of GPLv2~\S1--2, so all the material previously discussed applies
  1557. here. However, GPLv2~\S3 must go a bit further. Access to the software's
  1558. source code is an incontestable prerequisite for the exercise of the
  1559. fundamental freedoms to modify and improve the software. Making even
  1560. the most trivial changes to a software program at the binary level is
  1561. effectively impossible. GPLv2~\S3 must ensure that the binaries are never
  1562. distributed without the source code, so that these freedoms are passed
  1563. through the distribution chain.
  1564. GPLv2~\S3 permits distribution of binaries, and then offers three options for
  1565. distribution of source code along with binaries. The most common and the
  1566. least complicated is the option given under GPLv2~\S3(a).
  1567. \label{GPLv2s3a}
  1568. GPLv2~\S3(a) offers the option to directly accompany the source code alongside
  1569. the distribution of the binaries. This is by far the most convenient
  1570. option for most distributors, because it means that the source-code
  1571. provision obligations are fully completed at the time of binary
  1572. distribution (more on that later).
  1573. \subsection{Complete, Corresponding Source (CCS)}
  1574. Under GPLv2~\S3(a), the source code provided must be the ``corresponding source
  1575. code.'' Here ``corresponding'' primarily means that the source code
  1576. provided must be that code used to produce the binaries being distributed.
  1577. That source code must also be ``complete''. GPLv2~\S3's penultimate paragraph
  1578. explains in detail what is meant by ``complete''. In essence, it is all
  1579. the material that a programmer of average skill would need to actually use
  1580. the source code to produce the binaries she has received. Complete source
  1581. is required so that, if the licensee chooses, she should be able to
  1582. exercise her freedoms to modify and redistribute changes. Without the
  1583. complete source, it would not be possible to make changes that were
  1584. actually directly derived from the version received.
  1585. Based on the appearance of those two words, GPL theorists will often refer to
  1586. the source code required under the previsions of this section as ``Complete,
  1587. Corresponding Source'', sometimes abbreviated as CCS\@. CCS is not a formal,
  1588. defined term in GPLv2, but rather, GPL theorists coined the acronym CCS to
  1589. embody not just the concepts of ``complete'' and ``corresponding'' as found
  1590. in GPLv2, but the entirety of GPLv2's requirements for source code
  1591. provisioning. In other words, GPL theorists might say: ``the company
  1592. provided some source, but it wasn't CCS'', which would mean the source code
  1593. failed in some ways to meet some term of GPLv2.
  1594. \label{GPLv2s3-build-scripts}
  1595. Indeed, CCS needs completely include not just that source which is directly
  1596. translated by the compiler into object code, but other materials necessary to
  1597. convert the source into equivalent binaries. Specifically, GPLv2~\S3
  1598. requires that the source code include ``meta-material'' like scripts,
  1599. interface definitions, and other material that is used to ``control
  1600. compilation and installation'' of the binaries. In this manner, those
  1601. further down the distribution chain are assured that they have the unabated
  1602. freedom to build their own modified works from the sources provided.
  1603. This requirement is not merely of theoretical value. If you pay a high price
  1604. for a copy of GPL'd binaries (which comes with CCS, of course), you have the
  1605. freedom to redistribute that work at any fee you choose, or not at all.
  1606. Sometimes, companies attempt a GPL-violating cozenage whereby they produce
  1607. very specialized binaries (perhaps for an obscure architecture). They then
  1608. give source code that does correspond, but withhold the ``incantations'' and
  1609. build plans they used to make that source compile into the specialized
  1610. binaries. Such distributions violate GPL, since the downstream users cannot
  1611. effectively ``control compilation and installation'' of the binaries.
  1612. \subsection{Additional Source Provision Options}
  1613. Software distribution comes in many
  1614. forms. Embedded manufacturers, for example, have the freedom to put
  1615. GPL'd software into mobile devices with very tight memory and space
  1616. constraints. In such cases, putting the source right alongside the
  1617. binaries on the machine itself might not be an option. While it is
  1618. recommended that this be the default way that people comply with GPL, the
  1619. GPL does provide options when such distribution is unfeasible.
  1620. \label{GPLv2s3-medium-customarily}
  1621. GPLv2~\S3, therefore, allows source code to be provided on any physical
  1622. ``medium customarily used for software interchange.'' By design, this
  1623. phrase covers a broad spectrum --- the phrase seeks to pre-adapt to
  1624. changes in technology. When GPLv2 was first published in June
  1625. 1991, distribution on magnetic tape was still common, and CD was
  1626. relatively new. By 2002, CD was the default. By 2007, DVD's were the
  1627. default. Now, it's common to give software on USB drives and SD cards. This
  1628. language in the license must adapt with changing technology.
  1629. Meanwhile, the binding created by the word ``customarily'' is key. Many
  1630. incorrectly believe that distributing binary on CD and source on the
  1631. Internet is acceptable. In the corporate world in industrialized countries, it is indeed customary to
  1632. simply download a CDs' worth of data quickly. However, even today in the USA, many computer users are not connected to the Internet, and most people connected
  1633. to the Internet still have limited download speeds. Downloading
  1634. CDs full of data is not customary for them in the least. In some cities
  1635. in Africa, computers are becoming more common, but Internet connectivity
  1636. is still available only at a few centralized locations. Thus, the
  1637. ``customs'' here are normalized for a worldwide userbase. Simply
  1638. providing source on the Internet --- while it is a kind, friendly and
  1639. useful thing to do --- is not usually sufficient.
  1640. Note, however, a major exception to this rule, given by the last paragraph
  1641. of GPLv2~\S3. \emph{If} distribution of the binary files is made only on the
  1642. Internet (i.e., ``from a designated place''), \emph{then} simply providing
  1643. the source code right alongside the binaries in the same place is
  1644. sufficient to comply with GPLv2~\S3.
  1645. \medskip
  1646. As is shown above, under GPLv2~\S3(a), embedded manufacturers can put the
  1647. binaries on the device and ship the source code along on a CD\@. However,
  1648. sometimes this turns out to be too costly. Including a CD with every
  1649. device could prove too costly, and may practically (although not legally)
  1650. prohibit using GPL'd software. For this situation and others like it, GPLv2\S~3(b) is available.
  1651. \label{GPLv2s3b}
  1652. GPLv2~\S3(b) allows a distributor of binaries to instead provide a written
  1653. offer for source code alongside those binaries. This is useful in two
  1654. specific ways. First, it may turn out that most users do not request the
  1655. source, and thus the cost of producing the CDs is saved --- a financial
  1656. and environmental windfall. In addition, along with a GPLv2~\S3(b) compliant
  1657. offer for source, a binary distributor might choose to \emph{also} give a
  1658. URL for source code. Many who would otherwise need a CD with source might
  1659. turn out to have those coveted high bandwidth connections, and are able to
  1660. download the source instead --- again yielding environmental and financial
  1661. windfalls.
  1662. However, note that regardless of how many users prefer to get the
  1663. source online, GPLv2~\S3(b) does place lasting long-term obligations on the
  1664. binary distributor. The binary distributor must be prepared to honor
  1665. that offer for source for three years and ship it out (just as they
  1666. would have had to do under GPLv2~\S3(a)) at a moment's notice when they
  1667. receive such a request. There is real organizational cost here:
  1668. support engineers must be trained how to route source requests, and
  1669. source CD images for every release version for the last three years
  1670. must be kept on hand to burn such CDs quickly. The requests might not
  1671. even come from actual customers; the offer for source must be valid
  1672. for ``any third party''.
  1673. That phrase is another place where some get confused --- thinking again
  1674. that full public distribution of source is required. The offer for source
  1675. must be valid for ``any third party'' because of the freedoms of
  1676. redistribution granted by GPLv2~\S\S1--2. A company may ship a binary image
  1677. and an offer for source to only one customer. However, under GPL, that
  1678. customer has the right to redistribute that software to the world if she
  1679. likes. When she does, that customer has an obligation to make sure that
  1680. those who receive the software from her can exercise their freedoms under
  1681. GPL --- including the freedom to modify, rebuild, and redistribute the
  1682. source code.
  1683. GPLv2~\S3(c) is created to save her some trouble, because by itself GPLv2~\S3(b)
  1684. would unfairly favor large companies. GPLv2~\S3(b) allows the
  1685. separation of the binary software from the key tool that people can use
  1686. to exercise their freedom. The GPL permits this separation because it is
  1687. good for re-distributors, and those users who turn out not to need the
  1688. source. However, to ensure equal rights for all software users, anyone
  1689. along the distribution chain must have the right to get the source and
  1690. exercise those freedoms that require it.
  1691. Meanwhile, GPLv2~\S3(b)'s compromise primarily benefits companies that
  1692. distribute binary software commercially. Without GPLv2~\S3(c), that benefit
  1693. would be at the detriment of the companies' customers; the burden of
  1694. source code provision would be unfairly shifted to the companies'
  1695. customers. A customer, who had received binaries with a GPLv2~\S3(b)-compliant
  1696. offer, would be required under GPLv2 (sans GPLv2~\S3(c)) to acquire the source,
  1697. merely to give a copy of the software to a friend who needed it. GPLv2~\S3(c)
  1698. reshifts this burden to entity who benefits from GPLv2~\S3(b).
  1699. GPLv2~\S3(c) allows those who undertake \emph{noncommercial} distribution to
  1700. simply pass along a GPLv2~\S3(b)-compliant source code offer. The customer who
  1701. wishes to give a copy to her friend can now do so without provisioning the
  1702. source, as long as she gives that offer to her friend. By contrast, if
  1703. she wanted to go into business for herself selling CDs of that software,
  1704. she would have to acquire the source and either comply via GPLv2~\S3(a), or
  1705. write her own GPLv2~\S3(b)-compliant source offer.
  1706. This process is precisely the reason why a GPLv2~\S3(b) source offer must be
  1707. valid for all third parties. At the time the offer is made, there is no
  1708. way of knowing who might end up noncommercially receiving a copy of the
  1709. software. Companies who choose to comply via GPLv2~\S3(b) must thus be
  1710. prepared to honor all incoming source code requests. For this and the
  1711. many other additional necessary complications under GPLv2~\S\S3(b--c), it is
  1712. only rarely a better option than complying via GPLv2~\S3(a).
  1713. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  1714. \chapter{GPL's Implied Patent Grant}
  1715. \label{gpl-implied-patent-grant}
  1716. We digress again briefly from our section-by-section consideration of GPLv2
  1717. to consider the interaction between the terms of GPL and patent law. The
  1718. GPLv2, despite being silent with respect to patents, actually confers on its
  1719. licensees more rights to a licensor's patents than those licenses that
  1720. purport to address the issue. This is the case because patent law, under
  1721. the doctrine of implied license, gives to each distributee of a patented
  1722. article a license from the distributor to practice any patent claims owned
  1723. or held by the distributor that cover the distributed article. The
  1724. implied license also extends to any patent claims owned or held by the
  1725. distributor that cover ``reasonably contemplated uses'' of the patented
  1726. article. To quote the Federal Circuit Court of Appeals, the highest court
  1727. for patent cases other than the Supreme Court:
  1728. \begin{quotation}
  1729. Generally, when a seller sells a product without restriction, it in
  1730. effect promises the purchaser that in exchange for the price paid, it will
  1731. not interfere with the purchaser's full enjoyment of the product
  1732. purchased. The buyer has an implied license under any patents of the
  1733. seller that dominate the product or any uses of the product to which the
  1734. parties might reasonably contemplate the product will be put.
  1735. \end{quotation}
  1736. Hewlett-Packard Co. v. Repeat-O-Type Stencil Mfg. Corp., Inc., 123 F.3d
  1737. 1445, 1451 (Fed. Cir. 1997).
  1738. Of course, Free Software is licensed, not sold, and there are indeed
  1739. restrictions placed on the licensee, but those differences are not likely
  1740. to prevent the application of the implied license doctrine to Free
  1741. Software, because software licensed under the GPL grants the licensee the
  1742. right to make, use, and sell the software, each of which are exclusive
  1743. rights of a patent holder. Therefore, although the GPLv2 does not expressly
  1744. grant the licensee the right to do those things under any patents the
  1745. licensor may have that cover the software or its reasonably contemplated
  1746. uses, by licensing the software under the GPLv2, the distributor impliedly
  1747. licenses those patents to the GPLv2 licensee with respect to the GPLv2'd
  1748. software.
  1749. An interesting issue regarding this implied patent license of GPLv2'd
  1750. software is what would be considered ``uses of the [software] to which
  1751. the parties might reasonably contemplate the product will be put.'' A
  1752. clever advocate may argue that the implied license granted by GPLv2 is
  1753. larger in scope than the express license in other Free Software
  1754. licenses with express patent grants, in that the patent license
  1755. clause of many of those other Free Software licenses are specifically
  1756. limited to the patent claims covered by the code as licensed by the patentee.
  1757. In contrast, a GPLv2 licensee, under the doctrine of implied patent license,
  1758. is free to practice any patent claims held by the licensor that cover
  1759. ``reasonably contemplated uses'' of the GPL'd code, which may very well
  1760. include creation and distribution of modified works since the GPL's terms,
  1761. under which the patented code is distributed, expressly permits such activity.
  1762. Further supporting this result is the Federal Circuit's pronouncement that
  1763. the recipient of a patented article has, not only an implied license to
  1764. make, use, and sell the article, but also an implied patent license to
  1765. repair the article to enable it to function properly, Bottom Line Mgmt.,
  1766. Inc. v. Pan Man, Inc., 228 F.3d 1352 (Fed. Cir. 2000). Additionally, the
  1767. Federal Circuit extended that rule to include any future recipients of the
  1768. patented article, not just the direct recipient from the distributor.
  1769. This theory comports well with the idea of Free Software, whereby software
  1770. is distributed among many entities within the community for the purpose
  1771. of constant evolution and improvement. In this way, the law of implied
  1772. patent license used by the GPLv2 ensures that the community mutually
  1773. benefits from the licensing of patents to any single community member.
  1774. Note that simply because GPLv2'd software has an implied patent license does
  1775. not mean that any patents held by a distributor of GPLv2'd code become
  1776. worthless. To the contrary, the patents are still valid and enforceable
  1777. against either:
  1778. \begin{enumerate}
  1779. \renewcommand{\theenumi}{\alph{enumi}}
  1780. \renewcommand{\labelenumi}{\textup{(\theenumi)}}
  1781. \item any software other than that licensed under the GPLv2 by the patent
  1782. holder, and
  1783. \item any party that does not comply with the GPLv2
  1784. with respect to the licensed software.
  1785. \end{enumerate}
  1786. \newcommand{\compB}{$\mathcal{B}$}
  1787. \newcommand{\compA}{$\mathcal{A}$}
  1788. For example, if Company \compA{} has a patent on advanced Web browsing, but
  1789. also licenses a Web browsing program under the GPLv2, then it
  1790. cannot assert the patent against any party based on that party's use of
  1791. Company \compA{}'s GPL'd Web browsing software program, or on that party's
  1792. creation and use of modified versions of that GPL'd program. However, if a
  1793. party uses that program without
  1794. complying with the GPLv2, then Company \compA{} can assert both copyright
  1795. infringement claims against the non-GPLv2-compliant party and
  1796. infringement of the patent, because the implied patent license only
  1797. extends to use of the software in accordance with the GPLv2. Further, if
  1798. Company \compB{} distributes a competitive advanced Web browsing program
  1799. that is not a modified version of Company \compA{}'s GPL'd Web browsing software
  1800. program, Company \compA{} is free to assert its patent against any user or
  1801. distributor of that product. It is irrelevant whether Company \compB's
  1802. program is also distributed under the GPLv2, as Company \compB{} can not grant
  1803. implied licenses to Company \compA's patent.
  1804. This result also reassures companies that they need not fear losing their
  1805. proprietary value in patents to competitors through the GPLv2 implied patent
  1806. license, as only those competitors who adopt and comply with the GPLv2's
  1807. terms can benefit from the implied patent license. To continue the
  1808. example above, Company \compB{} does not receive a free ride on Company
  1809. \compA's patent, as Company \compB{} has not licensed-in and then
  1810. redistributed Company A's advanced Web browser under the GPLv2. If Company
  1811. \compB{} does do that, however, Company \compA{} still has not lost
  1812. competitive advantage against Company \compB{}, as Company \compB{} must then,
  1813. when it re-distributes Company \compA's program, grant an implied license
  1814. to any of its patents that cover the program. Further, if Company \compB{}
  1815. relicenses an improved version of Company A's program, it must do so under
  1816. the GPLv2, meaning that any patents it holds that cover the improved version
  1817. are impliedly licensed to any licensee. As such, the only way Company
  1818. \compB{} can benefit from Company \compA's implied patent license, is if it,
  1819. itself, distributes Company \compA's software program and grants an
  1820. implied patent license to any of its patents that cover that program.
  1821. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  1822. \chapter{Defending Freedom on Many Fronts}
  1823. Chapters~\ref{run-and-verbatim} and~\ref{source-and-binary} presented the
  1824. core freedom-defending provisions of GPLv2\@, which are in GPLv2~\S\S0--3.
  1825. GPLv2\S\S~4--7 of the GPLv2 are designed to ensure that GPLv2~\S\S0--3 are
  1826. not infringed, are enforceable, are kept to the confines of copyright law but
  1827. also not trumped by other copyright agreements or components of other
  1828. entirely separate legal systems. In short, while GPLv2~\S\S0--3 are the parts
  1829. of the license that defend the freedoms of users and programmers,
  1830. GPLv2~\S\S4--7 are the parts of the license that keep the playing field clear
  1831. so that \S\S~0--3 can do their jobs.
  1832. \section{GPLv2~\S4: Termination on Violation}
  1833. \label{GPLv2s4}
  1834. GPLv2~\S4 is GPLv2's termination clause. Upon first examination, it seems
  1835. strange that a license with the goal of defending users' and programmers'
  1836. freedoms for perpetuity in an irrevocable way would have such a clause.
  1837. However, upon further examination, the difference between irrevocability
  1838. and this termination clause becomes clear. (See~\ref{gplv2-irrevocable} for
  1839. expanded discussion of GPLv2 irrevocability.)
  1840. The GPL is irrevocable in the sense that once a copyright holder grants
  1841. rights for someone to copy, modify and redistribute the software under terms
  1842. of the GPL, they cannot later revoke that grant. Since the GPL has no
  1843. provision allowing the copyright holder to take such a prerogative, the
  1844. license is granted as long as the copyright remains in effect.\footnote{In
  1845. the USA, due to unfortunate legislation, the length of copyright is nearly
  1846. perpetual, even though the Constitution forbids perpetual copyright.} The
  1847. copyright holders have the right to relicense the same work under different
  1848. licenses (see Section~\ref{Proprietary Relicensing} of this tutorial), or to
  1849. stop distributing the GPLv2'd version (assuming GPLv2~\S3(b) was never used),
  1850. but they may not revoke the rights under GPLv2 already granted.
  1851. In fact, when an entity loses their right to copy, modify and distribute
  1852. GPL'd software, it is because of their \emph{own actions}, not that of the
  1853. copyright holder. The copyright holder does not decide when GPLv2~\S4
  1854. termination occurs (if ever); rather, the actions of the licensee determine
  1855. that.
  1856. Under copyright law, the GPL has granted various rights and freedoms to
  1857. the licensee to perform specific types of copying, modification, and
  1858. redistribution. By default, all other types of copying, modification, and
  1859. redistribution are prohibited. GPLv2~\S4 says that if you undertake any of
  1860. those other types (e.g., redistributing binary-only in violation of GPLv2~\S3),
  1861. then all rights under the license --- even those otherwise permitted for
  1862. those who have not violated --- terminate automatically.
  1863. GPLv2~\S4 makes GPLv2 enforceable. If licensees fail to adhere to the
  1864. license, then they are stuck without any permission under to engage in
  1865. activities covered by copyright law. They must completely cease and desist
  1866. from all copying, modification and distribution of the GPL'd software.
  1867. At that point, violating licensees must gain the forgiveness of the copyright
  1868. holders to have their rights restored. Alternatively, the violators could
  1869. negotiate another agreement, separate from GPL, with the copyright
  1870. holder. Both are common practice, although
  1871. \tutorialpartsplit{as discussed in \textit{A Practical Guide to GPL
  1872. Compliance}, there are }{Chapter~\ref{compliance-understanding-whos-enforcing}
  1873. explains further} key differences between these two very different uses of GPL.
  1874. \section{GPLv2~\S5: Acceptance, Copyright Style}
  1875. \label{GPLv2s5}
  1876. GPLv2~\S5 brings us to perhaps the most fundamental misconception and common
  1877. confusion about GPLv2\@. Because of the prevalence of proprietary software,
  1878. most users, programmers, and lawyers alike tend to be more familiar with
  1879. EULAs. EULAs are believed by their authors to be contracts, requiring
  1880. formal agreement between the licensee and the software distributor to be
  1881. valid. This has led to mechanisms like ``shrink-wrap'' and ``click-wrap''
  1882. as mechanisms to perform acceptance ceremonies with EULAs.
  1883. The GPL does not need contract law to ``transfer rights.'' Usually, no rights
  1884. are transferred between parties. By contrast, the GPL is primarily a permission
  1885. slip to undertake activities that would otherwise have been prohibited
  1886. by copyright law. As such, GPL needs no acceptance ceremony; the
  1887. licensee is not even required to accept the license.
  1888. However, without the GPL, the activities of copying, modifying and
  1889. distributing the software would have otherwise been prohibited. So, the
  1890. GPL says that you only accepted the license by undertaking activities that
  1891. you would have otherwise been prohibited without your license under GPL\@.
  1892. This is a certainly subtle point, and requires a mindset quite different
  1893. from the contractual approach taken by EULA authors.
  1894. An interesting side benefit to GPLv2~\S5 is that the bulk of users of Free
  1895. Software are not required to accept the license. Undertaking fair and
  1896. unregulated use of the work, for example, does not bind you to the GPL,
  1897. since you are not engaging in activity that is otherwise controlled by
  1898. copyright law. Only when you engage in those activities that might have an
  1899. impact on the freedom of others does license acceptance occur, and the
  1900. terms begin to bind you to fair and equitable sharing of the software. In
  1901. other words, the GPL only kicks in when it needs to for the sake of
  1902. freedom.
