TUGboat, Volume 32 (2011), No. 1

83

Reflections on the history of the
LATEX Project Public License (LPPL) —A software license for LATEX and moreFrank Mittelbach
Abstract
In August 2010 the LATEX Project Public License(LPPL) was finally listed by the Open Source Initiative (OSI) as a free software license. This marks theendpoint of a long set of discussions around the TEX
community’s predominant license.
This article reflects on the history of the license,
the way it came about, and the reasons for its development and content. It explains why it was choseneven though alternative free licenses have been available at least from 1990 onwards.
Contents
1

Introduction: Why a special license?
83
1.1 The early days of the TEX community . . 83
1.2 Digression: The multicol license . . . . . 84
1.3 The GNU GPL — A new star on the horizon 84
1.4 The move from LATEX 2.09 to LATEX 2ε . . 85
1.5 Challenged by GPL evangelists . . . . . . 86
2 The evolution of the LPPL
87
2.1 An attempted cleanup . . . . . . . . . . . 87
2.2 Digression: The GNUTEX 0.x project . . . 87
2.3 The issue with unmaintained packages . . 88
2.4 The Debian dispute . . . . . . . . . . . . 88
2.5 OSI certification . . . . . . . . . . . . . . . 89
3 Conclusions89
3.1 Thanks . . . . . . . . . . . . . . . . . . . 90
A References90
B The LATEX Project Public License
91

1
1.1

Introduction: Why a special license?
The early days of the TEX community

When Donald Knuth in 1982 published the TEX
program it was one of the first, if not indeed thefirst, major program to be published as documented
source in its entirety. As such it forms an earlyexample of “free software”, well before this term
was more formally defined by Richard Stallman in
the free software movement, and well before one of
the most influential free software licenses — the GNU
GPL — was released in 1989.
Instead of a more elaborate license the source of
the TEX program contained (and still contains) theinteresting copyright and license information shownin Figure 1 on the following page. The motivation forthis small set of clauses was to ensure that documents
written for the TEX engine would be readable for theforeseeable future and indeed, TEX and its extensions

still compile documents written in the early 1980s
and produce output exactly as intended.
In those days, when the TEX community wasborn, the Internet was mainly restricted to academics
and used for knowledge sharing. Commercial aspects
hadn’t yet entered the space and spam wasn’t aknown phenomenon. As a result, not much got formalized and there was a general trust that others
would respect your ideas and would together help
in improving and developing them. People spentcountless hours on developing code and ideas andmade them available (typically free of charge) toothers. Most people didn’t bother with any formal
copyright notice, some had statements like “Copyright date name All rights reserved” while others
explicitly placed their work in the “public domain”.
Legally, all such works that were developed without granting explicit rights to others (e.g., by stating
those rights in a license, or by placing the material into the public domain), didn’t offer anybody
a right to work with the material, or to use it for
private or commercial purposes without explicitly
obtaining this right from the copyright holder. So
the simple copyright line “Copyright (C) 1992 by
Leslie Lamport” (from the old LATEX 2.09 sources)
could probably have been used to go after anybody
who made use of LATEX whether for their PhD or fortypesetting books for publication and sale.
But of course, nobody understood those lines inthis way. They were correctly understood1 as only
marking the intellectual ownership of the code butin the mind of the community and, I would think,in the minds of most if not all of the developers, not
as a mechanism to restrict any “proper” use of thematerial. Now the interesting part here is “proper”:
as most people spent considerable free time in developing their work, there was a base assumption in thecommunity (and other software communities) thatwhile such work should be freely available, those thatuse it should also in one way or the other contributeto the whole setup. Commercial use was frowned
upon by most as a way to take away the work of others for profit without a benefit for the community, so(not surprisingly) after a while works appeared that
explicitly stated “Freely usable for non-commercial
usage”, or “Commercial use not allowed” in addition
to a copyright notice.
Again, I would claim, back then nobody really
understood the implications and the legal situation
created with such statements — I certainly didn’t
when I developed my first packages for LATEX; I
1 In a legal sense this isn’t the correct interpretation asjust explained.

Reflections on the history of the LATEX Project Public License

84

TUGboat, Volume 32 (2011), No. 1% This program is copyright (C) 1982 by D. E. Knuth; all rights are reserved.
% Copying of this file is authorized only if (1) you are D. E. Knuth, or if% (2) you make absolutely no changes to your copy. (The WEB system provides% for alterations via an auxiliary file; the master file should stay intact.)% See Appendix H of the WEB manual for hints on how to install this program.
% And see Appendix A of the TRIP manual for details about how to validate it.
Figure 1: License of TEX, the program [3]simply copied such lines that I had seen in otherworks. Especially a statement like “No commercial
use allowed” was way over the top, since everybody
was happy if his or her package got used to produce
fine books or published articles and in most casesthat meant the work was commercially used.
1.2

Digression: The multicol license

The fact that such statements were not a dull sword
was something I learned to my surprise at one point
when I got approached by somebody for special extensions to multicol which took me quite some time
to implement. At several points in the discussions
I asked about the background for the requests andfinally got told that they had no intention of tellingme or anybody or making any of their part of thework available to others as they wanted to makemoney from it and that I should stop bothering
them. The way this was done got me slightly madand so I pointed out “heh, have you read the licensestatement on multicol about commercial usage notbeing allowed?” That made the email correspondence come to an abrupt halt for a moment and thena day or two later I had the company lawyers asking
for my phone number in Germany to discuss this andreach some settlement and license agreement. Well, I
was certainly young and naive back then2 so I didn’t
come out rich from this and probably wouldn’t have
either way, but it sure felt good that I had a lever tostop being taken for an absolute imbecile that could
be made to work for free under false premises.
This was about the first time I got some awareness about the importance and power of licenses aswell as of the fact that what was out there wasn’t
really what people intended. As I wasn’t interested
in making money from LATEX software and normally
would have wanted to use my stuff freely and free ofcharge, some refinements were really in order. Thus,
about to sell my soul and negotiate a special licensewith this company I had to come up with some ideaof an acceptable license (including a license fee). I
ended up with a sort of psychological experiment,
which was partly my coward’s way out of not wanting to deal with license fees and partly some genuine
2 I can report the first attribute has changed since then.

Frank Mittelbach

interest on what would happen. The result was perhaps the most curious license ever drawn up in that I
required for certain commercial usages of multicol
the licensee to determine the importance of it for hisor her circumstances and determine the license fee
from that.
I must say that the experiment as such was a success as it provided me with some interesting insights
into human psychology, though I can’t recommend it
to anybody who wants to make money from softwareor other works. Not that I want to imply that nolicense fees got paid: over the years I got a numberof nice presents, a book in Japanese (with a 100
Deutschmark note inside I nearly overlooked as it
was hidden and nowhere mentioned), and a few otherthings, so all in all, some pleasant surprises.
Somewhere around 2000 I changed the license
for multicol to the LPPL but to honor the history(and to continue the experiment) I kept the previous
license now toned down to a “Moral Obligation” sopeople are free to ignore it completely if they wish
to, while previously they were only free to set the fee
to zero by stating that this is the value they attach
to their use of multicol.3
1.3

The GNU GPL — A new star on
the horizon

Returning back to history: in 1989 Richard Stallman
published the first version of the GPL (General Public License) [1] for use with programs released as partof the GNU project. Richard intended the GPL tobecome a license that could be used with any free software project and in that he spectacularly succeeded(Wikipedia reports for 2007 a penetration of roughly
70% on major sites such as SourceForge.net). Since
its first introduction the use of the GPL in the free
software development communities increased steadily
to reach these impressive figures, especially in communities that were concerned with developing programs for individual use. The strong copyleft [2]provided by the GPL gave the programmer who used
the license the confidence that their work would benefit the whole world and any future development
3 Interested people can find the wording of this “Moral
Obligation” at the top of the multicol.sty or .dtx file [4]. It
is nearly identical to the earlier license statement.

TUGboat, Volume 32 (2011), No. 1

85

Our aim is that LATEX should be a system which can be trusted by users of all types to fulfill theirneeds. Such a system must be stable and well-maintained. This implies that it must be reasonably
easy to maintain (otherwise it will simply not get maintained at all). So here is a summary of ourbasic philosophy:
We believe that the freedom to rely on a widely-used standard for document interchange
and formatting is as important as the freedom to experiment with the contents of files.
We are therefore adopting a policy similar to that which Donald Knuth applies tomodifications of the underlying TEX system: that certain files, together with their names,
are part of the system and therefore the contents of these files should not be changed unlessthe following conditions are met:
• they are clearly marked as being no longer part of the standard system;• the name of the file is changed.
In developing this philosophy, and the consequent limitations on how modifications of the systemshould be carried out, we were heavily influenced by the following facts concerning the current
widespread and wide-ranging uses of the LATEX system.
1. LATEX is not just a document processing system; it also defines a language for document
exchange.
2. The standard document class files, and some other files, also define a particular formatting ofa document.
3. The packages that we maintain define a particular document interface and, in some cases,
particular formatting of parts of a document.
4. The interfaces between different parts of the LATEX system are very complex and it is therefore
very difficult to check that a change to one file does not affect the functionality of both thatfile and also other parts of the system not obviously connected to the file that has beenchanged.
Figure 2: Excerpts from the 1995 document “Modifying LATEX” [5]based on their code would remain free, rather thanbeing exploited by software companies that would
not return anything back to the community.
Within the TEX — and especially LATEX — community, however, the GPL played only a niche role.4
The community starship, the TEX program itself,came with its own very specific license “change myname if you want to change me” and many people (ifthey had bothered with some explicit license at all)
had adopted a similar approach or had used lines
like “freely usable for non-commercial purposes” asexplained earlier.
1.4

The move from LATEX 2.09 to LATEX 2εIn 1993 the LATEX project released a fundamentally
4 This situation has changed only marginally over time.
The majority of the packages for LATEX now use the LPPL for
their license, though many of the executable support programs
and some package use the GPL. More precisely, in October2010 we had 3849 products/packages listed on CTAN of which
592 (i.e., about 15%) were distributed under GPL and 1751
(i.e., about 45%) used the LPPL; the remainder (many ofthem fonts) had other licenses. And even if you just look at
non-LATEX works, this means the GPL is used by about 28% sostill significantly less than in other free software communities.

new version of LATEX. This new version (LATEX 2ε )for the first time got an explicit license in the formof a file called legal.txt which inside had the title“LATEX 2ε Copyright, Warranty and Distribution Restrictions”. One can think of this file as the very firstversion of the LPPL, though it wasn’t called that inthose days and it was a lot simpler than the licenseunder which LATEX is made available today.
Perhaps the most important aspect of it (which
later on also turned out to produce the biggest controversy) was the list of restrictions that apply when
producing changed versions of files from the LATEX
system, the most prominent being* You rename the file before you make anychanges to it.
This was directly modeled after Don Knuth’s license
for TEX and within the TEX community there wasbroad consensus this this was an adequate approachto balance between the freedom of the individual tobe able to reuse and modify the code if so desired
and the importance of LATEX as a communication language where people relied on being able to faithfully
reproduce a document written in one place elsewhere.