  1903. While GPL is by default a copyright license, it is certainly still possible
  1904. to consider GPL as a contract as well. For example, some distributors chose
  1905. to ``wrap'' their software in an acceptance ceremony to the GPL, and nothing in
  1906. the GPL prohibits that use. Furthermore, the ruling in \textit{Jacobsen
  1907. v. Katzer, 535 F.3d 1373, 1380 (Fed.Cir.2008)} indicates that \textbf{both}
  1908. copyright and contractual remedies may be sought by a copyright holder
  1909. seeking to enforce a license designed to uphold software freedom.
  1910. % FIXME-LATER: Write this
  1911. %\section{Using GPL Both as a Contract and Copyright License}
  1912. \section{GPLv2~\S6: GPL, My One and Only}
  1913. \label{GPLv2s6}
  1914. A point that was glossed over in Section~\ref{GPLv2s4}'s discussion of GPLv2~\S4
  1915. was the irrevocable nature of the GPL\@. The GPLv2 is indeed irrevocable,
  1916. and it is made so formally by GPLv2~\S6.
  1917. The first sentence in GPLv2~\S6 ensures that as software propagates down the
  1918. distribution chain, that each licensor can pass along the license to each
  1919. new licensee. Under GPLv2~\S6, the act of distributing automatically grants a
  1920. license from the original licensor to the next recipient. This creates a
  1921. chain of grants that ensure that everyone in the distribution has rights
  1922. under the GPLv2\@. In a mathematical sense, this bounds the bottom ---
  1923. making sure that future licensees get no fewer rights than the licensee before.
  1924. The second sentence of GPLv2~\S6 does the opposite; it bounds from the top. It
  1925. prohibits any licensor along the distribution chain from placing
  1926. additional restrictions on the user. In other words, no additional
  1927. requirements may trump the rights and freedoms given by GPLv2\@.
  1928. The final sentence of GPLv2~\S6 makes it abundantly clear that no individual
  1929. entity in the distribution chain is responsible for the compliance of any
  1930. other. This is particularly important for noncommercial users who have
  1931. passed along a source offer under GPLv2~\S3(c), as they cannot be assured that
  1932. the issuer of the offer will honor their GPLv2~\S3 obligations.
  1933. In short, GPLv2~\S6 says that your license for the software is your one and
  1934. only copyright license allowing you to copy, modify and distribute the
  1935. software.
  1936. GPLv2~\S6 is GPLv2's ``automatic downstream licensing''
  1937. provision\footnote{This section was substantially expanded for clarity and
  1938. detail in \hyperref[GPLv3s10]{GPLv3~\S10}.}. Each time you
  1939. redistribute a GPL'd program, the recipient automatically receives a license
  1940. from each original licensor to copy, distribute or modify the program subject
  1941. to the conditions of the license. The redistributor need not take any
  1942. to ensure the downstream recipient's acceptance of the license terms.
  1943. This places every copyright holder in the chain of descent of the code
  1944. in legal privity, or direct relationship, with every downstream
  1945. redistributor. Two legal effects follow. First, downstream parties
  1946. who remain in compliance have valid permissions for all actions
  1947. (including modification and redistribution) even if their immediate upstream
  1948. supplier of the software has been terminated for license
  1949. violation\footnote{\label{German-reinstatement-footnote} While this is legally true, as a practical matter, a
  1950. failure of ``complete, corresponding source'' (CCS) provisioning by an
  1951. upstream could make it effectively impossible for a downstream party to
  1952. engage in a commercial redistribution pursuant to
  1953. \hyperref[GPLv2s3]{GPLv2~\S3(a--b)}. (\S~\ref{upstream} in the Compliance
  1954. Guide portion of this tutorial discussed related details.)}.
  1955. Downstream's
  1956. licensed rights are not dependent on compliance of their upstream, because
  1957. their licenses issue directly from the copyright holder. Second, automatic
  1958. termination cannot be cured by obtaining additional copies from an alternate
  1959. supplier: the license permissions emanate only from the original licensors,
  1960. and if they have automatically terminated permission, no act by any
  1961. intermediate license holder can restore those terminated
  1962. rights\footnote{While nearly all attorneys and copyleft theorists are in
  1963. agreement on this point, German copyleft legal expert
  1964. \href{http://www.jbb.de/en/attorneys/till-jaeger/}{Till Jaeger}
  1965. vehemently disagrees. Jaeger's position is as follows: under German
  1966. copyright law, a new copy of GPL'd software is a ``fresh'' license under
  1967. GPL, and if compliance continues from that point further, the violator's
  1968. permissions under copyright law are automatically restored, notwithstanding
  1969. the strict termination provision in \hyperref[GPLv2s4]{GPLv2~\S4}.
  1970. However, in
  1971. practice, this issue is only salient with regard to \hyperref[Proprietary
  1972. Relicensing]{proprietary relicensing} business models, since other copyright
  1973. holders typically formally restore distributions rights once the only
  1974. remaining compliance issue is ``you lost copyright permission due to
  1975. GPLv2~\S4''. Therefore, the heated debates, which have raged between
  1976. Jaeger and almost everyone else in the copyleft community for nearly a
  1977. decade, regard an almost moot and wholly esoteric legal detail.}.
  1978. \section{GPLv2 Irrevocability}
  1979. \label{gplv2-irrevocable}
  1980. This section digresses briefly to examine the manner in which GPLv2\S\S~4--6
  1981. interact together to assure that the license grant is irrevocable.
  1982. There are two legal theories why a contributor cannot terminate their license
  1983. grant. First is an argument that the text of the GPL prevents it; second is
  1984. that a contributor would be estopped from succeeding on an infringement claim
  1985. for continued use of the code even if it wasn't removed.
  1986. \subsection{The text of the GPLv2}
  1987. The GPLv2 have several provisions that, when taken together, can be construed
  1988. as an irrevocable license from each contributor. First, the GPLv2 says ``by
  1989. \emph{modifying} or distributing the Program (or any work based on the Program), you
  1990. indicate your acceptance of this License to do so, and all its terms and
  1991. conditions for copying, distributing or modifying the Program or works based
  1992. on it'' (GPLv2\S5, emphasis added). A contributor by definition is modifying
  1993. the code and therefore has agreed to all the terms in the GPLv2, which
  1994. includes the web of mechanisms in the GPLv2 that ensure the code can be used
  1995. by all.
  1996. More specifically, the downstream license grant says ``the recipient
  1997. automatically receives a license from the original licensor to copy,
  1998. distribute or modify the Program subject to these terms and conditions.''
  1999. (GPLv2\S6). So in this step, the contributor has granted a license to the
  2000. downstream, on the condition that the downstream complies with the license
  2001. terms.
  2002. That license granted to downstream is irrevocable, again provided that the
  2003. downstream user complies with the license terms: ``[P]arties who have
  2004. received copies, or rights, from you under this License will not have their
  2005. licenses terminated so long as such parties remain in full compliance''
  2006. (GPLv2\S4).
  2007. Thus, anyone downstream of the contributor (which is anyone using the
  2008. contributor's code), has an irrevocable license from the contributor. A
  2009. contributor may claim to revoke their grant, and subsequently sue for
  2010. copyright infringement, but a court would likely find the revocation was
  2011. ineffective and the downstream user had a valid license defense to a claim of
  2012. infringement.
  2013. Nevertheless, for purposes of argument, we will assume that for some
  2014. reason the GPLv2 is not enforceable against the contributor\footnote{For
  2015. example, the argument has been made that there may be a failure of
  2016. consideration on the part of the contributor. While \textit{Jacobsen
  2017. v. Katzer}, 535 F.3d 1373 (Fed. Cir. 2008) is accepted as holding that
  2018. there is consideration received by the contributor in a FOSS license, the
  2019. posture of the case was one where the contributor advocated for the theory,
  2020. not against it. The author is not aware of any other decisions that have analyzed
  2021. the question in any depth, so it perhaps could be challenged in the right
  2022. factual situation.}, or that the irrevocable license can be
  2023. revoked\footnote{A contract without a definable duration can be terminated on
  2024. reasonable notice. \textit{Great W. Distillery Prod. v. John A. Wathen Distillery
  2025. Co.}, 10 Cal. 2d 442, 447, 74 P.2d 745, 747 (1937). The term nevertheless
  2026. can be a term of indefinite length where its continuing effect is tied to
  2027. the conduct of the parties. \emph{Id}.}. In that case, the application of
  2028. promissory estoppel will likely mean that the contributor still cannot
  2029. enforce their copyright against downstream users.
  2030. \subsection{Promissory estoppel}
  2031. ``Promissory estoppel'' is a legal theory that says, under some
  2032. circumstances, a promise is enforceable against the promisee even after the
  2033. promisee tries to renege on the promise. The test for how and when promissory
  2034. estoppel applies differs from state to state, but generally where there is a
  2035. ``promise which the promisor should reasonably expect to induce action or
  2036. forbearance on the part of the promisee or a third person and which does
  2037. induce such action or forbearance is binding if injustice can be avoided only
  2038. by enforcement of the promise.''\footnote{\textit{Kajima/Ray Wilson v. Los Angeles
  2039. Cty. Metro. Transp. Auth.}, 23 Cal. 4th 305, 310, 1 P.3d 63, 66 (2000), \emph{citing}
  2040. Restatement (Second) of Contracts \S 90(1) (1979).} Breaking it down, it is:
  2041. \begin{enumerate}
  2042. \item where there is a clear and definite promise;
  2043. \item where the promisor has a reasonable expectation that the offer will
  2044. induce action or forbearance on the part of the promisee;
  2045. \item which does induce actual and reasonable action or forbearance by the promisee; and
  2046. \item which causes a detriment which can only be avoided by the enforcement
  2047. of the promise.
  2048. \end{enumerate}
  2049. In this case, the promisor is the contributor. This should be an easy
  2050. standard to meet in any widely used software.
  2051. \begin{enumerate}
  2052. \item The promise is contained in the GPL, which is a promise that one can
  2053. continue to use the licensed software as long as the terms of the license
  2054. are met.
  2055. \item A contributor knows that there is a broad user base and users consume
  2056. the software relying on the grant in the GPL as assuring their continued
  2057. ability to use the software (one might even say it is the \textit{sine qua
  2058. non} of the intent of the GPL).
  2059. \item Users do, in fact, rely on the promises in the GPL, as they ingest the software
  2060. and base their businesses on their continued ability to use the software.
  2061. \item Whether the user will suffer detriment is case-specific, but using
  2062. Linux, a software program that is often fundamental to the operation of a
  2063. business, as an example, the loss of its use would have a significantly
  2064. detrimental, perhaps even fatal, effect on the continued operation of the
  2065. business.
  2066. \end{enumerate}
  2067. \subsection{Conclusion}
  2068. Whether as a matter of a straightforward contractual obligation, or as a
  2069. matter of promissory estoppel, a contributor's attempt to revoke a copyright
  2070. license grant and then enforce their copyright against a user is highly
  2071. unlikely to succeed.
  2072. \section{GPLv2~\S7: ``Give Software Liberty or Give It Death!''}
  2073. \label{GPLv2s7}
  2074. In essence, GPLv2~\S7 is a verbosely worded way of saying for non-copyright
  2075. systems what GPLv2~\S6 says for copyright. If there exists any reason that a
  2076. distributor knows of that would prohibit later licensees from exercising
  2077. their full rights under GPL, then distribution is prohibited.
  2078. Originally, this was designed as the title of this section suggests --- as
  2079. a last ditch effort to make sure that freedom was upheld. However, in
  2080. modern times, it has come to give much more. Now that the body of GPL'd
  2081. software is so large, patent holders who would want to be distributors of
  2082. GPL'd software have a tough choice. They must choose between avoiding
  2083. distribution of GPL'd software that exercises the teachings of their
  2084. patents, or grant a royalty-free, irrevocable, non-exclusive license to
  2085. those patents. Many companies have chosen the latter.
  2086. Thus, GPLv2~\S7 rarely gives software death by stopping its distribution.
  2087. Instead, it is inspiring patent holders to share their patents in the same
  2088. freedom-defending way that they share their copyrighted works.
  2089. \section{GPLv2~\S8: Excluding Problematic Jurisdictions}
  2090. \label{GPLv2s8}
  2091. GPLv2~\S8 is rarely used by copyright holders. Its intention is that if a
  2092. particular country, say Unfreedonia, grants particular patents or allows
  2093. copyrighted interfaces (no country to our knowledge even permits those
  2094. yet), that the GPLv2'd software can continue in free and unabated
  2095. distribution in the countries where such controls do not exist.
  2096. As far as is currently known, GPLv2~\S8 has very rarely been formally used by
  2097. copyright holders. Admittedly, some have used GPLv2~\S8 to explain various
  2098. odd special topics of distribution (usually related in some way to
  2099. GPLv2~\S7). However, generally speaking, this section is not proven
  2100. particularly useful in the more than two decades of GPLv2 history.
  2101. Meanwhile, despite many calls by the FSF (and others) for those licensors who
  2102. explicitly use this section to come forward and explain their reasoning, no
  2103. one ever did. Furthermore, research conducted during the GPLv3 drafting
  2104. process found exactly one licensor who had invoked this section to add an
  2105. explicit geographical distribution limitation, and the reasoning for that one
  2106. invocation was not fitting with FSF's intended spirit of GPLv2~\S8. As such,
  2107. GPLv2~\S8 was not included at all in GPLv3.
  2108. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  2109. \chapter{Odds, Ends, and Absolutely No Warranty}
  2110. GPLv2~\S\S0--7 constitute the freedom-defending terms of the GPLv2. The remainder
  2111. of the GPLv2 handles administrivia and issues concerning warranties and
  2112. liability.
  2113. \section{GPLv2~\S9: FSF as Stewards of GPL}
  2114. \label{GPLv2s9}
  2115. FSF reserves the exclusive right to publish future versions of the GPL\@;
  2116. GPLv2~\S9 expresses this. While the stewardship of the copyrights on the body
  2117. of GPL'd software around the world is shared among thousands of
  2118. individuals and organizations, the license itself needs a single steward.
  2119. Forking of the code is often regrettable but basically innocuous. Forking
  2120. of licensing is disastrous.
  2121. (Chapter~\ref{tale-of-two-copylefts} discusses more about the various
  2122. versions of GPL.)
  2123. \section{GPLv2~\S10: Relicensing Permitted}
  2124. \label{GPLv2s10}
  2125. GPLv2~\S10 reminds the licensee of what is already implied by the nature of
  2126. copyright law. Namely, the copyright holder of a particular software
  2127. program has the prerogative to grant alternative agreements under separate
  2128. copyright licenses.
  2129. \section{GPLv2~\S11: No Warranty}
  2130. \label{GPLv2s11}
  2131. Most warranty disclaimer language shouts at you. The
  2132. \href{http://www.law.cornell.edu/ucc/2/2-316}{Uniform Commercial
  2133. Code~\S2-316}, which most of the USA's states and commonwealths have adopted as their local
  2134. law, allows disclaimers of warranty, provided that the disclaimer is ``conspicuous''.
  2135. There is apparently general acceptance that \textsc{all caps} is the
  2136. preferred way to make something conspicuous, and that has over decades worked
  2137. its way into the voodoo tradition of warranty disclaimer writing.
  2138. That said, there is admittedly some authority under USA law suggesting that
  2139. conspicuousness can be established by
  2140. capitalization and is absent when a disclaimer has the same typeface as the
  2141. terms surrounding it (see \textit{Stevenson v.~TRW, Inc.}, 987 F.2d 288, 296
  2142. (5th Cir.~1993)). While GPLv3's drafters doubted that such authority would
  2143. apply to copyright licenses like the GPL, the FSF has nevertheless left
  2144. warranty and related disclaimers in \textsc{all caps} throughout all versions
  2145. of GPL\@.\footnote{One of the authors of this tutorial, Bradley M.~Kuhn, has
  2146. often suggested the aesthetically preferable compromise of a
  2147. \textsc{specifically designed ``small caps'' font, such as this one, as an
  2148. alternative to} WRITING IN ALL CAPS IN THE DEFAULT FONT (LIKE THIS),
  2149. since the latter adds more ugliness than conspicuousness. Kuhn once
  2150. engaged in reversion war with a lawyer who disagreed, but that lawyer never
  2151. answered Kuhn's requests for case law that argues THIS IS INHERENTLY MORE
  2152. CONSPICUOUS \textsc{Than this is}.}
  2153. % FIXME: Should UCITA be mentioned anywhere in here? It was previously
  2154. % mentioned elsewhere in the tutorial but it was out of context and not
  2155. % useful. If it should be mentioned anywhere, here is probably the spot, but
  2156. % it's not clear we should mention it at all, since it's specific just to two
  2157. % state/commonwealths in the USA: MD and VA.
  2158. Critics have occasionally questioned GPL's enforceability in some jurisdictions because its
  2159. disclaimer of warranties is impermissibly broad. However,
  2160. critics
  2161. have generally failed to articulate specific precedents in their
  2162. jurisdictions that would directly indicate a problem with GPL's warranty
  2163. disclaimer. Meanwhile,
  2164. \href{http://www.cisg.law.pace.edu/cisg/text/treaty.html#35}{Article 35 of
  2165. the United Nations Convention on Contracts for the International Sale of
  2166. Goods} (often abbreviated ``CISG'', which
  2167. \href{https://treaties.un.org/Pages/ViewDetails.aspx?src=TREATY&id=228&chapter=10&lang=en}{many
  2168. countries have adopted}) permits the disclaimer of warranties, so
  2169. jurisdictions adopting this treaty allow some form of warranty
  2170. disclaimer\footnote{Scholars continue to debate to what extent CISG applies to software
  2171. licenses. For example, Diedrich concluded that ``CISG is prima facie
  2172. applicable to international transactions involving the transfer of computer
  2173. software for a price'', but Sono disagrees with this ``prevailing view'',
  2174. presenting an ``analysis [that] restricts the applicability of the CISG to
  2175. software transactions by excluding `license contracts'''. (See
  2176. \href{http://www.cisg.law.pace.edu/cisg/biblio/diedrich1.html}{Frank
  2177. Diedrich, \textit{The CISG and Computer Software Revisited}}, 6 Vindobona
  2178. Journal of International Commercial Law and Arbitration, Supplement 55--75
  2179. (2002), and
  2180. \href{http://www.cisg.law.pace.edu/cisg/biblio/sono6.html}{Hiroo Sono,
  2181. \textit{The Applicability and Non-Applicability of the CISG to Software
  2182. Transactions}}, Camilla B. Andersen \& Ulrich G. Schroeter eds., Sharing
  2183. International Commercial Law across National Boundaries: Festschrift for
  2184. Albert H. Kritzer on the Occasion of his Eightieth Birthday, Wildy, Simmonds
  2185. \& Hill Publishing (2008) 512--526.)}.
  2186. Nevertheless, to account for possible jurisdictional variances regarding this
  2187. or any other issue, GPLv2~\S11 contains
  2188. a jurisdictional savings provision, which
  2189. states that it is to be interpreted only as broadly as allowed by applicable
  2190. law. Such a provision ensures that both it, and the entire GPL, is
  2191. enforceable in any jurisdiction, regardless of any particular law regarding
  2192. the permissibility of certain warranty disclaimers.
  2193. Finally, one important point to remember when reading GPLv2~\S11 is that GPLv2~\S1
  2194. permits the sale of warranty as an additional service, which GPLv2~\S11 affirms.
  2195. \section{GPLv2~\S12: Limitation of Liability}
  2196. \label{GPLv2s12}
  2197. There are many types of warranties, and in some jurisdictions some of them
  2198. cannot be disclaimed. Therefore, usually agreements will have both a
  2199. warranty disclaimer and a limitation of liability, as we have in GPLv2~\S12.
  2200. GPLv2~\S11 thus gets rid of all implied warranties that can legally be
  2201. disavowed. GPLv2~\S12, in turn, limits the liability of the actor for any
  2202. warranties that cannot legally be disclaimed in a particular jurisdiction.
  2203. Again, some have argued the GPL is unenforceable in some jurisdictions
  2204. because its limitation of liability is impermissibly broad. However, \S
  2205. 12, just like its sister, GPLv2~\S11, contains a jurisdictional savings
  2206. provision, which states that it is to be interpreted only as broadly as
  2207. allowed by applicable law. As stated above, such a provision ensures that
  2208. both GPLv2~\S12, and the entire GPL, is enforceable in any jurisdiction,
  2209. regardless of any particular law regarding the permissibility of limiting
  2210. liability.
  2211. So end the terms and conditions of the GNU General Public License.
  2212. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  2213. \chapter{GPL Version 3}
  2214. \label{GPLv3}
  2215. This chapter discusses the text of GPLv3. Much of this material herein
  2216. includes text that was adapted (with permission) from text that FSF
  2217. originally published as part of the so-called ``rationale documents'' for the
  2218. various discussion drafts of GPLv3.
  2219. The FSF ran a somewhat public process to develop GPLv3, and it was the first
  2220. attempt of its kind to develop a Free Software license this way. Ultimately,
  2221. RMS was the primary author of GPLv3, but he listened to feedback from all
  2222. sorts of individuals and even for-profit companies. Nevertheless, in
  2223. attempting to understand GPLv3 after the fact, the materials available from
  2224. the GPLv3 process have a somewhat ``drinking from the firehose'' effect.
  2225. This chapter seeks to explain GPLv3 to newcomers, who perhaps are familiar
  2226. with GPLv2 and who did not participate in the GPLv3 process.
  2227. Those who wish to drink from the firehose and take a diachronic approach to
  2228. GPLv3 study by reading the step-by-step public drafting process of the GPLv3 (which
  2229. occurred from Monday 16 January 2006 through Monday 19 November 2007) should
  2230. visit \url{http://gplv3.fsf.org/}.