Reflections on the history of the LATEX Project Public License

86

TUGboat, Volume 32 (2011), No. 1
This license is an incomplete statement of the distribution terms for LATEX. As far as it goes,
it is a free software license, but incompatible with the GPL because it has many requirementsthat are not in the GPL.
This license contains complex and annoying restrictions on how to publish a modified
version, including one requirement that falls just barely on the good side of the line of what is
acceptable: that any modified file must have a new name.
The reason this requirement is acceptable for LATEX is that TEX has a facility to allow you
to map file names, to specify “use file bar when file foo is requested”. With this facility, therequirement is merely annoying; without the facility, the same requirement would be a serious
obstacle, and we would have to conclude it makes the program non-free.
The LPPL says that some files, in certain versions of LATEX, may have additional restrictions,which could render them non-free. For this reason, it may take some careful checking to
produce a version of LATEX that is free software.
Figure 3: Excerpts from Richard Stallman’s analysis of LPPL 1.2 [6]1.5

Challenged by GPL evangelists

While the TEX community was content with thestatus quo, people in the “GPL” world who used
TEX and LATEX felt uncomfortable with the licenses
in use and started to lobby for using the GPL within
the TEX community, as they felt that it was an
unjustified restriction to be forced to change a filename prior to making changes to it. The GPL doesn’tpose any such restriction: you can modify a workand distribute it without providing any easy visibleclue to its changed content.5
In essence two different world views on whatis “free software” and who should have what rights
clashed head-on for the first time. The GPL view islargely focused on the individual programmer, withthe purpose of the GPL being to offer him or her amaximum of rights on using and manipulating thework as well as ensuring that such rights can’t subsequently be taken away. On the other hand, the TEX
program license and later the LPPL acknowledged
the fact that TEX and LATEX defined a language
for communication and that the definition of sucha language needs to remain stable to serve as themeans of communication, i.e., it tried to achieve abalance between the individual right of a programmer to freely use the work and the community rightof the users of this language to rely on the work to befaithfully representing the language itself and thus
making communication possible.
5 This is an oversimplification, as the GPL requires that

“You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.”
However, in a context like LATEX where many files are loadedin the background, this would mean a user would need tocheck hundreds of files for modification information to ensurethat he or she is using the official versions when they getloaded by \usepackage etc. In contrast, if a file name change
in case of modifications is required then this problem vanishes
as the documents by themselves identify what they expect.

Frank Mittelbach

In response to suggestions that the modificationand distribution conditions for the files constituting
the LATEX system should be similar to those implied
by Version 2 of the GPL, the LATEX project teampublished the document “Modifying LATEX” [5] in an
attempt to clarify the position of the LATEX Project
team and to explain the rationale behind the license
decision. Some relevant excerpts from this document are shown in Figure 2 on the previous page.
The document also gave explicit guidance on how
to freely change a LATEX system in any way desired,either through customization or — if really needed —through producing a new system only based on the
LATEX code.
In 1995 Chris Rowley and I also met face to facewith Richard Stallman to discuss the Free Software
Foundation (FSF) concerns about the LATEX license
and as a result of this meeting and some subsequentemail discussions (in which we discussed a number of
aspects of the license and clarified or changed severalof them), Richard acknowledged LATEX (and its atthat point somewhat incomplete license statement)
as free software.6
Nevertheless, Richard made it very clear that
he didn’t like the approach taken by TEX and LATEX
and published his viewpoint as an analysis of thelicense on the GNU web pages [6] of which excerpts
are shown in Figure 3. (The current page states that
6 Looking through my email archives I found the following
beauty from the end of this discussion (the slanted text isfrom Richard, the reply was from some member of the LATEX
project team who shall go unnamed):

Ok, I believe that the methods you’ve
described for modifying LaTeX 2e are
adequate, so that LaTeX 2e can be considered
free software.
Hoorah hooray, let the jubilation commence!
LaTeX is free software after all!
— as it turned out, this conclusion was a bit premature.

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87

this analysis applies to LPPL 1.2, but the excerpt
more or less corresponds to the wording that was on
the GNU web site at the time.)
I’m not going to attempt to defeat his points
here, some are certainly well taken and others area matter of opinion and anyway, time has moved
on because the license text has greatly evolved fromthe legal.txt of 1993, via LPPL 1.0 in early 1999,
to LPPL 1.27 at the end of 1999, and ultimately to
LPPL 1.3 in 2003.
2

The evolution of the LPPL

2.1

An attempted cleanup

In the years between 1995 and 1999 a lot of new
software got written for LATEX and other flavorsof TEX. Most of this software was made available
through CTAN (the “Comprehensive TEX Archive
Network”) and regularly through TEX distributions
such as “TEX Live” or teTEX. One growing problem faced by these distributions was the number ofdifferent licenses under which all such packages inthe distribution were made available. LATEX core
had its legal.txt but everything else had its own
license and though there was the general belief that
all or most of it was free software, depending on the
viewpoint this wasn’t true. In many cases, different
strings were attached to individual packages so thata user of, say, LATEX would have been required tolook into every package used to understand what heor she was allowed to do with it.
So in 1998 or thereabouts, an attempt was madeto ease this situation: People wanted to produce a“free” TEX distribution for Debian, and to make sucha distribution in any way useful it was necessary to
ask for license changes in many packages or otherwise
exclude them as “non-free”. This was quite a heroic
act undertaken by a few individuals8 in their sparetime, as it often involved tracking down package
authors that had moved on to other pastures and hadcompletely forgotten that they had written some TEXor LATEX package in their former lives. (According
to Karl Berry this kind of work continues to this day,as legal terms unique to a given package continue
to be discovered, despite efforts at comprehensive
reviews.)
During that time the idea came up to turn
LATEX’s legal.txt into a generally usable license,
7 LPPL 1.1 lived for a very short time with only minor
differences in wording, but not content, from 1.2 — in essence
we had to get our act together and that took some attempts
and some time.
8 Names that stick out in my memory are Sebastian Rahtz
and Thomas Esser, though I’m sure others have helped too.

so that package authors could simply refer to it as
the license they use for their works. So this was theunderlying reason for the attempt to write up the
LPPL and in March 1999 version 1.0 of this license
was made publicly available. But as you can imagine,
writing a license is a nontrivial act, thus we had many
discussions on how to express the intent behind thelicense with the result that in fairly rapid succession(all still in 1999) versions 1.1 and 1.2 appeared. Looking back, the changes we made from legal.txt via
LPPL-1.0 to LPPL-1.1 to LPPL-1.2 were not all necessarily for the better, so some of Richard’s criticism
certainly holds true for these early attempts. What
we changed for LPPL-1.3, with the help of some morelegally trained people from Debian, was ultimately
considerably more significant.

2.2

Digression: The GNUTEX 0.x projectConcurrently, but unrelated to the efforts mentioned
earlier, the GNU project (that was also quite heavily
using TEX in the form of Texinfo for documentation)
got interested in shipping a “free TEX distribution”
with the GNU software and was looking at whichof the existing distributions might fit the bill — towhich the answer was none.
As Richard later explained to us, he became
exceedingly concerned that none of the major TEX
distributions could be distributed by GNU so he approached Thomas Esser (maintainer of the teTEX
distribution) to ask if it would be possible to separate the distribution into a free and a non-free part.
Thomas said yes, but that this would take quite sometime. So Richard asked within the GNU project if
there would be people to help Thomas with this.
At this point somebody came forward and suggested that he would be interested but would prefer
to build a new free distribution from scratch insteadof helping to update teTEX. Richard gave his okay
and as a result a TEX distribution called GNUTEX
got produced. As it turned out (not really a surprisegiven the license situation in the TEX world) the
first public beta of this distribution was very muchcrippled, but what made matters worse was that itcompletely ignored the existing license conditions of
the packages it included, for example, by not distributing the LATEX source documentation, i.e., its.dtx files.
When this became known to the LATEX project,David Carlisle tried to reason with the maintainer ofthis new distribution and asked him to update it. Unfortunately this resulted in very strange statements,
such as that he would remove files written by Davidand have people “write free replacements” for them,

Reflections on the history of the LATEX Project Public License

88

TUGboat, Volume 32 (2011), No. 1

continuing to bluntly disregard the LATEX license details that stated that LATEX had to be distributed asa whole.
It came to a climax with some messages making
personal comments against the LATEX developers,
and in particular David. At this time I joined thisdebate by asking Richard if this person was really
speaking for GNU, expressing my belief that if thatwas indeed the case, then this would show that thefree software movement was in parts in a very sorry
state. In a very personal email Richard replied with
an apology for the damage that has been done in
the name of the GNU project and in particular theverbal insults that some of the senior members of the
LATEX project team had to endure while defending
some core rights for which the GNU project andthe FSF were actually fighting. After some further
discussions, to get to the bottom of the dispute heensured that GNUTEX was taken off the archives andthat was the end of it.
What I took away with me from that episode
was that it is unfortunately very easy get carriedaway with the idea that “free” means that others
have no rights worth preserving.
2.3

The issue with unmaintained packages

By the turn of the century many people thought thatthe fight over licenses in the TEX world was over.
TEX and LATEX and many other packages had licenses
that were accepted as “free software licenses” by the
FSF and more and more authors of packages withquestionable licenses changed them or simply placed
their work under the LPPL from the beginning.
However, we now started to realize that the
LPPL in itself posed a problem for packages thatlost their author/maintainer because he or she lostinterest in the work or passed away as it sadly happened in some cases. As the LPPL required a namechange in case of modification, a new maintainer of apreviously unmaintained package couldn’t fix bugs orextend the functionality without changing its name.
In this way, perfectly good names could get lost for
the LATEX language — just because of the attempt topreserve the language integrity in the first place.
So in 2002 the idea was born to modify the LPPL
once more by including a maintenance clause thatwould allow a person under certain circumstances(normally when a work was orphaned) to take overmaintenance and in some sense ownership. The
clause was written in a way such that it was up to
the author of a work to allow or prevent this clause
to apply.
On the whole I believe that this proposed license
extension was a good idea as it further helped toFrank Mittelbach

stabilize LATEX as a reliable language. But it had an
unfortunate9 side effect that everybody interested infree software licenses started to take another look at
the LPPL.
The first person to ask was Richard, and I sent
him a draft of the intended changes and explained
their intentions. His reply was that he saw no issue
with any of them.
2.4

The Debian dispute

While a new draft of the LPPL that contained a firstversion of the maintainers clause got discussed on
the LATEX project list one of its subscribers, Claire
Connelly, explained that within the Debian community some people were unhappy about the LATEX
license and considered it nonfree (proposing to ban
LATEX from Debian distributions). She volunteered
to initiate a license review on the Debian-legal list
so that any issues with the license would be moved
from the level of vague rumor to a level of facts that
could be discussed intelligently.
However, a bit of a pity was that the first draftof LPPL-1.3 got presented which was not very clear,and thus added to the underlying misunderstandings
rather than helping to clear them up. For example, one of the initial reviews remarked: “so my
one-line summary of the license would be ‘We hateforking’ ” which doesn’t even remotely represent theintentions behind the license. Eventually, all suchmisunderstandings got resolved, but it took considerable effort. To be more precise, it took roughly 1600
messages (between July 2002 and June 2003) on thedebian-legal list and elsewhere to sort them out
and improve the wording to what in the end became
LPPL-1.3.
In retrospect it turned out to be fairly difficult
to identify the core reasons that led to this massive email exchange but from recollections there havebeen two major sources: textual and legal deficiencies
in the license as such, and a head-on clash between
different interpretations of “freedom”. As a result,the discussions on Debian-legal were essentially with
two only partly overlapping factions: a group ofpeople who seriously wanted to understand the intentions behind the license and who where interested
in providing guidance on how to improve it, while
ensuring that it would meet the DFSG (Debian Free
Software Guidelines), and a second group of people
largely concerned about the rights of the programmer to modify code ad lib without any restrictions.
The tenor here was “a requirement to rename is a
9 Or perhaps fortunate when looking at the final outcome.
However, if I would have known beforehand the amount ofwork that it took to get there, I would have let things lie.