  2231. \section{Understanding GPLv3 As An Upgraded GPLv2}
  2232. Ultimately, GPLv2 and GPLv3 co-exist as active licenses in regular use. As
  2233. discussed in Chapter~\ref{tale-of-two-copylefts}, GPLv1 was never regularly
  2234. used alongside GPLv2. However, given GPLv2's widespread popularity and
  2235. existing longevity by the time GPLv3 was published, it is not surprising that
  2236. some licensors still prefer GPLv2-only or GPLv2-or-later. GPLv3 gained major
  2237. adoption by many projects, old and new, but many projects have not upgraded
  2238. due to (in some cases) mere laziness and (in other cases) policy preference
  2239. for some of GPLv2's terms and/or policy opposition to GPLv3's terms.
  2240. Given this ``two GPLs world'' is reality, it makes sense to consider GPLv3 in
  2241. terms of how it differs from GPLv2. Also, most of the best GPL experts in
  2242. the world must deal regularly with both licenses, and admittedly have decades
  2243. of experience with GPLv2 while the most experience with GPLv3 that's possible
  2244. is by definition less than a decade. These two factors usually cause even new
  2245. students of GPL to start with GPLv2 and move on to GPLv3, and this tutorial
  2246. follows that pattern.
  2247. Overall, the changes made in GPLv3 admittedly \textit{increased} the
  2248. complexity of the license. The FSF stated at the start of the GPLv3 process
  2249. that they would have liked to oblige those who have asked for a simpler and
  2250. shorter GPL\@. Ultimately, the FSF gave priority to making GPLv3 a better
  2251. copyleft license in the spirit of past GPL's. Obsession for concision should
  2252. never trump software freedom.
  2253. The FSF had many different, important goals in seeking to upgrade to GPLv3.
  2254. However, one important goal that is often lost in the discussion of policy
  2255. minutia is a rather simple but important issue. Namely, FSF sought to assure
  2256. that GPLv3 was more easily internationalized than GPLv2. In particular, the
  2257. FSF sought to ease interpretation of GPL in other countries by replacement of
  2258. USA-centric\footnote{See Section~\ref{non-usa-copyright} of this tutorial for
  2259. a brief discussion about non-USA copyright systems.} copyright phrases and
  2260. wording with neutral terminology rooted in description of behavior rather
  2261. than specific statute. As can be seen in the section-by-section discussion of
  2262. GPLv3 that follows, nearly every section had changes related to issues of
  2263. internationalization.
  2264. \section{GPLv3~\S0: Giving In On ``Defined Terms''}
  2265. \label{GPLv3s0}
  2266. One of lawyers' most common complaints about GPLv2 is that defined terms in
  2267. the document appear throughout. Most licenses define terms up-front.
  2268. However, the GPL was always designed both as a document that should be easily
  2269. understood both by lawyers and by software developers: it is a document
  2270. designed to give freedom to software developers and users, and therefore it
  2271. should be comprehensible to that constituency.
  2272. Interestingly enough, one coauthor of this tutorial who is both a lawyer and
  2273. a developer pointed out that in law school, she understood defined terms more
  2274. quickly than other law students precisely because of her programming
  2275. background. For developers, having \verb0#define0 (in the C programming
  2276. language) or other types of constants and/or macros that automatically expand
  2277. in the place where they are used is second nature. As such, adding a defined
  2278. terms section was not terribly problematic for developers, and thus GPLv3
  2279. adds one. Most of these defined terms are somewhat straightforward and bring
  2280. forward better worded definitions from GPLv2. Herein, this tutorial
  2281. discusses a few of the new ones.
  2282. GPLv3~\S0 includes definitions of five new terms not found in any form in
  2283. GPLv2: ``modify'' ``covered work'', ``propagate'', ``convey'', and
  2284. ``Appropriate Legal Notices''.
  2285. \subsection{Modify and the Work Based on the Program}
  2286. % FIXME: I think we actually need to research the claim below that
  2287. % ``derivative work'' as a term is unique to USA copyright law. I have
  2288. % heard German lawyers, for example, use the term extensively. Is it also a
  2289. % term perhaps under German law? -- bkuhn
  2290. GPLv2 included a defined term, ``work based on the Program'', but also used
  2291. the term ``modify'' and ``based on'' throughout the license. GPLv2's ``work
  2292. based on the Program'' definition made use of a legal term of art,
  2293. ``derivative work'', which is peculiar to USA copyright
  2294. law.\footnote{Ironically, most criticism of USA-specific legal
  2295. terminology in GPLv2's ``work based on the Program'' definition historically
  2296. came not primarily from readers outside the USA, but from those within
  2297. it. The FSF noted in that it did not generally agree with these
  2298. views, and expressed puzzlement by the energy with which they were
  2299. expressed, given the existence of many other, more difficult legal issues
  2300. implicated by the GPL. Nevertheless, the FSF argued that it made sense to
  2301. eliminate usage of local copyright terminology to good effect.} GPLv2
  2302. always sought to cover all rights governed by relevant copyright law, in the
  2303. USA and elsewhere.
  2304. Even though differently-labeled concepts corresponding to the
  2305. derivative work are recognized in all copyright law systems, these
  2306. counterpart concepts might differ to some degree in scope and breadth from
  2307. the USA derivative work. GPLv3 therefore internationalizes
  2308. on this issue by removing GPLv2's references to derivative
  2309. works and by providing a more globally useful definition.
  2310. GPLv3 drops all reference to USA ``derivative works'' and returns
  2311. to the base concept only: GPL covers the licensed work and all works where
  2312. copyright permission from the licensed work's copyright holder.
  2313. The new definitions returns to the common elements of copyright law. Copyright
  2314. holders of works of software have the exclusive right to form new works by
  2315. modification of the original --- a right that may be expressed in various
  2316. ways in different legal systems. GPLv3 operates to grant this right to
  2317. successive generations of users (particularly through the copyleft conditions
  2318. set forth in GPLv3~\S5, as described later in this tutorial in its
  2319. \S~\ref{GPLv3s5}). Here in GPLv3~\S0, ``modify'' refers to basic copyright
  2320. rights, and then this definition of ``modify'' is used to define ``modified
  2321. version of'' and ``work based on'' as synonyms.
  2322. \subsection{The Covered Work}
  2323. GPLv3 uses a common license drafting technique of building upon simpler
  2324. definitions to make complex ones. The Program is a defined term found
  2325. throughout GPLv2, and the word ``covered'' and the phrase ``covered by this
  2326. license'' are used in tandem with the Program in GPLv2, but not as part of a
  2327. definition. GPLv3 offers a single term ``covered work'', which enables some
  2328. of the wording in GPLv3 to be simpler and clearer than its GPLv2
  2329. counterparts.
  2330. Next, to avoid locking GPLv3 into specific copyright statues, the GPLv3
  2331. defines two terms that are otherwise exotic to the language of international
  2332. copyright.
  2333. \subsection{Propagate}
  2334. To ``propagate'' a work covered by the license means any activity in a locale
  2335. that requires permission of copyright holders in that locale's legal system.
  2336. However, personal use or modification for personal use are activities explicitly
  2337. excluded from ``propagation'' \textit{regardless} of domestic copyright law.
  2338. The term ``propagate'' serves two purposes. First, ``propagate'' provides a
  2339. simple and convenient means for distinguishing between the kinds of uses of a
  2340. work that GPL imposes conditions on and the kinds of uses that GPL does not
  2341. (for the most part) impose conditions on.
  2342. Second, ``propagate'' helps globalize GPL in its wording and effect:
  2343. ``derivative work'' was in fact not the only term commonly used by local
  2344. copyright statutes. A term like ``distribute'' (or its equivalent in
  2345. languages other than English) is also used in several national copyright
  2346. statutes. Practical experience with GPLv2 revealed the awkwardness of using
  2347. the term ``distribution'' in a license intended for global use: the scope of
  2348. ``distribution'' in the copyright context can differ from country to country.
  2349. The GPL never necessarily intended the specific meaning of ``distribution''
  2350. that exists under USA (or any other country's) copyright law.
  2351. Indeed, even within a single country and language, the term distribution may
  2352. be ambiguous; as a legal term of art, distribution varies significantly in
  2353. meaning among those countries that recognize it. For example, comments
  2354. during GPLv3's drafting process indicated that in at least one country,
  2355. distribution may not include network transfers of software but may include
  2356. interdepartmental transfers of physical copies within an organization.
  2357. Meanwhile, the copyright laws of many countries, as well as certain
  2358. international copyright treaties, recognize ``making available to the
  2359. public'' or ``communication to the public'' as one of the exclusive rights of
  2360. copyright holders.
  2361. Therefore, the GPLv3 defines the term ``propagate'' by reference to activities
  2362. that require permission under ``applicable copyright law'', but excludes
  2363. execution and private modification from the definition. GPLv3's definition
  2364. also gives examples of activities that may be included within ``propagation''
  2365. but it also makes clear that, under the copyright laws of a given country,
  2366. ``propagation'' may include other activities as well.
  2367. Thus, propagation is defined by behavior, and not by categories drawn from
  2368. some particular national copyright statute. This helps not only with
  2369. internationalization, but also factually-based terminology aids in
  2370. developers' and users' understanding of the GPL\@.
  2371. As a further benefit, because ``propagation'' includes all
  2372. exclusive rights granted under any particular copyright regime, the term
  2373. automatically accounts for all exclusive rights under that regime.
  2374. \subsection{Convey}
  2375. Next, GPLv3 defines a subset of propagate --- ``convey''.
  2376. Conveying includes activities that constitute propagation of copies to
  2377. others. As with the definition of propagate, GPLv3 thus addresses transfers
  2378. of copies of software in behavioral rather than statutory terms.
  2379. Any propagation that enables other parties to receive or make copies of the
  2380. work, is called ``conveying''. Usually, conveying is the activity that
  2381. triggers most of the other obligations of GPLv3.
  2382. \subsection{Appropriate Legal Notices}
  2383. GPLv2 used the term ``appropriate copyright notice and disclaimer of
  2384. warranty'' in two places, which is a rather bulky term. Also, experience with
  2385. GPLv2 and other licenses that grant software freedom showed throughout the
  2386. 1990s that the scope of types of notices that need preservation upon
  2387. conveyance were more broad that merely the copyright notices. The
  2388. Appropriate Legal Notice definition consolidates the material that GPLv2
  2389. traditionally required preserved into one definition.
  2390. \subsection{Other Defined Terms}
  2391. Note finally that not all defined terms in GPLv3 appear in GPLv3~\S0.
  2392. Specifically, those defined terms that are confined in use to a single
  2393. section are defined in the section in which they are used, and GPLv3~\S1
  2394. contains those definitions focused on source code. In this tutorial, those
  2395. defined terms are discussed in the section where they are defined and/or
  2396. used.
  2397. \section{GPLv3~\S1: Understanding CCS}
  2398. \label{GPLv3s1}
  2399. Ensuring that users have the source code to the software they receive and the
  2400. freedom to modify remains the paramount right embodied in the Free Software
  2401. Definition (found in \S~\ref{Free Software Definition} of this tutorial). As
  2402. such, GPLv3~\S1 is likely one of the most important sections of GPLv3, as it
  2403. contains all the defined terms related to this important software freedom.
  2404. \subsection{Source Code Definition}
  2405. First, GPLv3~\S1 retains GPLv2's definition of ``source code'' and adds an
  2406. explicit definition of ``object code'' as ``any non-source version of a
  2407. work''. Object code is not restricted to a narrow technical meaning and is
  2408. understood broadly to include any form of the work other than the preferred
  2409. form for making modifications to it. Object code therefore includes any kind
  2410. of transformed version of source code, such as bytecode or minified
  2411. Javascript. The definition of object code also ensures that licensees cannot
  2412. escape their obligations under the GPL by resorting to shrouded source or
  2413. obfuscated programming.
  2414. \subsection{CCS Definition}
  2415. \label{CCS Definition}
  2416. The definition of CCS,\footnote{Note that the preferred term for those who
  2417. work regularly with both GPLv2 and GPLv3 is ``Complete Corresponding
  2418. Source'', abbreviated to ``CCS''. Admittedly, the word ``complete'' no
  2419. longer appears in GPLv3 (which uses the word ``all'' instead). However,
  2420. both GPLv2 and the early drafts of GPLv3 itself used the word ``complete'',
  2421. and early GPLv3 drafts even called this defined term ``Complete
  2422. Corresponding Source''. Meanwhile, use of the acronym ``CCS'' (sometimes,
  2423. ``C\&CS'') was so widespread among GPL enforcers that its use continues
  2424. even though GPLv3-focused experts tend to say just the defined term of
  2425. ``Corresponding Source''.} or, as GPLv3 officially calls it,
  2426. ``Corresponding Source'' in GPLv3~\S1\P4 is possibly the most complex
  2427. definition in the license.
  2428. The CCS definition is broad so as to protect users' exercise of their rights
  2429. under the GPL\@. The definition includes particular examples to remove
  2430. any doubt that they are to be considered CCS\@. GPLv3 seeks to make it
  2431. completely clear that a licensee cannot avoid complying with the requirements
  2432. of the GPL by dynamically linking a subprogram component to the original
  2433. version of a program. The examples also clarify that the shared libraries
  2434. and dynamically linked subprograms that are included in Corresponding Source
  2435. are those that the work is ``specifically'' designed to require, which
  2436. clarifies that they do not include libraries invoked by the work that can be
  2437. readily substituted by other existing implementations. While copyleft
  2438. advocates never doubted this was required under GPLv2's definition of CCS,
  2439. GPLv3 makes it abundantly clear with an extra example.
  2440. The GPL, as always, seeks to ensure users are truly in a position to install and
  2441. run their modified versions of the program; the CCS definition is designed to
  2442. be expansive to ensure this software freedom. However, although the
  2443. definition of CCS is expansive, it is not sufficient to protect users'
  2444. freedoms in many circumstances. For example, a GPL'd program, or a modified
  2445. version of such a program, might be locked-down and restricted. The
  2446. requirements in GPLv3~\S6 (discussed in Section~\ref{GPLv3s6} of this
  2447. tutorial) handle that issue. (Early drafts of GPLv3 included those
  2448. requirements in the definition of CCS; however, given that the lock-down
  2449. issue only comes up in distribution of object code, it is more logical to
  2450. place those requirements with the parts of GPLv3 dealing directly with object
  2451. code distribution).
  2452. The penultimate paragraph in GPLv3\S2 notes that GPLv3's CCS definition does
  2453. not require source that can be automatically generated. Many code
  2454. generators, preprocessors and take source code as input and sometimes even
  2455. have output that is still source code. Source code should always be whatever
  2456. the original programmer preferred to modify.
  2457. GPLv3\S1's final paragraph removes any ambiguity about what should be done on
  2458. source-only distributions. Specifically, the right to convey source code
  2459. that does not compile, does not work, or otherwise is experimental
  2460. in-progress work is fully permitted, \textit{provided that} no object code
  2461. form is conveyed as well. Indeed, when combined with the permissions in
  2462. GPLv3\S~5, it is clear that if one conveys \textit{only} source code, one can
  2463. never be required to provide more than that. One always has the right to
  2464. modify a source code work by deleting any part of it, and there can be no
  2465. requirement that free software source code be a whole functioning program.
  2466. \subsection{The System Library Exception}
  2467. \label{GPLv3-system-library-exception}
  2468. The previous section skipped over one part of the CCS definition, the
  2469. so-called system library exception. The ``System Libraries'' definition (and
  2470. the ``Standard Interface'' and ``Major Component'' definitions, which it
  2471. includes) are designed
  2472. to permit certain distribution arrangements that are considered reasonable by
  2473. copyleft advocates. The system library exception is designed to allow
  2474. copylefted software to link with these libraries when prohibition of that linking would hurt
  2475. software freedom more than it would hurt proprietary software.
  2476. The system library exception has two parts. Part (a) rewords the GPLv2
  2477. exception for clarity replacing GPLv2's words ``unless that component itself
  2478. accompanies the executable'' with ``which is not part of the Major
  2479. Component''. The goal here is to not require disclosure of source code of
  2480. certain libraries, such as necessary Microsoft Windows DLLs (which aren't
  2481. part of Windows' kernel but accompany it) that are required for functioning
  2482. of copylefted programs compiled for Windows.
  2483. However, in isolation, (a) would be too permissive, as it would sometimes
  2484. allow distributors to evade important GPL requirements. Part (b) reigns
  2485. in (a). Specifically, (b) specifies only a few functionalities that a
  2486. system library may provide and still qualify for the exception. The goal is
  2487. to ensure system libraries are truly adjunct to a major essential operating
  2488. system component, compiler, or interpreter. The more low-level the
  2489. functionality provided by the library, the more likely it is to be qualified
  2490. for this exception.
  2491. Admittedly, the system library exception is a frequently discussed topic of
  2492. obsessed GPL theorists. The amount that has been written on the system
  2493. library exception (both the GPLv2 and GPLv3 versions of it), if included
  2494. herein, could easily increase this section of the tutorial to a length
  2495. greater than all the others.
  2496. Like any exception to the copyleft requirements of GPL, would-be GPL
  2497. violators frequently look to the system library exception as a potential
  2498. software freedom circumvention technique. When considering whether or not a
  2499. library qualifies for the system library exception, here is a pragmatic
  2500. thesis to consider, based on the combined decades of experience in GPL
  2501. interpretation of this tutorial's authors: the harder and more strained the
  2502. reader must study and read the system library exception, the more likely it
  2503. is that the library in question does not qualify for it.
  2504. \section{GPLv3~\S2: Basic Permissions}
  2505. \label{GPLv3S2}
  2506. GPLv3~\S2 can roughly be considered as an equivalent to GPLv2~\S0 (discussed
  2507. in \S~\ref{GPLv2s0} of this tutorial). However, the usual style of
  2508. improvements found in GPLv3 are found here as well. For example, the first
  2509. sentence of GPLv3~\S2 furthers the goal internationalization. Under the
  2510. copyright laws of some countries, it may be necessary for a copyright license
  2511. to include an explicit provision setting forth the duration of the rights
  2512. being granted. In other countries, including the USA, such a provision is
  2513. unnecessary but permissible.
  2514. GPLv3~\S2\P1 also acknowledges that licensees under the GPL enjoy rights of
  2515. copyright fair use, or the equivalent under applicable law. These rights are
  2516. compatible with, and not in conflict with, the freedoms that the GPL seeks to
  2517. protect, and the GPL cannot and should not restrict them.
  2518. However, note that (sadly to some copyleft advocates) the unlimited freedom
  2519. to run is confined to the \textit{unmodified} Program. This confinement is
  2520. unfortunately necessary since Programs that do not qualify as a User Product
  2521. in GPLv3~\S6 (see \S~\ref{user-product} in this tutorial) might have certain
  2522. unfortunate restrictions on the freedom to run.\footnote{See
  2523. \S~\ref{freedom-to-run} of this tutorial for the details on ``the freedom to
  2524. run''.}
  2525. GPLv3~\S2\P2 distinguishes between activities of a licensee that are
  2526. permitted without limitation and activities that trigger additional
  2527. requirements. Specifically, GPLv3~\S2\P2 guarantees the basic freedoms of
  2528. privately modifying and running the program. While these basic freedoms were
  2529. generally considered a standard part of users' rights under GPLv2 as well,
  2530. the GPLv3 states them herein more explicitly. In other words, there is no
  2531. direct analog to the first sentence of GPLv3~\S2\P2 in GPLv2
  2532. (See \S~\ref{gplv2-private-modification} of this tutorial for more on this issue.)
  2533. Also, GPLv3~\S2\P2 gives an explicit permission for a client to provide a
  2534. copy of its modified software to a contractor exclusively for that contractor
  2535. to modify it further, or run it, on behalf of the client. However, the
  2536. client can \textit{only} exercise this control over its own copyrighted
  2537. changes to the GPL-covered program. The parts of the program it obtained
  2538. from other contributors must be provided to the contractor with the usual GPL
  2539. freedoms. Thus, GPLv3 permits users to convey covered works to contractors
  2540. operating exclusively on the users' behalf, under the users' direction and
  2541. control, and to require the contractors to keep the users' copyrighted
  2542. changes confidential, but \textit{only if} the contractor is limited to acting
  2543. on the users' behalf (just as the users' employees would have to act).
  2544. The strict conditions in this ``contractors provision'' are needed so that it
  2545. cannot be twisted to fit other activities, such as making a program available
  2546. to downstream users or customers. By making the limits on this provision
  2547. very narrow, GPLv3 ensures that, in all other cases, contractor gets the
  2548. full freedoms of the GPL that they deserve.
  2549. The FSF was specifically asked to add this ``contractors provisions'' by
  2550. large enterprise users of Free Software, who often contract with non-employee
  2551. developers, working offsite, to make modifications intended for the user's
  2552. private or internal use, and often arrange with other companies to operate
  2553. their data centers. Whether GPLv2 permits these activities is not clear and
  2554. may depend on variations in copyright law in different jurisdictions. The
  2555. practices seem basically harmless, so FSF decided to make it clear they are
  2556. permitted.
  2557. GPLv3~\S2's final paragraph includes an explicit prohibition of sublicensing.
  2558. This provision ensures that GPL enforcement is always by the copyright
  2559. holder. Usually, sublicensing is regarded as a practical convenience or
  2560. necessity for the licensee, to avoid having to negotiate a license with each
  2561. licensor in a chain of distribution. The GPL solves this problem in another
  2562. way --- through its automatic licensing provision found in GPLv3~\S10 (which
  2563. is discussed in more detail in \S~\ref{GPLv3s10} of this tutorial).
  2564. \section{GPLv3's views on DRM and Device Lock-Down}
  2565. \label{GPLv3-drm}
  2566. The issues of DRM, device lock-down and encryption key disclosure were the
  2567. most hotly debated during the GPLv3 process. FSF's views on this were sadly
  2568. frequently misunderstood and, comparing the provisions related to these
  2569. issues in the earliest drafts of GPLv3 to the final version of GPLv3 shows
  2570. the FSF's willingness to compromise on tactical issues to reach the larger
  2571. goal of software freedom.
  2572. Specifically, GPLv3 introduced provisions that respond to the growing
  2573. practice of distributing GPL-covered programs in devices that employ
  2574. technical means to restrict users from installing and running modified
  2575. versions. This practice thwarts the expectations of developers and users
  2576. alike, because the right to modify is one of the core freedoms the GPL is
  2577. designed to secure.