TUGboat, Volume 32 (2011), No. 1

89

restriction” and therefore unacceptable. In otherwords, an important requirement for “freedom” wasthe ability to modify some work in situ. For many
situations this is an understandable requirement, e.g.,when fixing bugs or when extending functionality.
It does, however, become a bit blurry when modifications result in changing expected behavior. In
that case one can argue that there is also the rightof the recipient/user of the work to consider: to not
be deliberately misled.
As an example, an interesting thread within
the discussions spawned from a statement made by
Boris Veytsman: “I am FOR the freedom of speech.
However, I am against the freedom of my grocer tocall a 950g weight ‘a kilogram’.” The replies wereinteresting and ranged from the opinion that the Debian project has no intention of supporting deliberate
fraud (i.e., in this respect supporting his position) all
the way to the claim that this would be acceptablebehavior and needs to be supported in the spirit of
freedom. Clearly there isn’t any way to bridge thechasm between such widely different opinions witha license text and that was not attempted, thoughquite some energy was used on either side to argue
the respective positions.
Leaving aside the discussions around the more
extreme positions, the core point of dispute was theattempt of the LPPL to protect LATEX as a language
for interchange. By the nature of the beast thismeans acknowledging that in LATEX file names of
packages, classes, etc., are part of the (extensible)
LATEX language, i.e., each package extends or alters
the language and its name together with its functionality becomes part of LATEX when it is loaded.
That is, by \usepackage{name} the user requests a
certain package with a specific behavior upon which
his document then relies.
To continue the above analogy, when a user loads
the hypothetical package weights for typesetting grocery data then his document should not typeset 1kg
at some installations, but 950g at others, as thatwould render LATEX as a language useless.
In the end we settled for a toned down versionof this requirement: although the LATEX Project still
strongly recommends a name change in case of modifications, the license alternatively allows for producing
in situ modifications of components provided the derived work clearly and unambiguously identifies itself
as a modified version of the original component tothe user when used interactively in the same way theoriginal component would identify itself to the user
(Clause 6a of the license). In the case of a LATEX package that would typically be achievable through anappropriate change of the \ProvidesPackage decla-ration. However, the LATEX project team still recommends to use the name change approach and within
the TEX community this is the predominantly usedmethod. Whenever documents are intended to beexchanged this is the only safe way to ensure thatyour document typesets as intended and remains soover time. How powerful this approach is can beseen in the fact that with a few exceptions TEX andLATEX documents from the last two decades can be
still successfully typeset today.
Returning to the evolution of the license, on
June 18th 2003 the Debian legal community agreed
that LPPL 1.3 is a free software license with respect
to the DFSG guidelines. This marked the endpointof the active license development.
2.5

OSI certification

After the LPPL got accepted by Debian there wassome discussion about submitting it also for approvalthrough the Open Source Initiative, but effectively
we had run out of steam. It would have meant (another) round of formal submissions and most likely
discussions about wording and content and at least I
didn’t feel up to it at that time. But it was a somewhat naggingly open issue that the license wasn’t
certified by OSI, given that the LPPL codified theaccepted behavior in a large and active free softwarecommunity.
Fortunately, Will Robertson, a new member inthe LATEX project, took up that task and on therather nice date 09/09/09 approval from the OSI wassought in the category: “Licenses that are popularand widely used or with strong communities”.
As it turned out my fears of a repetition of the
DFSG experience were groundless; it took about twodozen email exchanges to get the license acceptedwithout any request for modification and only about
two months later on Wednesday, November 11, 2009
the OSI Board formally approved it [8]. It then tooknearly another year until the Open Source Initiative
updated their web site, but in August 2010 the license
finally appeared there [9].
3Conclusions

From the history it seems fairly obvious that there
are a good number of reasons why it is helpful to havea fairly uniform license landscape in a community likethe TEX world. Does it have to be the LPPL? That
question is less clear and as the discussions above
have shown a matter of opinion and controversy. But
on the whole I believe the answer is yes; the timeand effort was well spent and the community has
benefitted from it.

Reflections on the history of the LATEX Project Public License

90

TUGboat, Volume 32 (2011), No. 1

On the surface, languages like Perl or Python
have issues similar as LATEX. So why doesn’t LATEX
use the GPL as they do? I guess the answer lies in
the unique elements in the structure and usage of
LATEX (and perhaps its community?). It consists ofa very large and complete collection of third-party
packages in its standard form of distribution andall of this forms the language which the community
expects to be able to use interchangeably. The otherimportant difference is that for a library in Perl or
Python that implements a set of functions it is normally well understood what represents a “correct”
implementation of these functions, e.g., a time conversion function or a mathematical formula is either
implemented correctly or not — but it is not going
to be a matter of “taste”.
In the area of typography, however, “correctness”
has no reasonable definition and so it is not surprising that people have different opinion on what looks
good or how something should be improved. This isperfectly acceptable and in fact encouraged throughout the community but it needs to be channeledin order to maintain the other important aspect of
the language: support for interchange. And that issomething that the GPL and similar licenses aren’t
able to ensure, while the LPPL approaches, and, as
we think, resolved that issue adequately.
One of the commenters for the OSI review remarked, “I think this license is trying to create orenforce a policy for maintainership more than it concerns itself with copying & use/patent issues. I’m
not convinced that this is a good idea, but TEX hasan active community and if this license seems towork out for them, my level of concern isn’t so greatthat I would second-guess that aspect.” He is probably right, as in the TEX community the copying& use/patent issues play a minor role compared toresolving how to best maintain the language as awhole. Thus the idea of a maintainer and its rights
is quite prominent. We definitely think it helps inthat people know they are allowed to take over anorphaned work — it would probably happen less if itweren’t stated explicitly as a possibility.
Is the LPPL the best solution to the issues thata community like the TEX community encounters?
I guess not, but it is the best that we have beenable to come up with after many (perhaps too many)
hours and attempts.
3.1

Thanks

A number of people from the TEX community andfrom the Debian legal community have been instrumental in helping to make LPPL a better license andI would like to thank them all — in particular I wouldFrank Mittelbach

like to mention Jeff Licquia and Branden Robinsonfrom Debian legal10 with whom I had many fruitful
discussions over ways to improve it and shape in a
way that it properly expresses our intentions without conflicting with other people’s thoughts on whatcomprises a free software license.
From the TEX community I’d like to thank all of
my colleagues from the LATEX project team, in particular David Carlisle and Chris Rowley who shoulderedlarge proportions of the external discussions during
those years. And a heartfelt thanks to Will Robertson who single-handedly got the license OSI-approved
when the other team members had run out of steam
to even attempt it.
Many other people from the TEX community
contributed in one way or the other, be it on latex-l,debian-legal, or in private communication and it
is impossible to list them all. As a representativeof this huge group I should perhaps mention Boris
Veytsman who wrote over one hundred messages on
the subject during the debate with Debian.
Last not least I’d like to thank Richard Stallman
for initiating the first round of discussions and drawing our intentions to the flaws of the initial license
as well as opening at least my eyes to the complexityand difficulties behind free and open source software
licensing.
 Frank Mittelbach
LATEX Project
http://www.latex-project.org

A

References[1] The GNU GPL 1.0 can be found at: www.gnu.
org/licenses/old-licenses/gpl-1.0.txt[2] en.wikipedia.org/wiki/Copyleft[3] License for TEX at the top of mirror.ctan.
org/systems/knuth/dist/tex/tex.web[4] Moral obligation clause for the multicol
package at the top of mirror.ctan.org/
macros/latex/required/tools/multicol.dtx[5] The document “Modifying LATEX”: mirror.
ctan.org/macros/latex/doc/modguide.pdf[6] Comments on software licenses by the FSF:
www.gnu.org/licenses/license-list.html[7] lists.debian.org/debian-legal/[8] opensource.org/minutes2009111[9] www.opensource.org/licenses/lppl
10 There are a few more people from Debian legal should
perhaps be named but any list would naturally be incomplete. For those interested I suggest reading through thedebian-legal archives [7] from that time; you will find this alengthy but illuminating read in parts.

TUGboat, Volume 32 (2011), No. 1
B

91

The LATEX Project Public License
LPPL Version 1.3c 2008-05-04
Copyright 1999, 2002–2008 LATEX3 Project
Everyone is allowed to distribute verbatim copiesof this license document, but modification of it is
not allowed.

Preamble
The LATEX Project Public License (lppl) is the primary
license under which the LATEX kernel and the base LATEX
packages are distributed.
You may use this license for any work of which you
hold the copyright and which you wish to distribute.
This license may be particularly suitable if your work is
TEX-related (such as a LATEX package), but it is written
in such a way that you can use it even if your work isunrelated to TEX.
The section ‘whether and how to distributeworks under this license’, below, gives instructions,examples, and recommendations for authors who are
considering distributing their works under this license.
This license gives conditions under which a work may
be distributed and modified, as well as conditions underwhich modified versions of that work may be distributed.
We, the LATEX3 Project, believe that the conditions
below give you the freedom to make and distribute modified versions of your work that conform with whatever
technical specifications you wish while maintaining theavailability, integrity, and reliability of that work. If
you do not see how to achieve your goal while meetingthese conditions, then read the document ‘cfgguide.tex’and ‘modguide.tex’ in the base LATEX distribution forsuggestions.
Definitions
In this license document the following terms are used:
Work Any work being distributed under this License.
Derived Work Any work that under any applicablelaw is derived from the Work.
Modification Any procedure that produces a Derived
Work under any applicable law – for example, theproduction of a file containing an original file associated with the Work or a significant portion of sucha file, either verbatim or with modifications and/ortranslated into another language.
Modify To apply any procedure that produces a Derived Work under any applicable law.
Distribution Making copies of the Work available fromone person to another, in whole or in part. Distribution includes (but is not limited to) making
any electronic components of the Work accessible
by file transfer protocols such as ftp or http or
by shared file systems such as Sun’s Network File
System (nfs).
Compiled Work A version of the Work that has beenprocessed into a form where it is directly usable on
a computer system. This processing may include