  2578. Technological measures to defeat users' rights. These measures are often
  2579. described by such Orwellian phrases, such as ``digital rights management,''
  2580. which actually means limitation or outright destruction of users' legal
  2581. rights, or ``trusted computing,'' which actually means selling people
  2582. computers they cannot trust. However, these measures are alike in one basic
  2583. respect. They all employ technical means to turn the system of copyright law
  2584. (where the powers of the copyright holder are limited exceptions to general
  2585. freedom) into a virtual prison, where everything not specifically permitted
  2586. is utterly forbidden. This system of ``para-copyright'' was created well
  2587. after GPLv2 was written --- initially through legislation in the USA and the
  2588. EU, and later in other jurisdictions as well. This legislation creates
  2589. serious civil or even criminal penalties to escape from these restrictions
  2590. (commonly and aptly called ``jail-breaking a device''), even where the
  2591. purpose in doing so is to restore the users' legal rights that the technology
  2592. wrongfully prevents them from exercising.
  2593. GPLv2 did not address the use of technical measures to take back the rights
  2594. that the GPL granted, because such measures did not exist in 1991, and would
  2595. have been irrelevant to the forms in which software was then delivered to
  2596. users. GPLv3 addresses these issues, particularly because copylefted
  2597. software is ever more widely embedded in devices that impose technical
  2598. limitations on the user's freedom to change it.
  2599. However, FSF always made a clear distinction to avoid conflating these
  2600. ``lock-down'' measures with legitimate applications that give users control,
  2601. as by enabling them to choose higher levels of system or data security within
  2602. their networks, or by allowing them to protect the security of their
  2603. communications using keys they can generate or copy to other devices for
  2604. sending or receiving messages. Such technologies present no obstacles to
  2605. software freedom and the goals of copyleft.
  2606. The public GPLv3 drafting process sought to balance these positions of
  2607. copyleft advocates with various disparate views of the larger
  2608. Free-Software-using community. Ultimately, FSF compromised to the GPLv3\S3
  2609. and GPLv3\S6 provisions that, taken together, are a minimalist set of terms
  2610. sufficient to protect the software freedom against the threat of invasive
  2611. para-copyright.
  2612. The compromises made were ultimately quite reasonable. The primary one is
  2613. embodied in GPLv3\S6's ``User Product'' definition (see \S~\ref{user-product}
  2614. in this tutorial for details). Additionally, some readers of early GPLv3
  2615. drafts seem to have assumed GPLv3 contained a blanket prohibition on DRM; but
  2616. it does not. In fact, no part of GPLv3 forbids DRM regarding non-GPL'd
  2617. works; rather, GPLv3 forbids the use of DRM specifically to lock-down
  2618. restrictions on users' ability to install modified versions of the GPL'd
  2619. software itself, but again, \textit{only} with regard to User Products.
  2620. \section{GPLv3~\S3: What Hath DMCA Wrought}
  2621. \label{GPLv3s3}
  2622. As discussed in \S~\ref{software-and-non-copyright} of this tutorial,
  2623. \href{http://www.law.cornell.edu/uscode/text/17/1201}{17 USC~\S1201} and
  2624. related sections\footnote{These sections of the USC are often referred to as
  2625. the ``Digital Millennium Copyright Act'', or ``DMCA'', as that was the name
  2626. of the bill that so-modified these sections of the USC\@.} prohibits users
  2627. from circumventing technological measures that implement DRM\@. Since this
  2628. is part of copyright law and the GPL is primarily a copyright license, and
  2629. since what the DMCA calls ``circumvention'' is simply ``modifying the
  2630. software'' under the GPL, GPLv3 must disclaim that such anti-circumvention
  2631. provisions are not applicable to the GPLv3'd software. GPLv3\S3 shields
  2632. users from being subjected to liability under anti-circumvention law for
  2633. exercising their rights under the GPL, so far as the GPL can do so.
  2634. First, GPLv3\S3\P1 declares that no GPL'd program is part of an effective
  2635. technological protection measure, regardless of what the program does. Early
  2636. drafts of GPLv3\S3\P1 referred directly to the DMCA, but the final version
  2637. instead includes instead an international legal reference to
  2638. anticircumvention laws enacted pursuant to the 1996 WIPO treaty and any
  2639. similar laws. Lawyers outside the USA worried that a USA statutory reference
  2640. could be read as indicating a choice for application of USA law to the
  2641. license as a whole. While the FSF did not necessarily agree with that view,
  2642. the FSF decided anyway to refer to the WIPO treaty rather than DMCA, since
  2643. several national anticircumvention laws were (or will likely be) structured
  2644. more similarly to the anticircumvention provisions of the DMCA in their
  2645. implementation of WIPO\@. Furthermore, the addition of ``or similar laws''
  2646. provides an appropriate catch-all.
  2647. GPLv3\S3\P2 states precisely that a conveying party waives the
  2648. power to forbid circumvention of technological measures only to the extent
  2649. that such circumvention is accomplished through the exercise of GPL rights in
  2650. the conveyed work. GPLv3\S3\P2 makes clear that the referenced ``legal
  2651. rights'' are specifically rights arising under anticircumvention law. and
  2652. refers to both the conveying party's rights and to third party rights, as in
  2653. some cases the conveying party will also be the party legally empowered to
  2654. enforce or invoke rights arising under anticircumvention law.
  2655. These disclaimers by each licensor of any intention to use GPL'd software to
  2656. stringently control access to other copyrighted works should effectively
  2657. prevent any private or public parties from invoking DMCA-like laws against
  2658. users who escape technical restriction measures implemented by GPL'd
  2659. software.
  2660. \section{GPLv3~\S4: Verbatim Copying}
  2661. \label{GPLv3s4}
  2662. GPLv3~\S4 is a revision of GPLv2~\S1 (as discussed in \S~\ref{GPLv2s1} of
  2663. this tutorial). There are almost no changes to this section from the
  2664. GPLv2~\S1, other than to use the new defined terms.
  2665. The only notable change, of ``a fee'' to ``any price or no price'', is in the
  2666. first sentence of GPLv3\S4\P2. The GPLv2\S1\P1 means that the GPL permits
  2667. one to charge money for the distribution of software. Despite efforts by
  2668. copyleft advocates to explain this in GPLv2 itself and in other documents,
  2669. there are evidently some people who still believe that GPLv2 allows charging
  2670. for services but not for selling copies of software and/or that the GPL
  2671. requires downloads to be gratis. Perhaps this is because GPLv2 referred to
  2672. charging a ``fee''; the term ``fee'' is generally used in connection with
  2673. services.
  2674. GPLv2's wording also referred to ``the physical act of transferring.'' The
  2675. intention was to distinguish charging for transfers from attempts to impose
  2676. licensing fees on all third parties. ``Physical'' might be read, however, as
  2677. suggesting ``distribution in a physical medium only''.
  2678. To address these two issues, GPLv3 says ``price'' in place of ``fee,'' and
  2679. removes the term ``physical.''
  2680. GPLv3~\S4 has also been revised from its corresponding section in GPLv2 in
  2681. light of the GPLv3~\S7 (see \S~\ref{GPLv3s7} in this tutorial for more).
  2682. Specifically, a distributor of verbatim copies of the program's source code
  2683. must obey any existing additional terms that apply to parts of the program
  2684. pursuant to GPLv3~\S7. In addition, the distributor is required to keep
  2685. intact all license notices, including notices of such additional terms.
  2686. Finally, there is no harm in explicitly pointing out what ought to be
  2687. obvious: that those who convey GPL-covered software may offer commercial
  2688. services for the support of that software.
  2689. \section{GPLv3~\S5: Modified Source}
  2690. \label{GPLv3s5}
  2691. GPLv3\S5 is the rewrite of GPLv2\S2, which was discussed in \S~\ref{GPLv2s2}
  2692. of this tutorial. This section discusses the changes found in GPLv3\S5
  2693. compared to GPLv2\S2.
  2694. GPLv3\S5(a) still requires modified versions be marked with ``relevant
  2695. date'', but no longer says ``the date of any change''. The best practice is
  2696. to include the date of the latest and/or most significant changes and who
  2697. made those. Of course, compared to its GPLv2\S2(a), GPLv3\S5(a) slightly
  2698. relaxes the requirements regarding notice of changes to the program. In
  2699. particular, the modified files themselves need no longer be marked. This
  2700. reduces administrative burdens for developers of modified versions of GPL'd
  2701. software.
  2702. GPLv3\S5(b) is a new but simple provision. GPLv3\S5(b) requires that the
  2703. license text itself must be unmodified (except as permitted by GPLv3\S7; see
  2704. \S~\ref{GPLv3s7} in this tutorial). Furthermore, it removes any perceived
  2705. conflict between the words ``keep intact all notices'' in GPLv3\S4, since
  2706. operating under GPLv3\S5 still includes all the requirements of GPLv3\S4 by
  2707. reference.
  2708. GPLv3\S5(c) is the primary source-code-related copyleft provision of GPL. (The
  2709. object-code-related copyleft provisions are in GPLv3\S6, discussed in
  2710. \S~\ref{GPLv3s6} of this tutorial). Compared to GPLv2\S2(b), GPLv3\S5(c)
  2711. states that the GPL applies to the whole of the work. Such was stated
  2712. already in GPLv2\S2(b), in ``in whole or in part'', but this simplified
  2713. wording makes it clear it applies to the entire covered work.
  2714. Another change in GPLv3\S5(c) is the removal of the
  2715. words ``at no charge,'' which was often is misunderstood upon na\"{i}ve
  2716. reading of in GPLv2\S(b) (as discussed in \S~\ref{GPLv2s2-at-no-charge} of this
  2717. tutorial).
  2718. % FIXME-LATER: Write up something on 5d, and related it to Appropriate Legal Notices.
  2719. Note that of GPLv2~\S2's penultimate and ante-penultimate paragraphs are now
  2720. handled adequately by the definitions in GPLv3\S0 and as such, have no direct
  2721. analogs in GPLv3.
  2722. GPLv2~\S2's final paragraph, however, is reworded and expanded into the final
  2723. paragraph of GPLv3\S5, which now also covers issues related to copyright
  2724. compilations (but not compilations into object code --- that's in the next
  2725. section!). The intent and scope is the same as was intended in GPLv2.
  2726. \section{GPLv3~\S6: Non-Source and Corresponding Source}
  2727. \label{GPLv3s6}
  2728. GPLv3~\S6 states the compliance obligations for distributing ``non-source
  2729. forms'' of a program (which means any form other than CCS). As noted in \S~\ref{GPLv3s0}, ``object code'' in GPLv3
  2730. is defined broadly to mean any non-source version of a work, and thus
  2731. includes not only binaries or executables, but also obfuscated, minimized, compressed or otherwise
  2732. non-preferred forms for modification. Thus, GPLv3~\S6 clarifies and revises GPLv2~\S3.
  2733. Indeed, GPLv3~\S6's CCS requirement under
  2734. closely parallels the provisions of \hyperref[GPLv2s3]{GPLv2~\S3}, with changes
  2735. designed to make compliant provisioning easier under contemporary
  2736. technological conditions. Distributors of GPLv3'd
  2737. object code must provide access to the corresponding source code, in one of
  2738. four specified ways.
  2739. % FIXME: probably mostly still right, needs some updates, though.
  2740. GPLv3~\S6(a--b) now apply specifically to distribution of object code in a
  2741. physical product. Physical products include embedded systems, as well as
  2742. physical software distribution media such as CDs. As in GPLv2~\S3 (discussed
  2743. in \S~\ref{GPLv2s3} of this tutorial), the distribution of object code may
  2744. either be accompanied by the machine-readable source code, or it may be
  2745. accompanied by a valid written offer to provide the machine-readable source
  2746. code. However, unlike in GPLv2, that offer cannot be exercised by any third
  2747. party; rather, only those ``who possess the object code'' can exercise
  2748. the offer. (Note that this is a substantial narrowing of requirements of
  2749. offer fulfillment, and is a wonderful counterexample to dispute claims that
  2750. the GPLv3 has more requirements than GPLv2.)
  2751. % FIXME: probably mostly still right, needs some updates, though.
  2752. GPLv3~\S6(b) further revises the requirements for the written offer to
  2753. provide source code. As before, the offer must remain valid for at least
  2754. three years. In addition, even after three years, a distributor of a product
  2755. containing GPL'd object code must offer to provide source code for as long as
  2756. the distributor also continues to offer spare parts or customer support for
  2757. the product model. This is a reasonable and appropriate requirement; a
  2758. distributor should be prepared to provide source code if he or she is
  2759. prepared to provide support for other aspects of a physical product.
  2760. GPLv3~\S6(a--b) clarifies that the medium for software interchange on which
  2761. the machine-readable source code is provided must be a durable physical
  2762. medium. GPLv3~\S6(b)(2), however, permits a distributor to instead offer to
  2763. provide source code from a network server instead, which is yet another
  2764. example GPLv3 looser in its requirements than GPLv2 (see
  2765. \S~\ref{GPLv2s3-medium-customarily} for details).
  2766. % FIXME-LATER: more information about source provision, cost of physically
  2767. % performing, reasonable fees, medium customary clearly being said durable
  2768. % connecting back to previous text
  2769. GPLv3\S6(c) gives narrower permission than GPLv2\S3(c). The ``pass along''
  2770. option for GPLv3\S6(c)(1) offers is now available only for individual
  2771. distribution of object code; moreover, such individual distribution can occur
  2772. only ``occasionally and noncommercially.'' A distributor cannot comply with
  2773. the GPL merely by making object code available on a publicly-accessible
  2774. network server accompanied by a copy of the written offer to provide source
  2775. code received from an upstream distributor.
  2776. %FIXME-LATER: tie back to the discussion of the occasional offer pass along
  2777. % stuff in GPLv2 this tutorial.
  2778. GPLv3~\S6(d) revises and improves GPLv2~\S3's final paragraph. When object
  2779. code is provided by offering access to copy the code from a designated place
  2780. (such as by enabling electronic access to a network server), the distributor
  2781. must merely offer equivalent access to copy the source code ``in the same way
  2782. through the same place''. This wording also permits a distributor to offer a
  2783. third party access to both object code and source code on a single network
  2784. portal or web page, even though the access may include links to different
  2785. physical servers. For example, a downstream distributor may provide a link
  2786. to an upstream distributor's server and arrange with the operator of that
  2787. server to keep the source code available for copying for as long as the
  2788. downstream distributor enables access to the object code. Thus,
  2789. the obligation remains on the party distributing object code to point
  2790. prominently (``next to'' the object code download) to the third-party source
  2791. code provisioning server, and to ensure that this third-party server remains
  2792. in operation for required period. This codifies formally the typical
  2793. historical interpretation of GPLv2.
  2794. % FIXME-LATER: perhaps in enforcement section, but maybe here, note about
  2795. % ``slow down'' on source downloads being a compliance problem.
  2796. Furthermore, under GPLv3~\S6(d), distributors may charge for the conveyed
  2797. object code; however, those who pay to obtain the object code must be given
  2798. equivalent and gratis access to obtain the CCS. (If distributors convey the
  2799. object code gratis, distributors must likewise make CCS available without
  2800. charge.) Those who do not obtain the object code from that distributors
  2801. (perhaps because they choose not to pay the fee for object code) are outside
  2802. the scope of the provision; distributors are under no specific obligation to
  2803. give CCS to someone who has not purchased an object code download under
  2804. GPLv3~\S6(d). (Note: this does not change nor impact any obligations under
  2805. GPLv3~\S6(b)(2); GPLv3~\S6(d) is a wholly different provision.)
  2806. \subsection{GPLv3~\S6(e): Peer-to-Peer Sharing Networks}
  2807. GPLv3~\S6(e) allows provision of CCS via another server when the binary or
  2808. other non-source form is distributed by peer-to-peer protocols such as
  2809. BitTorrent. Here the requirement is only that each peer be effectively
  2810. informed of the location of the source code on a server as above.
  2811. GPLv3 really did require this addition, even though it adds complexity to
  2812. a key section of GPL\@. In particular,
  2813. Decentralized peer-to-peer file sharing present a challenge
  2814. to the unidirectional view of distribution that is implicit in GPLv2 and
  2815. initial drafts of GPLv3. Identification of an upstream/downstream link in
  2816. BitTorrent distribution is neither straightforward nor reasonable; such
  2817. distribution is multidirectional, cooperative and (somewhat) anonymous. In peer-to-peer
  2818. distribution systems, participants act both as transmitters and recipients of
  2819. blocks of a particular file, but they perceive the experience merely as users
  2820. and receivers, and not as distributors in any conventional sense. At any
  2821. given moment of time, most peers will not have the complete file.
  2822. Meanwhile, GPLv3~\S6(d) permits distribution of a work in object code form
  2823. over a network, provided that the distributor offers equivalent access to
  2824. copy the Corresponding Source Code ``in the same way through the same
  2825. place''. This wording might be interpreted to permit peer-to-peer
  2826. distribution of binaries \textit{if} they are packaged together with the CCS,
  2827. but such packaging is impractical, for at least three reasons. First, even if
  2828. the CCS is packaged with the object code, it will only be available to a
  2829. non-seeding peer at the end of the distribution process, but the peer will
  2830. already have been providing parts of the binary to others in the network.
  2831. Second, in practice, peer-to-peer forms of transmission are poorly suited
  2832. means for distributing CCS. In large distributions, packaging CCS with the
  2833. object code may result in a substantial increase in file size and
  2834. transmission time. Third, in current practice, CCS packages themselves tend
  2835. \textit{not} to be transmitted through BitTorrent --- owing to reduced demand
  2836. -- thus, there generally will be too few participants downloading the same
  2837. source package at the same time to enable effective seeding and distribution.
  2838. GPLv3~\S6(e) addresses these issues. If a licensee conveys such a work of
  2839. object code using peer-to-peer transmission, that licensee is in compliance
  2840. with GPLv3~\S6 if the licensee informs other peers where the object code and
  2841. its CCS are publicly available at no charge under subsection GPLv3~\S6(d).
  2842. The CCS therefore need not be provided through the peer-to-peer system that
  2843. was used for providing the binary.
  2844. Second, GPLv3\S9 also clarifies that ancillary propagation of a covered work
  2845. that occurs as part of the process of peer-to-peer file transmission does not
  2846. require acceptance, just as mere receipt and execution of the Program does
  2847. not require acceptance. Such ancillary propagation is permitted without
  2848. limitation or further obligation.
  2849. % FIXME-LATER: Would be nice to explain much more about interactions between
  2850. % the various options of GPLv3~\S6(a-e), which might all be in play at once!
  2851. \subsection{User Products, Installation Information and Device Lock-Down}
  2852. As discussed in \S~\ref{GPLv3-drm} of this tutorial, GPLv3 seeks to thwart
  2853. technical measures such as signature checks in hardware to prevent
  2854. modification of GPL'd software on a device.
  2855. To address this issue, GPLv3~\S6 requires that parties distributing object
  2856. code provide recipients with the source code through certain means. When
  2857. those distributors pass on the CCS, they are also required to pass on any
  2858. information or data necessary to install modified software on the particular
  2859. device that included it. (This strategy is not unlike that used in LGPLv2.1
  2860. to enable users to link proprietary programs to modified libraries.)
  2861. % FIXME-LATER: LGPLv2.1 section should talk about this explicitly and this
  2862. % should be a forward reference here
  2863. \subsubsection{User Products}
  2864. \label{user-product}
  2865. The scope of these requirements is narrow. GPLv3~\S6 introduces the concept
  2866. of a ``User Product'', which includes devices that are sold for personal,
  2867. family, or household use. Distributors are only required to provide
  2868. Installation Information when they convey object code in a User Product.
  2869. In brief, the right to convey object code in a defined class of ``User
  2870. Products,'' under certain circumstances, depends on providing whatever information
  2871. is required to enable a recipient to replace the object code with a functioning
  2872. modified version.
  2873. This was a compromise that was difficult for the FSF to agree to during the
  2874. GPLv3 drafting process. However, companies and governments that use
  2875. specialized or enterprise-level computer facilities reported that they
  2876. actually \textit{want} their systems not to be under their own control.
  2877. Rather than agreeing to this as a concession, or bowing to pressure, they ask
  2878. for this as a \textit{preference}. It is not clear that the GPL should interfere
  2879. here, since the main problem lies elsewhere.
  2880. While imposing technical barriers to modification is wrong regardless of
  2881. circumstances, the areas where restricted devices are of the greatest
  2882. practical concern today fall within the User Product definition. Most, if
  2883. not all, technically-restricted devices running GPL-covered programs are
  2884. consumer electronics devices. Moreover, the disparity in clout between the
  2885. manufacturers and these users makes it difficult for the users to reject
  2886. technical restrictions through their weak and unorganized market power. Even
  2887. limited to User Products, this provision addresses the fundamental problem.
  2888. % FIXME-LATER: link \href to USC 2301
  2889. The core of the User Product definition is a subdefinition of ``consumer
  2890. product'' adapted from the Magnuson-Moss Warranty Act, a federal
  2891. consumer protection law in the USA found in 15~USC~\S2301: ``any tangible
  2892. personal property which is normally used for personal, family, or household
  2893. purposes.'' The USA has had three decades of experience of liberal
  2894. judicial and administrative interpretation of this definition in a manner
  2895. favorable to consumer rights.\footnote{The Magnuson-Moss consumer product
  2896. definition itself has been influential in the USA and Canada, having been
  2897. adopted in several state and provincial consumer protection laws.}
  2898. Ideally, this body of interpretation\footnote{The FSF, however, was very
  2899. clear that incorporation of such legal interpretation was in no way
  2900. intended to work as a general choice of USA law for GPLv3.} will guide
  2901. interpretation of the consumer product subdefinition in GPLv3~\S6, and this
  2902. will hopefully provide a degree of legal certainty advantageous to device
  2903. manufacturers and downstream licensees alike.