using installation facilities provided by the Work,transformations of the Work, copying of componentsof the Work, or other activities. Note that modification of any installation facilities provided by theWork constitutes modification of the Work.
Current Maintainer A person or persons nominatedas such within the Work. If there is no such explicit
nomination then it is the ‘Copyright Holder’ under
any applicable law.
Base Interpreter A program or process that is normally needed for running or interpreting a part or
the whole of the Work.
A Base Interpreter may depend on external components but these are not considered part of theBase Interpreter provided that each external component clearly identifies itself whenever it is usedinteractively. Unless explicitly specified when applying the license to the Work, the only applicableBase Interpreter is a ‘LATEX-Format’ or in the caseof files belonging to the ‘LATEX-format’ a program
implementing the ‘TEX language’.
Conditions on Distribution and Modification
1. Activities other than distribution and/or modification of the Work are not covered by this license;
they are outside its scope. In particular, the act ofrunning the Work is not restricted and no requirements are made concerning any offers of support for
the Work.
2. You may distribute a complete, unmodified copyof the Work as you received it. Distribution of
only part of the Work is considered modification of
the Work, and no right to distribute such a Derived
Work may be assumed under the terms of this clause.
3. You may distribute a Compiled Work that has been
generated from a complete, unmodified copy of theWork as distributed under Clause 2 above, as longas that Compiled Work is distributed in such a
way that the recipients may install the Compiled
Work on their system exactly as it would have been
installed if they generated a Compiled Work directlyfrom the Work.
4. If you are the Current Maintainer of the Work, youmay, without restriction, modify the Work, thus
creating a Derived Work. You may also distributethe Derived Work without restriction, including
Compiled Works generated from the Derived Work.
Derived Works distributed in this manner by theCurrent Maintainer are considered to be updated
versions of the Work.
5. If you are not the Current Maintainer of the Work,you may modify your copy of the Work, thus creatinga Derived Work based on the Work, and compile
this Derived Work, thus creating a Compiled Work
based on the Derived Work.
6. If you are not the Current Maintainer of the Work,you may distribute a Derived Work provided thefollowing conditions are met for every component

Reflections on the history of the LATEX Project Public License

92of the Work unless that component clearly statesin the copyright notice that it is exempt from thatcondition. Only the Current Maintainer is allowed
to add such statements of exemption to a componentof the Work.
(a) If a component of this Derived Work can bea direct replacement for a component of theWork when that component is used with theBase Interpreter, then, wherever this component of the Work identifies itself to the userwhen used interactively with that Base Interpreter, the replacement component of this
Derived Work clearly and unambiguously identifies itself as a modified version of this component to the user when used interactively withthat Base Interpreter.
(b) Every component of the Derived Work contains prominent notices detailing the nature of
the changes to that component, or a prominent
reference to another file that is distributed aspart of the Derived Work and that contains acomplete and accurate log of the changes.
(c) No information in the Derived Work implies
that any persons, including (but not limitedto) the authors of the original version of theWork, provide any support, including (butnot limited to) the reporting and handling oferrors, to recipients of the Derived Work unless
those persons have stated explicitly that they
do provide such support for the Derived Work.
(d) You distribute at least one of the following
with the Derived Work:i. A complete, unmodified copy of the Work;if your distribution of a modified component is made by offering access to copy themodified component from a designatedplace, then offering equivalent access tocopy the Work from the same or somesimilar place meets this condition, eventhough third parties are not compelled tocopy the Work along with the modified
component;
ii. Information that is sufficient to obtain acomplete, unmodified copy of the Work.
7. If you are not the Current Maintainer of the Work,you may distribute a Compiled Work generated
from a Derived Work, as long as the Derived Workis distributed to all recipients of the Compiled Work,and as long as the conditions of Clause 6, above,
are met with regard to the Derived Work.
8. The conditions above are not intended to prohibit,
and hence do not apply to, the modification, by
any method, of any component so that it becomes
identical to an updated version of that componentof the Work as it is distributed by the Current
Maintainer under Clause 4, above.
9. Distribution of the Work or any Derived Work in analternative format, where the Work or that Derived
Frank Mittelbach

TUGboat, Volume 32 (2011), No. 1
Work (in whole or in part) is then produced byapplying some process to that format, does notrelax or nullify any sections of this license as they
pertain to the results of applying that process.
10. (a) A Derived Work may be distributed undera different license provided that license itself
honors the conditions listed in Clause 6 above,in regard to the Work, though it does nothave to honor the rest of the conditions in thislicense.
(b) If a Derived Work is distributed under a different license, that Derived Work must provide
sufficient documentation as part of itself toallow each recipient of that Derived Work tohonor the restrictions in Clause 6 above, concerning changes from the Work.
11. This license places no restrictions on works that are
unrelated to the Work, nor does this license place
any restrictions on aggregating such works with theWork by any means.
12. Nothing in this license is intended to, or may be
used to, prevent complete compliance by all parties
with all applicable laws.
No Warranty
There is no warranty for the Work. Except when otherwise stated in writing, the Copyright Holder provides
the Work ‘as is’, without warranty of any kind, either
expressed or implied, including, but not limited to, theimplied warranties of merchantability and fitness for aparticular purpose. The entire risk as to the quality andperformance of the Work is with you. Should the Workprove defective, you assume the cost of all necessary
servicing, repair, or correction.
In no event unless required by applicable law or
agreed to in writing will The Copyright Holder, or any
author named in the components of the Work, or any
other party who may distribute and/or modify the Workas permitted above, be liable to you for damages, including any general, special, incidental or consequential
damages arising out of any use of the Work or out of
inability to use the Work (including, but not limited to,loss of data, data being rendered inaccurate, or losses
sustained by anyone as a result of any failure of the Work
to operate with any other programs), even if the Copyright Holder or said author or said other party has beenadvised of the possibility of such damages.
Maintenance of The Work
The Work has the status ‘author-maintained’ if the Copyright Holder explicitly and prominently states near the
primary copyright notice in the Work that the Work can
only be maintained by the Copyright Holder or simply
that it is ‘author-maintained’.
The Work has the status ‘maintained’ if there is a
Current Maintainer who has indicated in the Work thatthey are willing to receive error reports for the Work (forexample, by supplying a valid e-mail address). It is not