  2904. One well-established interpretive principle under Magnuson-Moss is that
  2905. ambiguities are resolved in favor of coverage. That is, in cases where
  2906. it is not clear whether a product falls under the definition of consumer
  2907. product, the product will be treated as a consumer product.\footnote{16
  2908. CFR~\S\ 700.1(a); \textit{McFadden v.~Dryvit Systems, Inc.}, 54
  2909. UCC~Rep.~Serv.2d 934 (D.~Ore.~2004).} Moreover, for a given product,
  2910. ``normally used'' is understood to refer to the typical use of that type
  2911. of product, rather than a particular use by a particular buyer.
  2912. Products that are commonly used for personal as well as commercial
  2913. purposes are consumer products, even if the person invoking rights is a
  2914. commercial entity intending to use the product for commercial
  2915. purposes.\footnote{16 CFR \S \ 700.1(a). Numerous court decisions
  2916. interpreting Magnuson-Moss are in accord; see, e.g., \textit{Stroebner
  2917. Motors, Inc.~v.~Automobili Lamborghini S.p.A.}, 459 F.~Supp.2d 1028,
  2918. 1033 (D.~Hawaii 2006).} Even a small amount of ``normal'' personal use
  2919. is enough to cause an entire product line to be treated as a consumer
  2920. product under Magnuson-Moss.\footnote{\textit{Tandy Corp.~v.~Marymac
  2921. Industries, Inc.}, 213 U.S.P.Q.~702 (S.D.~Tex.~1981). In this case, the
  2922. court concluded that TRS-80 microcomputers were consumer products, where
  2923. such computers were designed and advertised for a variety of users,
  2924. including small businesses and schools, and had only recently been
  2925. promoted for use in the home.}
  2926. However, Magnuson-Moss is not a perfect fit because in the area of components
  2927. of dwellings, the settled interpretation under Magnuson-Moss is under-inclusive.
  2928. Depending on how such components are manufactured or sold, they may or may
  2929. not be considered Magnuson-Moss consumer products.\footnote{Building
  2930. materials that are purchased directly by a consumer from a retailer, for
  2931. improving or modifying an existing dwelling, are consumer products under
  2932. Magnuson-Moss, but building materials that are integral component parts of
  2933. the structure of a dwelling at the time that the consumer buys the dwelling
  2934. are not consumer products. 16 C.F.R.~\S\S~700.1(c)--(f); Federal Trade
  2935. Commission, Final Action Concerning Review of Interpretations of
  2936. Magnuson-Moss Warranty Act, 64 Fed.~Reg.~19,700 (April 22, 1999); see also,
  2937. e.g., \textit{McFadden}, 54 U.C.C.~Rep.~Serv.2d at 934.} Therefore, GPLv3
  2938. defines User Products as a superset of consumer products that also includes
  2939. ``anything designed or sold for incorporation into a dwelling.''
  2940. Thus, the three sentences in the center of GPLv3's User Product definition
  2941. encapsulate the judicial and administrative principles established over the
  2942. past three decades in the USA concerning the Magnuson-Moss consumer product
  2943. definition. First, it states that doubtful cases are resolved in favor of
  2944. coverage under the definition. Second, it indicates that the words ``normally
  2945. used'' in the consumer product definition refer to a typical or common use of
  2946. a class of product, and not the status of a particular user or expected or
  2947. actual uses by a particular user. Third, it clearly states that the
  2948. existence of substantial non-consumer uses of a product does not negate a
  2949. determination that it is a consumer product, unless such non-consumer uses
  2950. represent the only significant mode of use of that product.
  2951. It should be clear from these added sentences that it is the general mode of
  2952. use of a product that determines objectively whether or not it is a consumer
  2953. product. One could not escape the effects of the User Products provisions by
  2954. labeling what is demonstrably a consumer product in ways that suggest it is
  2955. ``for professionals'', for example.
  2956. \subsubsection{Installation Information}
  2957. \label{GPLv3-installation-information}
  2958. With the User Products definition complete, the ``Installation Information''
  2959. definition uses that to define what those receiving object code inside a User
  2960. Product must receive.
  2961. Installation Information is information that is ``required to install and
  2962. execute modified versions of a covered work \dots from a modified version of
  2963. its'' CCS, in the same User Product for which the covered work is conveyed.
  2964. GPLv3 provides guidance concerning how much information must be provided: it
  2965. ``must suffice to ensure that the continued functioning of the modified
  2966. object code is in no case prevented or interfered with solely because
  2967. modification has been made.'' For example, the information provided would be
  2968. insufficient if it enabled a modified version to run only in a disabled
  2969. fashion, solely because of the fact of modification (regardless of the actual
  2970. nature of the modification). The information need not consist of
  2971. cryptographic keys; Installation Information may be ``any methods,
  2972. procedures, authorization keys, or other information''.
  2973. Note that GPLv3 does not define ``continued functioning'' further. However,
  2974. GPLv3 does provide some additional guidance concerning the scope of
  2975. GPLv3-compliant action or inaction that distributors of
  2976. technically-restricted User Products can take with respect to a downstream
  2977. recipient who replaces the conveyed object code with a modified version.
  2978. First of all, GPLv3 makes clear that GPLv3 implies no obligation ``to
  2979. continue to provide support service, warranty, or updates'' for such a work.
  2980. Second, most technically-restricted User Products are designed to communicate
  2981. across networks. It is important for both users and network providers to
  2982. know when denial of network access to devices running modified versions
  2983. becomes a GPL violation. GPLv3 permits denial of access in two cases: ``when
  2984. the modification itself materially and adversely affects the operation of the
  2985. network,'' and when the modification itself ``violates the rules and
  2986. protocols for communication across the network''. The second case is
  2987. deliberately drawn in general terms, and it serves as a foundation for
  2988. reasonable enforcement policies that respect recipients' right to modify
  2989. while recognizing the legitimate interests of network providers.
  2990. Note that GPLv3 permits the practice of conveying object code in a mode not
  2991. practically susceptible to modification by any party, such as code burned in
  2992. ROM or embedded in silicon. The goal of the Installation Information
  2993. requirement is to ensure the downstream licensee receives the real right to
  2994. modify when the device manufacturer or some other party retains that right.
  2995. Accordingly, GPLv3\S6's ante-penultimate paragraph states that the
  2996. requirement to provide Installation Information ``does not apply if neither
  2997. you nor any third party retains the ability to install modified object code
  2998. on the User Product''.
  2999. Finally, GPLv3\S6 makes it clear that there is also no requirement to
  3000. provide warranty or support for the User Product itself.
  3001. \subsection{GPLv3~\S7: Additional Permissions}
  3002. \label{GPLv3s7}
  3003. The GPL is a statement of permissions, some of which have conditions.
  3004. Additional terms --- terms that supplement those of the GPL --- may come to be
  3005. placed on, or removed from, GPL-covered code in certain common ways.
  3006. Copyleft licensing theorists have generally called
  3007. those added terms ``additional permissions'' if they grant
  3008. exceptions from the conditions of the GPL, and ``additional requirements'' if
  3009. they add conditions to the basic permissions of the GPL\@. The treatment of
  3010. additional permissions and additional requirements under GPLv3 is necessarily
  3011. asymmetrical, because they do not raise the same interpretive
  3012. issues; in particular, additional requirements, if allowed without careful
  3013. limitation, could transform a GPL'd program into a non-free one.
  3014. Due to the latter fear, historically, GPLv2 did not permit any additional
  3015. requirements. However, over time,
  3016. many copyright holders generally tolerated certain types of benign additional requirements
  3017. merely through a ``failure to enforce'' estoppel-esque scenario. Therefore, GPLv3 allows
  3018. for some specific limited requirement variations that GPLv2 technically prohibits.
  3019. With these principles in the background, GPLv3~\S7 answers the following
  3020. questions:
  3021. \begin{enumerate}
  3022. \item How does the presence of additional terms on all or part of a GPL'd program
  3023. affect users' rights?
  3024. \item When and how may a licensee add terms to code being
  3025. distributed under the GPL?
  3026. \item When may a licensee remove additional terms?
  3027. \end{enumerate}
  3028. Additional permissions present the easier case. Since the mid-1990s,
  3029. permissive exceptions often appeared alongside GPLv2 to allow combination
  3030. with certain non-free code. Typically, downstream
  3031. stream recipients could remove those exceptions and operate under pure GPLv2.
  3032. Similarly, LGPLv2.1 is in essence a permissive variant of GPLv2,
  3033. and it permits relicensing under the GPL\@.
  3034. These practices are now generalized via GPLv3~\S7.
  3035. A licensee may remove any additional permission from
  3036. a covered work, whether it was placed by the original author or by an
  3037. upstream distributor. A licensee may also add any kind of additional
  3038. permission to any part of a work for which the licensee has, or can give,
  3039. appropriate copyright permission. For example, if the licensee has written
  3040. that part, the licensee is the copyright holder for that part and can
  3041. therefore give additional permissions that are applicable to it.
  3042. Alternatively, the part may have been written by someone else and licensed,
  3043. with the additional permissions, to that licensee. Any additional
  3044. permissions on that part are, in turn, removable by downstream recipients.
  3045. As GPLv3~\S7\P1 explains, the effect of an additional permission depends on
  3046. whether the permission applies to the whole work or a part.
  3047. % FIXME-LATER: LGPLv3 will have its own section
  3048. Indeed, LGPLv3 is itself simply a list of additional permissions supplementing the
  3049. terms of GPLv3. GPLv3\S7 has thus provided the basis for recasting a
  3050. formally complex license as an elegant set of added terms, without changing
  3051. any of the fundamental features of the existing LGPL\@. LGPLv3 is thus a model for developers wishing to license their works under the
  3052. GPL with permissive exceptions. The removability of additional permissions
  3053. under GPLv3\S7 does not alter any existing behavior of the LGPL since the LGPL
  3054. has always allowed relicensing under the ordinary GPL\@.
  3055. \section{GPLv3~\S7: Understanding License Compatibility}
  3056. \label{license-compatibility}
  3057. A challenge that faced the Free Software community heavily through out the
  3058. early 2000s was the proliferation of incompatible Free Software licenses. Of
  3059. course, the GPL cannot possibly be compatible with all such licenses.
  3060. However, GPLv3
  3061. contains provisions that are designed to reduce license incompatibility by
  3062. making it easier for developers to combine code carrying non-GPL terms with
  3063. GPL'd code.
  3064. This license compatibility issue arises for
  3065. three reasons. First, the GPL is a strong copyleft license, requiring
  3066. modified versions to be distributed under the GPL\@. Second, the GPL states
  3067. that no further restrictions may be placed on the rights of recipients.
  3068. Third, all other software freedom respecting licenses in common use contain certain
  3069. requirements, many of which are not conditions made by the GPL\@. Thus, when
  3070. GPL'd code is modified by combination with code covered by another formal
  3071. license that specifies other requirements, and that modified code is then
  3072. distributed to others, the freedom of recipients may be burdened by
  3073. additional requirements in violation of the GPL. It can be seen that
  3074. additional permissions in other licenses do not raise any problems of license
  3075. compatibility.
  3076. GPLv3 took a new approach to the issue of combining GPL'd code with
  3077. code governed by the terms of other software freedom licenses. Traditional
  3078. GPLv2 license compatibility theory (which was not explicitly stated in GPLv2
  3079. itself, but treated as a license interpretation matter by the FSF) held that GPLv2 allowed such
  3080. combinations only if the non-GPL licensing terms permitted distribution under
  3081. the GPL and imposed no restrictions on the code that were not also imposed by
  3082. the GPL\@. In practice, the FSF historically supplemented that policy with a structure of
  3083. exceptions for certain kinds of combinations.
  3084. GPLv3~\S7 implements a more explicit policy on license
  3085. compatibility. It formalizes the circumstances under which a licensee may
  3086. release a covered work that includes an added part carrying non-GPL terms.
  3087. GPLv3~\S7 distinguish between terms that provide additional permissions, and terms that
  3088. place additional requirements on the code, relative to the permissions and
  3089. requirements established by applying the GPL to the code.
  3090. As discussed in the previous section of this tutorial, GPLv3~\S7 first and foremost explicitly allows added parts covered by terms with
  3091. additional permissions to be combined with GPL'd code. This codifies the
  3092. existing practice of regarding such licensing terms as compatible with the
  3093. GPL\@. A downstream user of a combined GPL'd work who modifies such an added
  3094. part may remove the additional permissions, in which case the broader
  3095. permissions no longer apply to the modified version, and only the terms of
  3096. the GPL apply to it.
  3097. In its treatment of terms that impose additional requirements, GPLv3\S7
  3098. extends the range of licensing terms with which the GPL is compatible. An
  3099. added part carrying additional requirements may be combined with GPL'd code,
  3100. but only if those requirements belong to a set enumerated in GPLv3\S7. There
  3101. are, of course, limits on the acceptable additional requirements, which
  3102. ensures that enhanced license compatibility does not
  3103. defeat the broader software-freedom-defending terms of the GPL\@. Unlike terms that grant
  3104. additional permissions, terms that impose additional requirements cannot be
  3105. removed by a downstream user of the combined GPL'd work, because only in the
  3106. pathological case\footnote{Theoretically, a user could collect copyright
  3107. assignment from all known contributors and then do this, but this would
  3108. indeed be the pathological case.} would a user have the right to do so.
  3109. In general, the types of additional requirements were those terms in regular
  3110. use by other non-copyleft Free Software licenses that the FSF found
  3111. unobjectionable. The specific details GPLv3's permitted additional
  3112. requirements hat GPLv3 are as follows:
  3113. \begin{enumerate}[label=7(\alph*):,ref=GPLv3s7\alph*]
  3114. \item This provision allows alternative ``disclaimer of warranty''
  3115. forms. Copyright holders can disclaim warranty or limit liability
  3116. differently from the terms as provided under GPLv3\S~\S15--16. Drafters
  3117. included this permission to advance the internationalization goals of
  3118. GPLv3; international treaties lack adequate harmonization for laws
  3119. regarding warranty and disclaimer.
  3120. \item This provision allows alternative requirements for preservation of
  3121. appropriate legal notices. GPLv3 permits additional requirements regarding
  3122. preservation of legal notices, including on output from execution of
  3123. covered works. Preserved information can include information about the
  3124. origins of the code or alterations of the code.
  3125. \item This provision allows prohibition of misrepresentation of original
  3126. material. The provision yields compatibility with non-copyleft Free
  3127. Software licenses that require marking of modified versions in
  3128. ``reasonable''ways which differ from GPL's own precise marking
  3129. requirements.
  3130. \item This provision allows limitations on the use of names of licensor for
  3131. publicity purposes. This provision also yields additional compatibility
  3132. with non-copyleft Free Software licenses that prohibit the use of the
  3133. licensor's name on unmodified versions (or other prohibitions on
  3134. advertising rights). The third clause of the
  3135. \href{http://opensource.org/licenses/BSD-3-Clause}{3-Clause BSD
  3136. License}, for example, long considered de-facto compatible with GPLv2
  3137. anyway, is via this clause unequivocally compatible with GPLv3. However,
  3138. \href{https://www.gnu.org/licenses/license-list.html#OriginalBSD}{this
  3139. clause \textit{does not} make GPL compatible with the old BSD
  3140. advertising clause} that the FSF
  3141. \href{https://www.gnu.org/philosophy/bsd.html}{long ago identified as
  3142. problematic}.
  3143. \item This provision clarifies that refusal to grant trademark rights for a
  3144. GPLv3'd covered work remains compatible with GPLv3. Again, some
  3145. non-copyleft permissive licenses include such clauses.
  3146. \item This provision allows indemnification requirements of authors and
  3147. licensors. The FSF specifically designed this clause to achieve GPLv3
  3148. compatibility for the
  3149. \href{http://www.apache.org/licenses/LICENSE-2.0.html}{Apache Software
  3150. License, Version 2.0}.
  3151. \end{enumerate}
  3152. During the GPLv3 drafting process, some questioned the necessity of GPLv3~\S7;
  3153. those critics suggested that it creates complexity that did not previously
  3154. exist. However, by the time of GPLv3's drafting, many existing GPLv2'd
  3155. software packages already combined with various non-copylefted Free Software
  3156. licensed code that carried such additional terms. Therefore, GPLv3~\S7 is
  3157. rationalized existing practices of those package authors and modifiers, since
  3158. it sets clear guidelines regarding the removal and addition of these
  3159. additional terms. With its carefully limited list of allowed additional
  3160. requirements, GPLv3\S7 accomplishes additional objectives as well, since it
  3161. permits the expansion of the base of code available for GPL developers, while
  3162. also encouraging useful experimentation with requirements the GPLv3 does not
  3163. include by default.
  3164. However, any other non-permissive additional terms apart from those stated
  3165. above are considered ``further'' restrictions which
  3166. \hyperref[GPLv3s10]{GPLv3~\S10} prohibits. Furthermore, as a compliance
  3167. matter, if you add additional terms in accordance with GPLv3~\S7, you must
  3168. ensure that the terms are placed in the relevant source files or provide a
  3169. conspicuous notice about where to find the additional terms.
  3170. \section{GPLv3~\S8: A Lighter Termination}
  3171. GPLv2 provided for automatic termination of the rights of a person who
  3172. copied, modified, sublicensed, or distributed a work in violation of the
  3173. license. Automatic termination can be too harsh for those who have committed
  3174. an inadvertent violation, particularly in cases involving distribution of
  3175. large collections of software having numerous copyright holders. A violator
  3176. who resumes compliance with GPLv2 technically needs to obtain forgiveness
  3177. from all copyright holders, and even contacting them all might be impossible.
  3178. GPLv3~\S8 now grants opportunities for provisional and permanent
  3179. reinstatement of rights. The termination procedure provides a limited
  3180. opportunity to cure license violations. If a licensee has committed a
  3181. first-time violation of the GPL with respect to a given copyright holder, but
  3182. the licensee cures the violation within 30 days following receipt of notice
  3183. of the violation, then any of the licensee's GPL rights that have been
  3184. terminated by the copyright holder are ``automatically reinstated''.
  3185. Finally, if a licensee violates the GPL, a contributor may terminate any
  3186. patent licenses that it granted under GPLv3~\S11, in addition to any
  3187. copyright permissions the contributor granted to the licensee.
  3188. % FIXME-LATER: write more here, perhaps linking up to enforcement
  3189. \section{GPLv3~\S9: Acceptance}
  3190. GPLv3~\S9 means what it says: mere receipt or execution of code neither
  3191. requires nor signifies contractual acceptance under the GPL. Speaking more
  3192. broadly, GPLv3 is intentionally structured as a unilateral grant
  3193. of copyright permissions, the basic operation of which exists outside of any
  3194. law of contract. Whether and when a contractual relationship is formed
  3195. between licensor and licensee under local law do not necessarily matter to
  3196. the working of the license.
  3197. \section{GPLv3~\S10: Explicit Downstream License}
  3198. \label{GPLv3s10}
  3199. GPLv3~\S10 is a generally straightforward section that ensures that everyone
  3200. downstream receives licenses from all copyright holders. Each time you
  3201. redistribute a GPL'd program, the recipient automatically receives a license,
  3202. under the terms of GPL, from every upstream licensor whose copyrighted
  3203. material is present in the work you redistribute. You could think of this as
  3204. creating a three-dimensional rather than linear flow of license rights.
  3205. Every recipient of the work is ``in privity,'' or is directly receiving a
  3206. license from every licensor.
  3207. This mechanism of automatic downstream licensing is central to copyleft's
  3208. function. Every licensor independently grants licenses, and every licensor
  3209. independently terminates the license on violation. Parties further
  3210. downstream from the infringing party remain licensed, so long as they don't
  3211. themselves commit infringing actions. Their licenses come directly from all
  3212. the upstream copyright holders, and are not dependent on the license of the breaching
  3213. party who distributed to them. For the same reason, an infringer who acquires
  3214. another copy of the program has not thereby acquired any new license rights:
  3215. once any upstream licensor of that program has terminated the license for
  3216. breach of its terms, no new automatic license will issue to the recipient
  3217. just by acquiring another
  3218. copy\footnote{Footnote~\ref{German-reinstatement-footnote} also applies here
  3219. in discussion of GPLv3 just as it did in discussion of GPLv2.}
  3220. Meanwhile, one specific addition in GPLv3 here in GPLv3~\S10 deserves special
  3221. mention. Specifically, GPLv3 removed the words ``at no charge'' from
  3222. GPLv2~\S2(b) (which, BTW, became GPLv3~\S5(b)) because it contributed to a misconception that the GPL did not
  3223. permit charging for distribution of copies. The purpose of the ``at no
  3224. charge'' wording was to prevent attempts to collect royalties from third
  3225. parties. The removal of these words created the danger that the imposition
  3226. of licensing fees would no longer be seen as a license violation. Therefore,
  3227. GPLv3~\S10 adds a new explicit prohibition on imposition of licensing fees or
  3228. royalties. This section is an appropriate place for such a clause, since it
  3229. is a specific consequence of the general requirement that no further
  3230. restrictions be imposed on downstream recipients of GPL-covered code.
  3231. % FIXME-LATER: This text needs further study before I can conclude it belongs
  3232. % in this tutorial:
  3233. %% Careful readers of the GPL have suggested that its explicit prohibition
  3234. %% against imposition of further restrictions\footnote{GPLv2, section 6; Draft
  3235. %% 3, section 10, third paragraph.} has, or ought to have, implications for
  3236. %% those who assert patents against other licensees. Draft 2 took some steps to
  3237. %% clarify this point in a manner not specific to patents, by describing the
  3238. %% imposition of ``a license fee, royalty, or other charge'' for exercising GPL
  3239. %% rights as one example of an impermissible further restriction. In Draft 3 we
  3240. %% have clarified further that the requirement of non-imposition of further
  3241. %% restrictions has specific consequences for litigation accusing GPL-covered
  3242. %% programs of infringement. Section 10 now states that ``you may not initiate
  3243. %% litigation (including a cross-claim or counterclaim in a lawsuit) alleging
  3244. %% that any patent claim is infringed by making, using, selling, offering for
  3245. %% sale, or importing the Program (or the contribution of any contributor).''
  3246. %% That is to say, a patent holder's licensed permissions to use a work under
  3247. %% GPLv3 may be terminated under section 8 if the patent holder files a lawsuit
  3248. %% alleging that use of the work, or of any upstream GPLv3-licensed work on
  3249. %% which the work is based, infringes a patent.
  3250. \section{GPLv3~\S11: Explicit Patent Licensing}
  3251. \label{GPLv3s11}
  3252. Software patenting is a harmful and unjust policy, and should be abolished;
  3253. recent experience makes this all the more evident. Since many countries grant
  3254. patents that can apply to and prohibit software packages, in various guises
  3255. and to varying degrees, GPLv3 seeks to protect the users of GPL-covered programs
  3256. from those patents, while at the same time making it feasible for patent
  3257. holders to contribute to and distribute GPL-covered programs as long as they
  3258. do not attack the users of those programs.
  3259. It is generally understood that GPLv2 implies some limits on a licensee's
  3260. power to assert patent claims against the use of GPL-covered works.
  3261. However, the patent licensing practice that GPLv2~\S7 (corresponding to
  3262. GPLv3~\S12) is designed to prevent is only one of several ways in which
  3263. software patents threaten to make free programs non-free and to prevent users
  3264. from exercising their rights under the GPL. GPLv3 takes a more comprehensive
  3265. approach to combating the danger of patents.
  3266. GPLv2~\S7 has seen some success in deterring conduct that would otherwise
  3267. result in denial of full downstream enjoyment of GPL rights, and thus it is
  3268. preserved in GPLv3~\S12. Experience has shown that more is necessary,
  3269. however, to ensure adequate community safety where companies act in concert
  3270. to heighten the anticompetitive use of patents that they hold or license.
  3271. Therefore, GPLv3 is designed to reduce the patent risks that distort and
  3272. threaten the activities of users who make, run, modify and share Free
  3273. Software. At the same time, GPLv3 gives favorable consideration to practical
  3274. goals such as certainty and administrability for patent holders that
  3275. participate in distribution and development of GPL-covered software. GPLv3's
  3276. policy requires each such patent holder to provide appropriate levels of
  3277. patent assurance to users, according to the nature of the patent holder's
  3278. relationship to the program.
  3279. In general, GPLv3 provides for two classes of patent commitments:
  3280. \begin{itemize}
  3281. \item Grant of license to claims in contributor versions: GPLv3~\S11
  3282. introduces an affirmative grant of rights to patent claims by those who
  3283. contribute code to GPL'd programs. The intent is to prevent parties from
  3284. aggressively asserting patents against users of code those parties have
  3285. themselves modified --- in theory preventing betrayal by ``insiders'' of
  3286. the copyleft community. A contributor's patent claims necessarily
  3287. infringed by the version of the program created by the incorporation of its
  3288. modifications are licensed to all subsequent users and modifiers of the
  3289. program, or programs based on the program. No patent claims only infringed
  3290. by subsequent modifications by other parties are thus licensed. Patent
  3291. claims acquired after the making of the ``contributor version'' necessarily
  3292. infringed by that version are also licensed by this provision at the time
  3293. of their acquisition or perfection.
  3294. \item Prohibition of enforcement of patent claims against those to whom you
  3295. distribute: GPLv3~\S10 makes explicit that licensees who directly
  3296. distribute may not make demands for acceptance of patent licenses or
  3297. payment of patent royalties from distribution recipients. This provision
  3298. establishes a uniform rule of patent exhaustion with respect to GPL'd
  3299. programs regardless of the domestic patent law in any particular system or
  3300. locale.
  3301. \end{itemize}
  3302. The following two subsections discuss in order each of the above mentioned
  3303. classes of patent commitments.
  3304. \subsection{The Contributor's Explicit Patent License}
  3305. Specifically, the ideal might have been for GPLv3 to feature a patent license
  3306. grant triggered by all acts of distribution of GPLv3-covered works. The FSF
  3307. considered it during the GPLv3 drafting process, but many patent-holding
  3308. companies objected to this policy. They have made two objections: (1) the
  3309. far-reaching impact of the patent license grant on the patent holder is
  3310. disproportionate to the act of merely distributing code without modification
  3311. or transformation, and (2) it is unreasonable to expect an owner of vast
  3312. patent assets to exercise requisite diligence in reviewing all the
  3313. GPL-covered software that it provides to others. Some expressed particular
  3314. concern about the consequences of ``inadvertent'' distribution.
  3315. The argument that the impact of the patent license grant would be
  3316. ``disproportionate'', that is to say unfair, is not valid. Since
  3317. software patents are weapons that no one should have, and using them for
  3318. aggression against free software developers is an egregious act (thus
  3319. preventing that act cannot be unfair).
  3320. However, the second argument seems valid in a practical sense. A
  3321. typical GNU/Linux distribution includes thousands of programs. It would
  3322. be quite difficult for a re-distributor with a large patent portfolio to
  3323. review all those programs against that portfolio every time it receives
  3324. and passes on a new version of the distribution. Moreover, this question
  3325. raises a strategic issue. If the GPLv3 patent license requirements
  3326. convince patent-holding companies to remain outside the distribution
  3327. path of all GPL-covered software, then these requirements, no matter how
  3328. strong, will cover few patents.
  3329. GPLv3 therefore makes a partial concession
  3330. which would lead these companies to feel secure in doing the
  3331. distribution themselves. GPLv3~\S11
  3332. applies only to those distributors that have
  3333. modified the program. The other changes we have made in sections 10 and
  3334. 11 provide strengthened defenses against patent assertion and compensate
  3335. partly for this concession.
  3336. Therefore, GPLv3~\S11 introduces the terms ``contributor'', ``contributor version'', and
  3337. ``essential patent claims'', which are
  3338. used in the GPLv3~\S11\P3. Viewed from the perspective of a recipient of the
  3339. Program, contributors include all the copyright holders for the Program,
  3340. other than copyright holders of material originally licensed under non-GPL
  3341. terms and later incorporated into a GPL-covered work. The contributors are
  3342. therefore the initial GPLv3 licensors of the Program and all subsequent
  3343. upstream licensors who convey, under the terms of GPLv3~\S5, modified covered
  3344. works.
  3345. Thus, the ``contributor version'' includes the material the contributor has copied from the
  3346. upstream version that the contributor has modified. GPLv3~\S11\P3
  3347. does not apply to those that redistribute the program
  3348. without change.\footnote{An implied patent license from the distributor,
  3349. however, often arises. See \S~\ref{gpl-implied-patent-grant} in this tutorial}
  3350. In other words, the ``contributor version'' includes not just
  3351. the material added or altered by the contributor, but also the pre-existing
  3352. material the contributor copied from the upstream version and retained in the
  3353. modified version. (GPLv3's usage of ``contributor'' and ``contribution'' should
  3354. not be confused with the various other ways in which those terms are used in
  3355. certain other free software licenses.\footnote{Cf., e.g., Apache License,
  3356. version 2.0, section 1; Eclipse Public License, version 1.0, section 1;
  3357. Mozilla Public License, version 1.1, section 1.1.})
  3358. Some details of the ``essential patent claims'' definition deserve special
  3359. mention. ``Essential patent claims'', for a given party, are a subset of the
  3360. claims ``owned or controlled'' by the party. They do include sublicensable
  3361. claims that have been licensed to the contributor by a third
  3362. party.\footnote{This issue is typically handled in other software freedom
  3363. licenses having patent licensing provisions by use of the unhelpful term
  3364. ``licensable,'' which is either left undefined or is given an ambiguous
  3365. definition.} Most commercial patent license agreements that permit
  3366. sublicensing do so under restrictive terms that are inconsistent with the
  3367. requirements of the GPL\@. For example, some patent licenses allow the
  3368. patent licensee to sublicense but require collection of royalties from any
  3369. sublicensees. The patent licensee could not distribute a GPL-covered program
  3370. and grant the recipient a patent sublicense for the program without violating
  3371. section 12 of GPLv3.\footnote{GPLv3 also provides an example in section 12
  3372. that makes this point clear.} In rare cases, however, a conveying party
  3373. can freely grant patent sublicenses to downstream recipients without
  3374. violating the GPL\@.
  3375. Additionally, ``essential patent claims'' are those patents ``that would be
  3376. infringed by some manner, permitted by this License, of making, using, or
  3377. selling the work''. This intends to make clear that a patent claim is
  3378. ``essential'' if some mode of usage would infringe that claim, even if there
  3379. are other modes of usage that would not infringe.
  3380. Finally, ``essential patent claims \ldots do not include
  3381. claims that would be infringed only as a consequence of further
  3382. modification of the work.'' The set of essential patent
  3383. claims licensed is fixed by the
  3384. particular version of the work that was contributed. The claim set
  3385. cannot expand as a work is further modified downstream. (If it could,
  3386. then any software patent claim would be included, since any software
  3387. patent claim can be infringed by some further modification of the
  3388. work.)\footnote{However, ``the work'' should not be understood to be
  3389. restricted to a particular mechanical affixation of, or medium for
  3390. distributing, a program, where the same program might be provided in
  3391. other forms or in other ways that may be captured by other patent claims
  3392. held by the contributor.}
  3393. \medskip
  3394. Ideally, this contributor patent policy will result in fairly frequent licensing of patent
  3395. claims by contributors. A contributor is charged with awareness of the fact
  3396. that it has modified a work and provided it to others; no act of contribution
  3397. should be treated as inadvertent. GPLv3's rule also requires no more work, for a
  3398. contributor, than the weaker rule proposed by the patent holders. Under
  3399. their rule, the contributor must always compare the entire work against its
  3400. patent portfolio to determine whether the combination of the modifications
  3401. with the remainder of the work cause it to read on any of the contributor's
  3402. patent claims.
  3403. Finally, GPLv3's explicit patent license for contributors has an interesting
  3404. and useful side effect. When a company with a large number of such claims
  3405. acquires the program's modifier, all claims held or thereafter acquired by
  3406. the purchaser are automatically licensed under this provision. For example,
  3407. Microsoft's acquisition of Nokia resulted in the automatic licensing of all
  3408. Microsoft patent claims now or hereafter acquired which read on any
  3409. contributor version of any GPLv3 program ever modified by Nokia.
  3410. \subsection{Conveyors' Patent Licensing}
  3411. The remaining patent licensing in GPLv3 deals with patent licenses that are
  3412. granted by conveyance. The licensing is not as complete or far reaching as
  3413. the contributor patent licenses discussed in the preceding section.
  3414. The term ``patent license,'' as used in GPLv3~\S11\P4--6, is not meant to be
  3415. confined to agreements formally identified or classified as patent licenses.
  3416. GPLv3~\S11\P3 makes this clear by defining ``patent
  3417. license,'' for purposes of the subsequent three paragraphs, as ``any express
  3418. agreement or commitment, however denominated, not to enforce a patent
  3419. (such as an express permission to practice a patent or covenant not to
  3420. sue for patent infringement)''
  3421. % FIXME-LATER: I want to ask Fontana about this before adding it.
  3422. % The definition does not include patent licenses that arise by
  3423. % implication or operation of law, because the third through fifth paragraphs
  3424. % of section 11 are specifically concerned with explicit promises that purport
  3425. % to be legally enforceable.
  3426. GPLv3~\S11\P5 is commonly called GPLv3's downstream shielding provision. It
  3427. responds particularly to the problem of exclusive deals between patent
  3428. holders and distributors, which threaten to distort the free software
  3429. distribution system in a manner adverse to developers and users. The
  3430. fundamental idea is to make a trade-off between assuring a patent license for
  3431. downstream and making (possibly patent-encumbered) CCS publicly available.
  3432. Simply put, in nearly all cases in which the ``knowingly relying'' test is
  3433. met, the patent license will indeed not be sublicensable or generally
  3434. available to all on free terms. If, on the other hand, the patent license is
  3435. generally available under terms consistent with the requirements of the GPL,
  3436. the distributor is automatically in compliance, because the patent license
  3437. has already been extended to all downstream recipients. Finally, if the
  3438. patent license is sublicensable on GPL-consistent terms, the distributor may
  3439. choose to grant sublicenses to downstream recipients instead of causing the
  3440. CCS to be publicly available. (In such a case, if the distributor is also a
  3441. contributor, it will already have granted a patent sublicense anyway, and so
  3442. it need not do anything further to comply with the third paragraph.)
  3443. Admittedly, public disclosure of CCS is not necessarily required by other
  3444. sections of the GPL, and the FSF in drafting GPLv3 did not necessarily wish
  3445. to impose a general requirement to make source code available to all, which
  3446. has never been a GPL condition. However, many vendors who produce products
  3447. that include copylefted software, and who are most likely to be affected by the
  3448. downstream shielding provision, lobbied for the addition of the source code
  3449. availability option, so it remains.
  3450. % FIXME-LATER: This text is likely redundant and a bit confusing. Needs work
  3451. % to use.
  3452. %% If A takes a patent license from B that benefits A only, rather than A's
  3453. %% customers or their distributees, A imposes risk from B's patents on others
  3454. %% that it does not suffer itself. Under many circumstances, this is an
  3455. %% acceptable outcome. If, however, A is the only possible source of the
  3456. %% program, by taking such a license and distributing in reliance on it, A is in
  3457. %% effect helping B to ``take the program private.''
  3458. % FIXME-LATER: end
  3459. Meanwhile, two specific alternatives to the source code availability option
  3460. are also available. The distributor may comply by disclaiming the patent
  3461. license it has been granted for the conveyed work, or by arranging to extend
  3462. the patent license to downstream recipients.\footnote{The latter option, if
  3463. chosen, must be done ``in a manner consistent with the requirements of this
  3464. License''; for example, it is unavailable if extension of the patent
  3465. license would result in a violation of GPLv3~\S 12.} The GPL is intended
  3466. to permit private distribution as well as public distribution, and the
  3467. addition of these options ensures that this remains the case, even though it
  3468. remains likely that distributors in this situation will usually choose the
  3469. source code availability option.
  3470. Note that GPLv3~\S11\P5 is activated only if the CCS is not already otherwise
  3471. publicly available. (Most often it will, in fact, already be available on
  3472. some network server operated by a third party.) Even if it is not already
  3473. available, the option to ``cause the Corresponding Source to be so
  3474. available'' can then be satisfied by verifying that a third party has acted
  3475. to make it available. That is to say, the affected distributor need not
  3476. itself host the CCS to take advantage of the source code availability option.
  3477. This subtlety may help the distributor avoid certain peculiar assumptions of
  3478. liability.
  3479. Note that GPLv3~\S11\P6--7 are designed to stop distributors from colluding with
  3480. third parties to offer selective patent protection. GPLv3 is designed to
  3481. ensure that all users receive the same rights; arrangements that circumvent
  3482. this make a mockery of free software, and we must do everything in our power
  3483. to stop them.
  3484. First, GPLv3~\S11\P6 states that any license that protects some recipients of
  3485. GPL'd software must be extended to all recipients of the software.
  3486. If conveyors arrange to provide patent
  3487. protection to some of the people who get the software from you, that
  3488. protection is automatically extended to everyone who receives the software,
  3489. no matter how they get it.
  3490. Second, GPLv3~\S11\P7
  3491. prohibits anyone who made such an agreement from distributing software
  3492. released under GPLv3. Conveyors are prohibited from
  3493. distributing software under GPLv3 if the conveyor makes an agreement of that
  3494. nature in the future.
  3495. The date in GPLv3~\S11\P7 likely seems arbitrary to those who did not follow
  3496. the GPLv3 drafting process. This issue was hotly debated during the drafting of
  3497. GPLv3, but ultimately one specific deal of this type --- a deal between Microsoft
  3498. and Novell for Microsoft to provide so-called ``coupons'' to Microsoft customers to redeem
  3499. for copies of Novell's GNU/Linux distribution with a Microsoft patent license -- was
  3500. designed to be excluded.
  3501. The main reason for this was a tactical decision by the FSF. FSF believed they can do more to
  3502. protect the community by allowing Novell to use software under GPLv3
  3503. than by forbidding it to do so. This is because of
  3504. paragraph 6 of section 11 (corresponding to paragraph 4 in Draft 3).
  3505. It will apply, under the Microsoft/Novell deal, because of the coupons
  3506. that Microsoft has acquired that essentially commit it to participate
  3507. in the distribution of the Novell SLES GNU/Linux system.
  3508. The FSF also gave a secondary reason: to avoid affecting other kinds of agreements for
  3509. other kinds of activities. While GPLv3 sought to
  3510. distinguish pernicious deals of the Microsoft/Novell type from
  3511. business conduct that is not particularly harmful, the FSF also did not
  3512. assume success in that drafting, and thus there remained some risk that other
  3513. unchangeable past agreements could fall within the scope of GPLv3~\S11\P7.
  3514. In future deals, distributors engaging in ordinary business practices
  3515. can structure the agreements so that they do not fall under GPLv3~\S11\P7.
  3516. \section{GPLv3~\S12: Familiar as GPLv2~\S7}
  3517. \label{GPLv3s12}
  3518. GPLv2~\S12 remains almost completely unchanged from the text that appears in
  3519. GPLv2~\S7. This is an important provision that ensures a catch-all to ensure
  3520. that nothing ``surprising'' interferes with the continued conveyance safely
  3521. under copyleft.
  3522. The wording in the first sentence of GPLv3~\S12 has been revised slightly to
  3523. clarify that an agreement -- such as a litigation settlement agreement or a
  3524. patent license agreement -- is one of the ways in which conditions may be
  3525. ``imposed'' on a GPL licensee that may contradict the conditions of the GPL,
  3526. but which do not excuse the licensee from compliance with those conditions.
  3527. This change codifies the historical interpretation of GPLv2.
  3528. GPLv3 removed the limited severability clause of GPLv2~\S7 as a
  3529. matter of tactical judgment, believing that this is the best way to ensure
  3530. that all provisions of the GPL will be upheld in court. GPLv3 also removed
  3531. the final sentence of GPLv2 section 7, which the FSF consider to be unnecessary.
  3532. \section{GPLv3~\S13: The Great Affero Compromise}
  3533. The Affero GPL was written with the expectation that its
  3534. additional requirement would be incorporated into the terms of GPLv3
  3535. itself. Many software freedom advocates, including some authors of this
  3536. tutorial, advocated heavily for that, and fully expected it to happen.
  3537. The FSF, however, chose not to include the Affero clause in GPLv3, due to
  3538. what it called ``irreconcilable views from
  3539. different parts of the community''. Many
  3540. commercial users of Free Software were opposed to the inclusion of a
  3541. mandatory Affero-like requirement in the body of GPLv3 itself. In fact, some
  3542. wealthier companies even threatened to permanently fund forks of many FSF
  3543. copyrighted-programs under GPLv2 if the Affero clause appeared in GPLv3.
  3544. Meanwhile, there was disagreement even among copyleft enthusiasts about the
  3545. importance of the provision. A coalition never formed, and ultimately the
  3546. more powerful interests implicitly allied with the companies who deeply opposed
  3547. the Affero clause such that the FSF felt the Affero clause would need its own
  3548. license, but one compatible with GPLv3.
  3549. GPLv3~\S13 makes GPLv3 compatible with the AGPLv3, so that at least code can
  3550. be shared between AGPLv3'd and GPLv3'd projects, even if the Affero clause
  3551. does not automatically apply to all GPLv3'd works.
  3552. %FIXME-LATER: no time to do this justice, will come back later, instead the
  3553. %above.
  3554. %% Some of this hostility seemed to be based on a misapprehension that
  3555. %% Affero-like terms placed on part of a covered work would somehow extend
  3556. %% to the whole of the work.\footnote{It is possible that the presence of
  3557. %% the GPLv2-derived copyleft clause in the existing Affero GPL contributed
  3558. %% to this misunderstanding.} Our explanations to the contrary did little
  3559. %% to satisfy these critics; their objections to 7b4 instead evolved into a
  3560. %% broader indictment of the additional requirements scheme of section 7.
  3561. %% It was clear, however, that much of the concern about 7b4 stemmed from
  3562. %% its general formulation. Many were alarmed at the prospect of GPLv3
  3563. %% compatibility for numerous Affero-like licensing conditions,
  3564. %% unpredictable in their details but potentially having significant
  3565. %% commercial consequences.
  3566. %% On the other hand, many developers, otherwise sympathetic to the policy
  3567. %% goals of the Affero GPL, have objected to the form of the additional
  3568. %% requirement in that license. These developers were generally
  3569. %% disappointed with our decision to allow Affero-like terms through
  3570. %% section 7, rather than adopt a condition for GPLv3. Echoing their
  3571. %% concerns about the Affero GPL itself, they found fault with the wording
  3572. %% of the section 7 clause in both of the earlier drafts. We drafted 7b4
  3573. %% at a higher level than its Draft 1 counterpart based in part on comments
  3574. %% from these developers. They considered the Draft 1 clause too closely
  3575. %% tied to the Affero mechanism of preserving functioning facilities for
  3576. %% downloading source, which they found too restrictive of the right of
  3577. %% modification. The 7b4 rewording did not satisfy them, however. They
  3578. %% objected to its limitation to terms requiring compliance by network
  3579. %% transmission of source, and to the technically imprecise or inaccurate
  3580. %% use of the phrase ``same network session.''
  3581. %% We have concluded that any redrafting of the 7b4 clause would fail to
  3582. %% satisfy the concerns of both sets of its critics. The first group
  3583. %% maintains that GPLv3 should do nothing about the problem of public
  3584. %% use. The second group would prefer for GPLv3 itself to have an
  3585. %% Affero-like condition, but that seems to us too drastic. By permitting
  3586. %% GPLv3-covered code to be linked with code covered by version 2 of the
  3587. %% Affero GPL, the new section 13 honors our original commitment to
  3588. %% achieving GPL compatibility for the Affero license.
  3589. %% Version 2 of the Affero GPL is not yet published. We will work with
  3590. %% Affero, Inc., and with all other interested members of our community, to
  3591. %% complete the drafting of this license following the release of Draft 3,
  3592. %% with a goal of having a final version available by the time of our
  3593. %% adoption of the final version of GPLv3. We hope the new Affero license
  3594. %% will satisfy those developers who are concerned about the issue of
  3595. %% public use of unconveyed versions but who have concerns about the
  3596. %% narrowness of the condition in the existing Affero license.