TUGboat, Volume 32 (2011), No. 1

93

required for the Current Maintainer to acknowledge oract upon these error reports.
The Work changes from status ‘maintained’ to ‘unmaintained’ if there is no Current Maintainer, or the
person stated to be Current Maintainer of the work
cannot be reached through the indicated means of communication for a period of six months, and there are noother significant signs of active maintenance.
You can become the Current Maintainer of the Workby agreement with any existing Current Maintainer totake over this role. If the Work is unmaintained, you can
become the Current Maintainer of the Work through thefollowing steps:
1. Make a reasonable attempt to trace the Current
Maintainer (and the Copyright Holder, if the twodiffer) through the means of an Internet or similar
search.
2. If this search is successful, then enquire whether theWork is still maintained.
(a) If it is being maintained, then ask the Current Maintainer to update their communication data within one month.
(b) If the search is unsuccessful or no action to
resume active maintenance is taken by theCurrent Maintainer, then announce within thepertinent community your intention to takeover maintenance. (If the Work is a LATEX
work, this could be done, for example, by posting to comp.text.tex.)
3. (a) If the Current Maintainer is reachable andagrees to pass maintenance of the Work toyou, then this takes effect immediately uponannouncement.
(b) If the Current Maintainer is not reachable andthe Copyright Holder agrees that maintenanceof the Work be passed to you, then this takes
effect immediately upon announcement.
4. If you make an ‘intention announcement’ as described in 2b above and after three months yourintention is challenged neither by the Current Maintainer nor by the Copyright Holder nor by otherpeople, then you may arrange for the Work to bechanged so as to name you as the (new) Current
Maintainer.
5. If the previously unreachable Current Maintainer
becomes reachable once more within three months ofa change completed under the terms of 3b or 4, thenthat Current Maintainer must become or remain
the Current Maintainer upon request provided they
then update their communication data within one
month.
A change in the Current Maintainer does not, of itself,
alter the fact that the Work is distributed under the lppl
license.
If you become the Current Maintainer of the Work,
you should immediately provide, within the Work, aprominent and unambiguous statement of your status as
Current Maintainer. You should also announce your new
status to the same pertinent community as in 2b above.
Whether and How to Distribute Works underThis LicenseThis section contains important instructions, examples,and recommendations for authors who are considering
distributing their works under this license. These authors
are addressed as ‘you’ in this section.
Choosing This License or Another License
If for any part of your work you want or need to use
distribution conditions that differ significantly from thosein this license, then do not refer to this license anywhere
in your work but, instead, distribute your work under adifferent license. You may use the text of this license asa model for your own license, but your license should notrefer to the lppl or otherwise give the impression thatyour work is distributed under the lppl.
The document ‘modguide.tex’ in the base LATEX distribution explains the motivation behind the conditionsof this license. It explains, for example, why distributing
LATEX under the gnu General Public License (gpl) was
considered inappropriate. Even if your work is unrelated
to LATEX, the discussion in ‘modguide.tex’ may still be
relevant, and authors intending to distribute their works
under any license are encouraged to read it.
A Recommendation on Modification
Without Distribution
It is wise never to modify a component of the Work,even for your own personal use, without also meeting theabove conditions for distributing the modified component.
While you might intend that such modifications will never
be distributed, often this will happen by accident – you
may forget that you have modified that component; or
it may not occur to you when allowing others to accessthe modified version that you are thus distributing it
and violating the conditions of this license in ways that
could have legal implications and, worse, cause problems
for the community. It is therefore usually in your bestinterest to keep your copy of the Work identical withthe public one. Many works provide ways to control the
behavior of that work without altering any of its licensed
components.
How to Use This License
To use this license, place in each of the components ofyour work both an explicit copyright notice including
your name and the year the work was authored and/or
last substantially modified. Include also a statement thatthe distribution and/or modification of that component
is constrained by the conditions in this license.
Here is an example of such a notice and statement:

Reflections on the history of the LATEX Project Public License

94

TUGboat, Volume 32 (2011), No. 1%% pig.dtx%% Copyright 2005 M. Y. Name%
% This work may be distributed and/or modified under the% conditions of the LaTeX Project Public License, either version 1.3% of this license or (at your option) any later version.
% The latest version of this license is in%
http://www.latex-project.org/lppl.txt% and version 1.3 or later is part of all distributions of LaTeX% version 2005/12/01 or later.
%% This work has the LPPL maintenance status ‘maintained’.
%% The Current Maintainer of this work is M. Y. Name.
%% This work consists of the files pig.dtx and pig.ins% and the derived file pig.sty.
Given such a notice and statement in a file, theconditions given in this license document would apply,with the ‘Work’ referring to the three files ‘pig.dtx’,‘pig.ins’, and ‘pig.sty’ (the last being generated from‘pig.dtx’ using ‘pig.ins’), the ‘Base Interpreter’ referring to any ‘LATEX-Format’, and both ‘Copyright Holder’and ‘Current Maintainer’ referring to the person ‘M. Y.
Name’.
If you do not want the Maintenance section of lppl
to apply to your Work, change ‘maintained’ above into
‘author-maintained’. However, we recommend that you
use ‘maintained’ as the Maintenance section was addedin order to ensure that your Work remains useful to thecommunity even when you can no longer maintain andsupport it yourself.
Derived Works That Are Not Replacements
Several clauses of the lppl specify means to provide
reliability and stability for the user community. They
therefore concern themselves with the case that a Derived Work is intended to be used as a (compatible orincompatible) replacement of the original Work. If thisis not the case (e.g., if a few lines of code are reused for
a completely different task), then clauses 6b and 6d shallnot apply.

Frank Mittelbach

Important Recommendations
Defining What Constitutes the Work
The lppl requires that distributions of the Work containall the files of the Work. It is therefore important thatyou provide a way for the licensee to determine whichfiles constitute the Work. This could, for example, be
achieved by explicitly listing all the files of the Work near
the copyright notice of each file or by using a line suchas:
% This work consists of all files listed in manifest.txt.

in that place. In the absence of an unequivocal list it
might be impossible for the licensee to determine what
is considered by you to comprise the Work and, in sucha case, the licensee would be entitled to make reasonable
conjectures as to which files comprise the Work.