  3597. %% As the second sentence in section 13 indicates, when a combined work is
  3598. %% made by linking GPLv3-covered code with Affero-covered code, the
  3599. %% copyleft on one part will not extend to the other part.\footnote{The
  3600. %% plan is that the additional requirement of the new Affero license will
  3601. %% state a reciprocal limitation.} That is to say, in such combinations,
  3602. %% the Affero requirement will apply only to the part that was brought into
  3603. %% the combination under the Affero license. Those who receive such a
  3604. %% combination and do not wish to use code under the Affero requirement may
  3605. %% remove the Affero-covered portion of the combination.
  3606. Meanwhile, those who criticize the permission to link with code under the Affero
  3607. GPL should recognize that most other free software licenses also permit
  3608. such linking. In particular, when a combined work is made by linking GPLv3-covered code
  3609. with AGPLv3-covered code, the copyleft on one part will not extend to the
  3610. other part. In such combinations, the Affero requirement will apply only to
  3611. the part originally brought into the combination under the Affero license.
  3612. In theory, those who receive such a combination and do not wish to use code
  3613. under the Affero requirement may remove the Affero-covered portion of the
  3614. combination. (Admittedly, in practice, de-mingling of combined code can be
  3615. technically difficult.)
  3616. \section{GPLv3~\S14: So, When's GPLv4?}
  3617. \label{GPLv3s14}
  3618. No substantive change has been made in section 14. The wording of the section
  3619. has been revised slightly to make it clearer.
  3620. It's unclear when the FSF might consider publishing GPLv4. However, this
  3621. section makes it clear that the FSF is the sole authority who can decide
  3622. such.
  3623. The main addition to this section allows a third-party proxy to be appointed
  3624. by contributors who wish someone else to make relicensing to new versions of
  3625. GPL when they are released. This is a ``halfway'' point between using ``-only''
  3626. or ``-or-later'' by consolidating the decision-making on that issue to a
  3627. single authority.
  3628. % FIXME-LATER: better proxy description
  3629. \section{GPLv3~\S15--17: Warranty Disclaimers and Liability Limitation}
  3630. No substantive changes have been made in sections 15 and 16.
  3631. % FIXME-LATER: more, plus 17
  3632. % FIXME-LATER: Section header needed here about choice of law.
  3633. % FIXME-LATER: reword into tutorial
  3634. %% Some have asked us to address the difficulties of internationalization
  3635. %% by including, or permitting the inclusion of, a choice of law
  3636. %% provision. We maintain that this is the wrong approach. Free
  3637. %% software licenses should not contain choice of law clauses, for both
  3638. %% legal and pragmatic reasons. Choice of law clauses are creatures of
  3639. %% contract, but the substantive rights granted by the GPL are defined
  3640. %% under applicable local copyright law. Contractual free software
  3641. %% licenses can operate only to diminish these rights. Choice of law
  3642. %% clauses also raise complex questions of interpretation when works of
  3643. %% software are created by combination and extension. There is also the
  3644. %% real danger that a choice of law clause will specify a jurisdiction
  3645. %% that is hostile to free software principles.
  3646. %% % FIXME-LATER: reword into tutorial, \ref to section 7.
  3647. %% Our revised version of section 7 makes explicit our view that the
  3648. %% inclusion of a choice of law clause by a licensee is the imposition of
  3649. %% an additional requirement in violation of the GPL. Moreover, if a
  3650. %% program author or copyright holder purports to supplement the GPL with
  3651. %% a choice of law clause, section 7 now permits any licensee to remove
  3652. %% that clause.
  3653. % FIXME-LATER: does this need to be a section, describing how it was out then in
  3654. % then out then in? :)
  3655. Finally, the FSF shortened the section on ``How to Apply These
  3656. Terms to Your New Programs'' to just the bare essentials.
  3657. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  3658. \chapter{The Lesser GPL}
  3659. \label{LGPLv2}
  3660. As we have seen in our consideration of the GPL, its text is specifically
  3661. designed to cover all possible derivative, modified and/or combined works under copyright law. Our
  3662. goal in designing the GPL was to maximize its use of the controls of
  3663. copyright law to maximize the number of works that were covered by GPL.
  3664. However, while the strategic goal of software freedom is to bring as much Free Software
  3665. into the world as possible, particular tactical considerations
  3666. regarding software freedom dictate different means. Extending the
  3667. copyleft effect as far as copyright law allows is not always the most
  3668. prudent course in reaching the goal. In particular situations, even
  3669. those of us with the goal of building a world where all published
  3670. software is Free Software realize that full copyleft does not best
  3671. serve us. The GNU Lesser General Public License (``GNU LGPL'') was
  3672. designed as a solution for such situations.
  3673. The Lesser General Public License is sometimes described as a ``weak copyleft''
  3674. license, because code licensed under LGPL's terms can be combined with code
  3675. under non-free licenses, and is sometimes used in that fashion.
  3676. \section{The First LGPL'd Program}
  3677. The first example that FSF encountered where such altered tactics were
  3678. needed was when work began on the GNU C Library. The GNU C Library would
  3679. become (and today, now is) a drop-in replacement for existing C libraries.
  3680. On a Unix-like operating system, C is the lingua franca and the C library
  3681. is an essential component for all programs. It is extremely difficult to
  3682. construct a program that will run with ease on a Unix-like operating
  3683. system without making use of services provided by the C library --- even
  3684. if the program is written in a language other than C\@. Effectively, all
  3685. user application programs that run on any modern Unix-like system must
  3686. make use of the C library.
  3687. By the time work began on the GNU implementation of the C libraries, there
  3688. were already many C libraries in existence from a variety of vendors.
  3689. Every proprietary Unix vendor had one, and many third parties produced
  3690. smaller versions for special purpose use. However, our goal was to create
  3691. a C library that would provide equivalent functionality to these other C
  3692. libraries on a Free Software operating system (which in fact happens today
  3693. on modern GNU/Linux systems, which all use the GNU C Library).
  3694. Unlike existing GNU application software, however, the licensing
  3695. implications of releasing the GNU C Library (``glibc'') under the GPL were
  3696. somewhat different. Applications released under the GPL would never
  3697. themselves become part of proprietary software. However, if glibc were
  3698. released under the GPL, it would require that any application distributed for
  3699. the GNU/Linux platform be released under the GPL\@.
  3700. Since all applications on a Unix-like system depend on the C library, it
  3701. means that they must link with that library to function on the system. In
  3702. other words, all applications running on a Unix-like system must be
  3703. combined with the C library to form a new whole work that is
  3704. composed of the original application and the C library. Thus, if glibc
  3705. were GPL'd, each and every application distributed for use on GNU/Linux
  3706. would also need to be GPL'd, since to even function, such applications
  3707. would need to be combined into larger works by linking with
  3708. glibc.
  3709. At first glance, such an outcome seems like a windfall for Free Software
  3710. advocates, since it stops all proprietary software development on
  3711. GNU/Linux systems. However, the outcome is a bit more subtle. In a world
  3712. where many C libraries already exist, many of which could easily be ported
  3713. to GNU/Linux, a GPL'd glibc would be unlikely to succeed. Proprietary
  3714. vendors would see the excellent opportunity to license their C libraries
  3715. to anyone who wished to write proprietary software for GNU/Linux systems.
  3716. The de-facto standard for the C library on GNU/Linux would likely be not
  3717. glibc, but the most popular proprietary one.
  3718. Meanwhile, the actual goal of releasing glibc under the GPL --- to ensure no
  3719. proprietary applications on GNU/Linux --- would be unattainable in this
  3720. scenario. Furthermore, users of those proprietary applications would also
  3721. be users of a proprietary C library, not the Free glibc.
  3722. The Lesser GPL was initially conceived to handle this scenario. It was
  3723. clear that the existence of proprietary applications for GNU/Linux was
  3724. inevitable. Since there were so many C libraries already in existence, a
  3725. new one under the GPL would not stop that tide. However, if the new C library
  3726. were released under a license that permitted proprietary applications
  3727. to link with it, but made sure that the library itself remained Free,
  3728. an ancillary goal could be met. Users of proprietary applications, while
  3729. they would not have the freedom to copy, share, modify and redistribute
  3730. the application itself, would have the freedom to do so with respect to
  3731. the C library.
  3732. There was no way the license of glibc could stop or even slow the creation
  3733. of proprietary applications on GNU/Linux. However, loosening the
  3734. restrictions on the licensing of glibc ensured that nearly all proprietary
  3735. applications at least used a Free C library rather than a proprietary one.
  3736. This trade-off is central to the reasoning behind the LGPL\@.
  3737. Of course, many people who use the LGPL today are not thinking in these
  3738. terms. In fact, they are often choosing the LGPL because they are looking
  3739. for a ``compromise'' between the GPL and the X11-style liberal licensing.
  3740. However, understanding FSF's reasoning behind the creation of the LGPL is
  3741. helpful when studying the license.
  3742. \section{What's the Same?}
  3743. Much of the text of the LGPL is identical to the GPL\@. As we begin our
  3744. discussion of the LGPL, we will first eliminate the sections that are
  3745. identical, or that have the minor modification changing the word
  3746. ``Program'' to ``Library.''
  3747. First, LGPLv2.1~\S1, the rules for verbatim copying of source, are
  3748. equivalent to those in GPLv2~\S1.
  3749. Second, LGPLv2.1~\S8 is equivalent GPLv2~\S4\@. In both licenses, this
  3750. section handles termination in precisely the same manner.
  3751. LGPLv2.1~\S9 is equivalent to GPLv2~\S5\@. Both sections assert that
  3752. the license is a copyright license, and handle the acceptance of those
  3753. copyright terms.
  3754. LGPLv2.1~\S10 is equivalent to GPLv2~\S6. They both protect the
  3755. distribution system of Free Software under these licenses, to ensure that
  3756. up, down, and throughout the distribution chain, each recipient of the
  3757. software receives identical rights under the license and no other
  3758. restrictions are imposed.
  3759. LGPLv2.1~\S11 is GPLv2~\S7. As discussed, it is used to ensure that
  3760. other claims and legal realities, such as patent licenses and court
  3761. judgments, do not trump the rights and permissions granted by these
  3762. licenses, and requires that distribution be halted if such a trump is
  3763. known to exist.
  3764. LGPLv2.1~\S12 adds the same features as GPLv2~\S8. These sections are
  3765. used to allow original copyright holders to forbid distribution in
  3766. countries with draconian laws that would otherwise contradict these
  3767. licenses.
  3768. LGPLv2.1~\S13 sets up the FSF as the steward of the LGPL, just as GPLv2~\S9
  3769. does for GPL. Meanwhile, LGPLv2.1~\S14 reminds licensees that copyright
  3770. holders can grant exceptions to the terms of LGPL, just as GPLv2~\S10
  3771. reminds licensees of the same thing.
  3772. Finally, the assertions of no warranty and limitations of liability are
  3773. identical; thus LGPLv2.1~\S15 and LGPLv2.1~\S16 are the same as GPLv2~\S11 and \S
  3774. 12.
  3775. As we see, the entire latter half of the license is identical.
  3776. The parts which set up the legal boundaries and meta-rules for the license
  3777. are the same. It is our intent that the two licenses operate under the
  3778. same legal mechanisms and are enforced precisely the same way.
  3779. We strike a difference only in the early portions of the license.
  3780. Namely, in the LGPL we go into deeper detail of granting various permissions to
  3781. create certain types of combinations, modifications and derivations.
  3782. The LGPL does not stretch the requirements as far as copyright law does regarding what
  3783. works must be relicensed under the same terms. Therefore, LGPL must
  3784. in detail explain which works can be proprietary. Thus, we'll see that the front matter of the LGPL is a
  3785. bit more wordy and detailed with regards to the permissions granted to
  3786. those who modify or redistribute the software.
  3787. \section{Additions to the Preamble}
  3788. Most of the LGPL's Preamble is identical, but the last seven paragraphs
  3789. introduce the concepts and reasoning behind creation of the license,
  3790. presenting a more generalized and briefer version of the story with which
  3791. we began our consideration of the LGPL\@.
  3792. In short, FSF designed the LGPL for those edge cases where the freedom of the
  3793. public can better be served by a more lax licensing system. FSF doesn't
  3794. encourage use of the LGPL automatically for any software that happens to be a
  3795. library; rather, FSF suggests that it only be used in specific cases, such
  3796. as the following:
  3797. \begin{itemize}
  3798. \item To encourage the widest possible use of a Free Software library, so
  3799. it becomes a de-facto standard over similar, although not
  3800. interface-identical, proprietary alternatives
  3801. \item To encourage use of a Free Software library that already has
  3802. interface-identical proprietary competitors that are more developed
  3803. \item To allow a greater number of users to get freedom, by encouraging
  3804. proprietary companies to pick a Free alternative for its otherwise
  3805. proprietary products
  3806. \end{itemize}
  3807. The LGPL's preamble sets forth the limits to which the license seeks to go in
  3808. chasing these goals. The LGPL is designed to ensure that users who happen to
  3809. acquire software linked with such libraries have full freedoms with
  3810. respect to that library. They should have the ability to upgrade to a newer
  3811. or modified Free version or to make their own modifications, even if they
  3812. cannot modify the primary software program that links to that library.
  3813. Finally, the preamble introduces two terms used throughout the license to
  3814. clarify between the different types of combined works: ``works that use
  3815. the library,'' and ``works based on the library.'' Unlike the GPL, the LGPL must
  3816. draw some lines regarding permissibly proprietary combined works. We do this here in this
  3817. license because we specifically seek to liberalize the rights afforded to
  3818. those who make combined works. In the GPL, we reach as far as copyright law
  3819. allows. In the LGPL, we want to draw a line that allows some derivative works
  3820. copyright law would otherwise prohibit if the copyright holder exercised
  3821. his full permitted controls over the work.
  3822. \section{An Application: A Work that Uses the Library}
  3823. In the effort to allow certain proprietary works and prohibit
  3824. others, the LGPL distinguishes between two classes of works:
  3825. ``works based on the library,'' and ``works that use the library.'' The
  3826. distinction is drawn on the bright line of binary (or runtime) combined
  3827. works and modified versions of source code. We will first consider the definition
  3828. of a ``work that uses the library,'' which is set forth in LGPLv2.1~\S5.
  3829. We noted in our discussion of GPLv2~\S3 (discussed in
  3830. Section~\ref{GPLv2s3} of this document) that binary programs when
  3831. compiled and linked with GPL'd software are covered as a whole by GPL\@.
  3832. This includes both linking that happens at compile-time (when
  3833. the binary is created) or at runtime (when the binary -- including library
  3834. and main program both -- is loaded into memory by the user). In GPL,
  3835. binary works are controlled by the terms of the license (in GPLv2~\S3),
  3836. and distributors of such binary works must release full
  3837. corresponding source\@.
  3838. The LGPL, by contrast, allows partial proprietarization of such binary works.
  3839. This scenario, defined in LGPL as ``a work that uses the library,'' works as
  3840. follows:
  3841. \newcommand{\workl}{$\mathcal{L}$}
  3842. \newcommand{\lplusi}{$\mathcal{L\!\!+\!\!I}$}
  3843. \begin{itemize}
  3844. \item A new copyright holder creates a separate and independent work,
  3845. \worki{}, that makes interface calls (e.g., function calls) to the
  3846. LGPL'd work, called \workl{}, whose copyright is held by some other
  3847. party. Note that since \worki{} and \workl{} are separate and
  3848. independent works, there is no copyright obligation on this new copyright
  3849. holder with regard to the licensing of \worki{}, at least with regard to
  3850. the source code.
  3851. \item The new copyright holder, for her software to be useful, realizes
  3852. that it cannot run without combining \worki{} and \workl{}.
  3853. Specifically, when she creates a running binary program, that running
  3854. binary must be a combined work, called \lplusi{}, that the user can
  3855. run.
  3856. \item Since \lplusi{} is a based on both \worki{} and \workl{},
  3857. the license of \workl{} (the LGPL) can put restrictions on the license
  3858. of \lplusi{}. In fact, this is what the LGPL does.
  3859. \end{itemize}
  3860. We will talk about the specific restrictions LGPLv2.1 places on ``works
  3861. that use the library'' in detail in Section~\ref{lgpl-section-6}. For
  3862. now, focus on the logic related to how the LGPLv2.1 places requirements on
  3863. the license of \lplusi{}. Note, first of all, the similarity between
  3864. this explanation and that in Section~\ref{separate-and-independent},
  3865. which discussed the combination of otherwise separate and independent
  3866. works with GPL'd code. Effectively, what LGPLv2.1 does is say that when a
  3867. new work is otherwise separate and independent, but has interface
  3868. calls out to an LGPL'd library, then it is considered a ``work that
  3869. uses the library.''
  3870. In addition, the only reason that LGPLv2.1 has any control over the licensing
  3871. of a ``work that uses the library'' is for the same reason that GPL has
  3872. some say over separate and independent works. Namely, such controls exist
  3873. because the {\em binary combination\/} (\lplusi{}) that must be created to
  3874. make the separate work (\worki{}) at all useful is a work based on
  3875. the LGPLv2.1'd software (\workl{}).
  3876. Thus, a two-question test that will help indicate if a particular work is
  3877. a ``work that uses the library'' under LGPLv2.1 is as follows:
  3878. \begin{enumerate}
  3879. \item Is the source code of the new copyrighted work, \worki{}, a
  3880. completely independent work that stands by itself, and includes no
  3881. source code from \workl{}?
  3882. \item When the source code is compiled, does it combine into a single work
  3883. with \workl{}, either by static (compile-time) or dynamic
  3884. (runtime) linking, to create a new binary work, \lplusi{}?
  3885. \end{enumerate}
  3886. If the answers to both questions are ``yes,'' then \worki{} is most likely
  3887. a ``work that uses the library.'' If the answer to the first question
  3888. ``yes,'' but the answer to the second question is ``no,'' then most likely
  3889. \worki{} is neither a ``work that uses the library'' nor a ``work based on
  3890. the library.'' If the answer to the first question is ``no,'' but the
  3891. answer to the second question is ``yes,'' then an investigation into
  3892. whether or not \worki{} is in fact a ``work based on the library'' is
  3893. warranted.
  3894. \section{The Library, and Works Based On It}
  3895. In short, a ``work based on the library'' could be defined as any
  3896. work based on the LGPL'd software that cannot otherwise fit the
  3897. definition of a ``work that uses the library.'' A ``work based on the
  3898. library'' extends the full width and depth of derivative, combined and/or
  3899. modified works under copyright law, in the same sense that the GPL does.
  3900. Most typically, one creates a ``work based on the library'' by directly
  3901. modifying the source of the library. Such a work could also be created by
  3902. tightly integrating new software with the library. The lines are no doubt
  3903. fuzzy, just as they are with GPL'd works, since copyright law gives us no
  3904. litmus test for determining if a given work is a derivative or otherwise a
  3905. modified version of another software program.
  3906. Thus, the test to use when considering whether something is a ``work
  3907. based on the library'' is as follows:
  3908. \begin{enumerate}
  3909. \item Is the new work, when in source form, a derivative and/or modified
  3910. work of, and/or a combined work with the LGPL'd work under
  3911. copyright law?
  3912. \item Is there no way in which the new work fits the definition of a
  3913. ``work that uses the library''?
  3914. \end{enumerate}
  3915. If the answer is ``yes'' to both these questions, then you most likely
  3916. have a ``work based on the library.'' If the answer is ``no'' to the
  3917. first but ``yes'' to the second, you are in a gray area between ``work
  3918. based on the library'' and a ``work that uses the library.''
  3919. You can also perform a similar same analysis through careful consideration of
  3920. the license text itself. LGPLv2~\S2(a) states that if a licensed work is a
  3921. software library (defined in LGPLv2~\S0 as ``a collection of software
  3922. functions and/or data prepared so as to be conveniently linked with
  3923. application programs (which use some of those functions and data) to form
  3924. executables''), you have permission to distribute modified versions only if
  3925. those versions are themselves libraries. LGPLv2.1 code can therefore not be
  3926. compliantly taken from its context in a library and placed in a non-library
  3927. modified version or work based on the work. For its part, LGPLv2~\S6 does
  3928. not provide an exception for this rule: a combination may be made of a
  3929. modified version of an LGPL'd library with other code, but the LGPL'd code
  3930. must continue to be structured as a library, and to that library the terms of
  3931. the license continue to apply.
  3932. Either way you view the rules, these issues are admittedly complicated.
  3933. Nevertheless, In our years of work with the LGPLv2.1, however, we have never
  3934. seen a work of software that was not clearly one or the other; the line is
  3935. quite bright. At times, though, we have seen cases where a particularly large
  3936. work in some ways seemed to be both to both a work that used the library and
  3937. a work based on the library. We overcame this problem by dividing the work
  3938. into smaller subunits. It was soon discovered that what we actually had were
  3939. three distinct components: the original LGPL'd work, a specific set of works
  3940. that used that library, and a specific set of works that were based on the
  3941. library. Once such distinctions are established, the licensing for each
  3942. component can be considered independently and the LGPLv2.1 applied to each
  3943. work as prescribed.
  3944. Finally, note though that, since the LGPLv2.1 can be easily upgraded to
  3945. GPLv2-or-later, in the worst case you simply need to comply as if the
  3946. software was licensed under GPLv2. The only reason you must consider the
  3947. question of whether you have a ``work that uses the library'' or a ``work
  3948. based on the library'' is when you wish to take advantage of the ``weak
  3949. copyleft'' effect of the Lesser GPL\@. If GPLv2-or-later is an acceptable
  3950. license (i.e., if you plan to copyleft the entire work anyway), you may find
  3951. this an easier option.
  3952. \section{Subtleties in Defining the Application}
  3953. In our discussion of the definition of ``works that use the library,'' we
  3954. left out a few more complex details that relate to lower-level programming
  3955. details. The fourth paragraph of LGPLv2.1~\S5 covers these complexities,
  3956. and it has been a source of great confusion. Part of the confusion comes
  3957. because a deep understanding of how compiler programs work is nearly
  3958. mandatory to grasp the subtle nature of what LGPLv2.1~\S5, \P 4 seeks to
  3959. cover. It helps some to note that this is a border case that we cover in
  3960. the license only so that when such a border case is hit, the implications
  3961. of using the LGPL continue in the expected way.
  3962. To understand this subtle point, we must recall the way that a compiler
  3963. operates. The compiler first generates object code, which are the binary
  3964. representations of various programming modules. Each of those modules is
  3965. usually not useful by itself; it becomes useful to a user of a full program
  3966. when those modules are {\em linked\/} into a full binary executable.
  3967. As we have discussed, the assembly of modules can happen at compile-time
  3968. or at runtime. Legally, there is no distinction between the two --- both
  3969. create a modified version of the work by copying and combining portions of one work and
  3970. mixing them with another. However, under LGPL, there is a case in the
  3971. compilation process where the legal implications are different.
  3972. To understand this phenomenon, we consider that a ``work that uses the
  3973. library'' is typically one whose final binary is a work based on the Program,
  3974. but whose source is not. However, sometimes, there
  3975. are cases where the object code --- that intermediate step between source
  3976. and final binary --- is a work created by copying and modifying code
  3977. from the LGPL'd software.
  3978. For efficiency, when a compiler turns source code into object code, it
  3979. sometimes places literal portions of the copyrighted library code into the
  3980. object code for an otherwise separate independent work. In the normal
  3981. scenario, the final combined work would not be created until final assembly and
  3982. linking of the executable occurred. However, when the compiler does this
  3983. efficiency optimization, at the intermediate object code step, a
  3984. combined work is created.
  3985. LGPLv2.1~\S5\P4 is designed to handle this specific case. The intent of
  3986. the license is clearly that simply compiling software to ``make use'' of
  3987. the library does not in itself cause the compiled work to be a ``work
  3988. based on the library.'' However, since the compiler copies verbatim,
  3989. copyrighted portions of the library into the object code for the otherwise
  3990. separate and independent work, it would actually cause that object file to be a
  3991. ``work based on the library.'' It is not FSF's intent that a mere
  3992. compilation idiosyncrasy would change the requirements on the users of the
  3993. LGPLv2.1'd software. This paragraph removes that restriction, allowing the
  3994. implications of the license to be the same regardless of the specific
  3995. mechanisms the compiler uses underneath to create the ``work that uses the
  3996. library.''
  3997. As it turns out, we have only once had anyone worry about this specific
  3998. idiosyncrasy, because that particular vendor wanted to ship object code
  3999. (rather than final binaries) to their customers and was worried about
  4000. this edge condition. The intent of clarifying this edge condition is
  4001. primarily to quell the worries of software engineers who understand the
  4002. level of verbatim code copying that a compiler often does, and to help
  4003. them understand that the full implications of LGPLv2.1 are the same regardless
  4004. of the details of the compilation progress.
  4005. \section{LGPLv2.1~\S6 \& LGPLv2.1~\S5: Combining the Works}
  4006. \label{lgpl-section-6}
  4007. Now that we have established a good working definition of works that
  4008. ``use'' and works that ``are based on'' the library, we will consider the
  4009. rules for distributing these two different works.
  4010. The rules for distributing ``works that use the library'' are covered in
  4011. LGPLv2.1~\S6\@. LGPLv2.1~\S6 is much like GPLv2~\S3, as it requires the release
  4012. of source when a binary version of the LGPL'd software is released. Of
  4013. course, it only requires that source code for the library itself be made
  4014. available. The work that ``uses'' the library need not be provided in
  4015. source form. However, there are also conditions in LGPLv2.1~\S6 to make sure
  4016. that a user who wishes to modify or update the library can do so.
  4017. LGPLv2.1~\S6 lists five choices with regard to supplying library source
  4018. and granting the freedom to modify that library source to users. We
  4019. will first consider the option given by \S~6(b), which describes the
  4020. most common way currently used for LGPLv2.1 compliance on a ``work that
  4021. uses the library.''
  4022. LGPLv2.1~\S6(b) allows the distributor of a ``work that uses the library'' to
  4023. simply use a dynamically linked, shared library mechanism to link with the
  4024. library. This is by far the easiest and most straightforward option for
  4025. distribution. In this case, the executable of the work that uses the
  4026. library will contain only the ``stub code'' that is put in place by the
  4027. shared library mechanism, and at runtime the executable will combine with
  4028. the shared version of the library already resident on the user's computer.
  4029. If such a mechanism is used, it must allow the user to upgrade and
  4030. replace the library with interface-compatible versions and still be able
  4031. to use the ``work that uses the library.'' However, all modern shared
  4032. library mechanisms function as such, and thus LGPLv2.1~\S6(b) is the simplest
  4033. option, since it does not even require that the distributor of the ``work
  4034. based on the library'' ship copies of the library itself.
  4035. LGPLv2.1~\S6(a) is the option to use when, for some reason, a shared library
  4036. mechanism cannot be used. It requires that the source for the library be
  4037. included, in the typical GPL fashion, but it also has a requirement beyond
  4038. that. The user must be able to exercise her freedom to modify the library
  4039. to its fullest extent, and that means recombining it with the ``work based
  4040. on the library.'' If the full binary is linked without a shared library
  4041. mechanism, the user must have available the object code for the ``work
  4042. based on the library,'' so that the user can relink the application and
  4043. build a new binary.
  4044. Almost all known LGPL'd distributions exercise either LGPLv2.1~\S6(a) or
  4045. LGPLv2.1~\S6(b). However, LGPLv2.1~\S6 provides three other options.
  4046. LGPLv2.1~\S6(c) allows for a written offer for CCS (akin to
  4047. \hyperref[GPLv2s3b]{GPLv2~\S3(b)}). CCS may also be distributed by network
  4048. under the terms of LGPLv2.1~\S6(c). Furthermore, under LGPLv2.1~\S6(e) the
  4049. distributor may ``verify'' that the user has already received, or at least
  4050. that the distributor has already sent to this particular user, the relevant
  4051. source\footnote{Policy motivations for LGPLv2.1~\S6(d) are unclear, but it
  4052. presumably intended to prevent requiring duplicate deliveries in ``whole
  4053. distribution'' situations.}.
  4054. Finally, LGPLv3~\S6 also requires that:
  4055. \begin{quote}
  4056. You must give prominent notice with each copy of the work that the
  4057. Library is used in it and that the Library and its use are covered by
  4058. this License. You must supply a copy of this License. If the work during
  4059. execution displays copyright notices, you must include the copyright
  4060. notice for the Library among them, as well as a reference directing the
  4061. user to the copy of this License.
  4062. \end{quote}
  4063. This is not identical to the roughly parallel requirements of GPLv2 and
  4064. GPLv3. Compliance requires slightly different measures with respect to the
  4065. ``credits'' or ``licenses'' or ``about'' screens in interactive programs.
  4066. \section{Distributing Works Based On the Library}
  4067. Essentially, ``works based on the library'' must be distributed under the
  4068. same conditions as works under full GPL\@. In fact, we note that
  4069. LGPLv2.1~\S2 is nearly identical in its terms and requirements to GPLv2~\S2.
  4070. There are, however, subtle differences and additions. For example not only
  4071. is CCS required (as would be with normal versions of GPL), but also the CCS
  4072. provided must enable a developer to regenerate the modified version of the
  4073. entire combined work, using with a modified version of the LGPL'd work (as a
  4074. replacement for the version a distributor provided). For example, LGPL'd
  4075. code is statically linked to a non-copyleft executable, the required source
  4076. code must also include sufficient material to split the distributed
  4077. executable and relink with a modified version of the library.
  4078. \section{And the Rest}
  4079. The remaining variations between the LGPL and the GPL cover the following
  4080. conditions:
  4081. \begin{itemize}
  4082. \item Allowing a licensing ``upgrade'' from the LGPL to the GPL\@ (in LGPLv2.1~\S3).
  4083. Note, however, LGPLv2.1~\S3 allows relicensing of works under its terms
  4084. instead under the terms of GPLv2-or-later. This provides, for example, a
  4085. pathway for those who do not want to use code under the requirements of
  4086. LGPLv2.1 to do so under GPLv2 or GPLv3 at their discretion.
  4087. \item Binary distribution of the library only, covered in LGPLv2.1~\S4,
  4088. which is effectively equivalent to LGPLv2.1~\S3
  4089. \item Creating aggregates of libraries that are separate and independent works from
  4090. each other, and distributing them as a unit (in LGPLv2.1~\S7)
  4091. \end{itemize}
  4092. Due to time constraints, we cannot cover these additional terms in detail,
  4093. but they are mostly straightforward. The key to understanding LGPLv2.1 is
  4094. understanding the difference between a ``work based on the library'' and a
  4095. ``work that uses the library.'' Once that distinction is clear, the
  4096. remainder of LGPLv2.1 is close enough to GPL that the concepts discussed in
  4097. our more extensive GPL unit can be directly applied.
  4098. \chapter{LGPLv3}
  4099. \label{LGPLv3}
  4100. LGPLv3 was designed to rectify architectural flaws in the GNU family of
  4101. licenses. Historically , LGPLv2.1 was a textual modification of GPLv2.
  4102. Reconciliation of licensing terms upon combination of LGPLv2.1'd and GPLv2'd
  4103. works is cumbersome, from a licensing bookkeeping perspective.
  4104. LGPLv3 redresses this historical problem through extensive use of
  4105. \hyperref[GPLv3s7]{GPLv3~\S7}'s exception architecture. LGPLv3 is therefore
  4106. a set of additional permission to GPLv3.
  4107. %FIXME: harken back to policy motivations of LGPL and how GPLv3 as a whole is
  4108. %always an option.
  4109. \section{Section 0: Additional Definitions}
  4110. LGPLv3~\S0 defines the ``Library'' -- a work that presents one or more
  4111. interfaces at which a ``use'' can be made by an ``Application.'' Class
  4112. inheritance is ``deemed'' a use of an interface. An ``Application,'' which is
  4113. other program code using one or more ``Library'' interfaces can be combined
  4114. with the code on the other side of the interfaces it uses to form a
  4115. ``Combined Work.''
  4116. \section{LGPLv3~\S1: Exception to GPLv3~\S3}
  4117. LGPLv3~\S1 excepts away the interference with use of LGPLv3 code as part of
  4118. ``effective technological measures'' of access limitation for other copyrighted
  4119. works provided otherwise by GPLv3~\S3.
  4120. \section{LGPLv3~\S2: Conveying Modified Versions}
  4121. LGPLv3~\S2 continues to require, as LGPLv2.1~\S2(d) requires, that the Library
  4122. not be modified to require keys, tokens, tables, or other global non-argument
  4123. data unrelated to function. This is again stated as a ``good faith effort''
  4124. requirement, but failure to cure on notice is strong evidence of the absence
  4125. of good faith. LGPLv3~\S2(b) permits removal of the permissions entirely (as
  4126. prescribed by GPLv3~\S7); however, such removal reduces the license of the
  4127. entire covered work back to pure GPLv3. Thus, exercising LGPLv3~\S2(b) as a
  4128. compliance alternative to LGPLv3~\S2(a) likely creates more compliance
  4129. obligations than it removes.
  4130. \section{LGPLv3~\S3: Object Code Incorporating Material from Library Header Files}
  4131. LGPLv3~\S3's front matter assures incorporation of smaller header files into
  4132. non-copylefted object code can proceed unimpeded. More complex
  4133. header files (those that do not meet the limitations provided in the
  4134. section), can still be incorporated into object code, a copy of appropriate
  4135. licensing information must accompany distribution (per LGPLv3~\S3(a--b).
  4136. %FIXME: talk about copyrightabilty lines and the like and why the ten line rule.
  4137. \section{LGPLv3~\S4: Combined Works}
  4138. LGPLv3~\S4 is the combination permission at the heart of LGPLv3. It restates
  4139. the license limitation provision of LGPLv2.1~\S2 to clarify that the terms on
  4140. the Combined Work may not prohibit user modification of the Library code, or
  4141. the debugging of such modifications to the Library code by means of whatever
  4142. reverse engineering is necessary.
  4143. LGPLv3~\S4(d)(0) contains the source provision requirement, for the Minimal
  4144. Corresponding Source, which ``means the Corresponding Source for the Combined
  4145. Work, excluding any source code for portions of the Combined Work that,
  4146. considered in isolation, are based on the Application, and not on the Linked
  4147. Version [of the Library]''. The alternative to the provision of source code is
  4148. distribution by way of the ``shared library'' mechanism under LGPLv3~\S4(d)(1),
  4149. described with respect to LGPLv2.1~\S6.
  4150. In addition, LGPLv3~\S4(e) requires the delivery of ``installation information''
  4151. required to install the modified version of the Library in ``user products''
  4152. under GPLv3~\S6. Where Library Minimal Corresponding Source is not made
  4153. available under LGPLv3~\S4(d)(1), LGPLv3~\S4(e) reaffirms that ``installation information''
  4154. must still be compliantly delivered under the terms of GPLv3~\S6.
  4155. All other provisions of GPLv3 are in force as previously described, and are
  4156. not excepted by the additional permission granted in LGPLv3.
  4157. If the distributor of the combined work intends not to distribute or offer
  4158. the source code of the LGPL'd components, the LGPL'd work must be separately
  4159. distributed (subject to source code delivery requirements as part of that
  4160. separate distribution) and packaged in a ``shared library'' mechanism, which
  4161. means that it:
  4162. \begin{quote}
  4163. \begin{enumerate}[label=4(d)(\arabic*):,ref=LGPLv3s4d\arabic*]
  4164. \item uses at run time a copy of the library already present on
  4165. the user's computer system, rather than copying library functions into
  4166. the executable, and
  4167. \item will operate properly with a modified version of
  4168. the library, if the user installs one, as long as the modified version is
  4169. interface-compatible with the version that the work was made with.
  4170. \end{enumerate}
  4171. \end{quote}
  4172. Taken all together, LGPLv3~\S4's primary implications for redistributors are
  4173. two-fold, as follows:
  4174. \begin{itemize}
  4175. \item If you create a program that links through a shared library mechanism to
  4176. a work that is separately distributed under LGPLv3, then you can
  4177. distribute the resultant program under a license of your choice and you
  4178. need not convey the LGPLv3'd work's source code. If you distribute the
  4179. library along with your program, or are the separate distributor of the
  4180. work in another context or as another product, you must distribute its
  4181. corresponding source under the terms of LGPLv3 or GPLv3-or-later.
  4182. \item If you choose to statically link or otherwise combine your program with
  4183. an LGPLv3'd work via mechanisms other than a shared library, you may choose your own license for the work provided the
  4184. license terms limitations for user modification, reverse engineering and
  4185. debugging are met, and given that the LGPL'd components are still
  4186. governed by LGPL's terms. You must offer or provide CCS for the LGPL'd components. The source code
  4187. material provided must be sufficient to regenerate the combined work with
  4188. a user-modified version of the LGPL'd components.
  4189. \end{itemize}
  4190. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  4191. % FIXME-LATER: There should be a chapter on GPL Exceptions generally.
  4192. % Here is some CC-By-SA text from another source that would make an
  4193. % acceptable introduction to a section on the GCC RTL Exception if such a
  4194. % chapter is written:
  4195. % This GCC Runtime Library Exception (``Exception'') is an additional
  4196. % permission as provided by Section 7 of GPLv3. The purpose of this Exception
  4197. % is to allow compilation of non-GPL (including proprietary) programs making
  4198. % use of the header files and runtime libraries covered by this Exception and
  4199. % containing code from the copyleft toolchain embedded by the compiler in the
  4200. % object code of the program as part of the compilation process. The GCC
  4201. % Runtime Library Exception covers any file that has a notice in its license
  4202. % headers stating that the exception applies.
  4203. % FIXME-LATER: end
  4204. \chapter{Integrating the GPL into Business Practices}
  4205. Since GPL'd software is now extremely prevalent through the industry, it
  4206. is useful to have some basic knowledge about using GPL'd software in
  4207. business and how to build business models around GPL'd software.
  4208. \section{Using GPL'd Software In-House}
  4209. As discussed in Sections~\ref{GPLv2s0} and~\ref{GPLv2s5} of this tutorial,
  4210. the GPL only governs the activities of copying, modifying and
  4211. distributing software programs that are not governed by the license.
  4212. Thus, in FSF's view, simply installing the software on a machine and
  4213. using it is not controlled or limited in any way by the GPL\@. Using Free
  4214. Software in general requires substantially fewer agreements and less
  4215. license compliance activity than any known proprietary software.
  4216. Even if a company engages heavily in copying the software throughout the
  4217. enterprise, such copying is not only permitted by GPLv2~\S\S1 and 3, but it is
  4218. encouraged! If the company simply deploys unmodified (or even modified)
  4219. Free Software throughout the organization for its employees to use, the
  4220. obligations under the license are very minimal. Using Free Software has a
  4221. substantially lower cost of ownership --- both in licensing fees and in
  4222. licensing checking and handling -- than the proprietary software
  4223. equivalents.
  4224. \section{Business Models}
  4225. \label{Business Models}
  4226. Using Free Software in house is certainly helpful, but a thriving
  4227. market for Free Software-oriented business models also exists. There is the
  4228. traditional model of selling copies of Free Software distributions.
  4229. Many companies make substantial revenue
  4230. from this model. Some choose this model because they have
  4231. found that for higher-end hardware, the profit made from proprietary
  4232. software licensing fees is negligible. The real profit is in the hardware,
  4233. but it is essential that software be stable, reliable and dependable, and
  4234. the users be allowed to have unfettered access to it. Free Software, and
  4235. GPL'd software in particular, is the right choice. For instance IBM can be
  4236. assured that proprietary versions of the their software will not exist to
  4237. compete on their hardware.
  4238. For example, charging a ``convenience fee'' for Free Software,
  4239. when set at a reasonable price (around \$60 or so), can produce some
  4240. profit. Even though Red Hat's system is fully downloadable on their
  4241. Web site, people still go to local computer stores and buy copies of their
  4242. box set, which is simply a printed version of the manual (available under
  4243. a Free license as well) and the Free Software system it documents.
  4244. \medskip
  4245. Custom support, service, and software improvement contracts
  4246. are the most widely used models for GPL'd software. The GPL is
  4247. central to their success, because it ensures that the code base
  4248. remains common, and that large and small companies are on equal
  4249. footing for access to the technology. Consider, for example, the GNU
  4250. Compiler Collection (GCC). Cygnus Solutions, a company started in the
  4251. early 1990s, was able to grow steadily simply by providing services
  4252. for GCC --- mostly consisting of new ports of GCC to different or new,
  4253. embedded targets. Eventually, Cygnus was so successful that
  4254. it was purchased by Red Hat where it remains a profitable division.
  4255. However, there are very small companies that compete in
  4256. this space. Modern industry demands the trust created by GPL protected
  4257. code-bases. Companies can cooperate on the software and
  4258. improve it for everyone. Meanwhile, companies who rely on GCC for their
  4259. work are happy to pay for improvements, and for ports to new target
  4260. platforms. Nearly all the changes fold back into the standard
  4261. versions, and those forks that exist remain freely available.
  4262. \medskip
  4263. \label{Proprietary Relicensing}
  4264. A final common business model that is perhaps the most controversial is
  4265. proprietary relicensing of a GPL'd code base. This is only an option for
  4266. software in which a particular entity holds exclusive rights to
  4267. relicense.\footnote{Entities typically hold exclusive relicensing rights
  4268. either by writing all the software under their own copyrights, collecting
  4269. copyright assignments from all contributors, or by otherwise demanding
  4270. unconditional relicensing permissions from all contributors via some legal
  4271. agreement} As discussed earlier in this tutorial, a copyright holder is
  4272. permitted under copyright law to license a software system under her
  4273. copyright as many different ways as she likes to as many different parties as
  4274. she wishes.
  4275. Some companies use this to their
  4276. financial advantage with regard to a GPL'd code base. The standard
  4277. version is available from the company under the terms of the GPL\@.
  4278. However, parties can purchase separate proprietary software licensing for
  4279. a fee.
  4280. This business model is at best problematic and at worst predatory because it means that the GPL'd code
  4281. base must be developed in a somewhat monolithic way, because volunteer
  4282. Free Software developers may be reluctant to assign their copyrights to
  4283. the company because it will not promise to always and forever license the
  4284. software as Free Software. Indeed, the company will surely use such code
  4285. contributions in proprietary versions licensed for fees.
  4286. \section{Ongoing Compliance}
  4287. GPL compliance is in fact a very simple matter --- much simpler than
  4288. typical proprietary software agreements and EULAs. Usually, the most
  4289. difficult hurdle is changing from a proprietary software mindset to one
  4290. that seeks to foster a community of sharing and mutual support. Certainly
  4291. complying with the GPL from a users' perspective gives substantially fewer
  4292. headaches than proprietary license compliance.
  4293. For those who go into the business of distributing {\em modified}
  4294. versions of GPL'd software, the burden is a bit higher, but not by
  4295. much. The glib answer is that by releasing the whole product as Free
  4296. Software, it is always easy to comply with the GPL. However,
  4297. admittedly to the dismay of FSF, many modern and complex software
  4298. systems are built using both proprietary and GPL'd components that are
  4299. clearly and legally separate and independent works, merely aggregated
  4300. together on the same device.
  4301. However, it sometimes is easier, quicker, and cheaper to simply
  4302. improve an existing GPL'd application than to start from scratch. In
  4303. exchange for this amazing benefit, the license requires that the modifier gives
  4304. back to the commons that made the work easier in the first place. It is a
  4305. reasonable trade-off and a way to help build a better world while also
  4306. making a profit.
  4307. Note that FSF does provide services to assist companies who need
  4308. assistance in complying with the GPL. You can contact FSF's GPL
  4309. Compliance Labs at $<$licensing@fsf.org$>$.
  4310. %FIXME-LATER: should have \tutorialpart
  4311. If you are particularly interested in matters of GPL compliance, we
  4312. recommend the next two parts, which include both recommendations on good
  4313. compliance and compliance case studies.
  4314. % =====================================================================
  4315. % END OF FIRST DAY SEMINAR SECTION
  4316. % =====================================================================
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