The LaTeX Project Public License (LPPL) is a
software license
A software license is a legal instrument (usually by way of contract law, with or without printed material) governing the use or redistribution of software. Under United States copyright law, all software is copyright protected, in both source ...
originally written for the
LaTeX
Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latexes are found in nature, but synthetic latexes are common as well.
In nature, latex is found as a milky fluid found in 10% of all flowering plants (angiosperms ...
system. Software distributed under the terms of the LPPL can be regarded as
free software
Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, no ...
; however, it is not
copyleft
Copyleft is the legal technique of granting certain freedoms over copies of copyrighted works with the requirement that the same rights be preserved in derivative works. In this sense, ''freedoms'' refers to the use of the work for any purpose, ...
ed.
Besides the LaTeX base system, the LPPL is also used for most third-party LaTeX packages. Software projects other than LaTeX rarely use it.
Unique features of the license
The LPPL grew from
Donald Knuth
Donald Ervin Knuth ( ; born January 10, 1938) is an American computer scientist, mathematician, and professor emeritus at Stanford University. He is the 1974 recipient of the ACM Turing Award, informally considered the Nobel Prize of computer sc ...
's original license for TeX, which states that the source code for TeX may be used for any purpose but a system built with it can only be called 'TeX' if it strictly conforms to his canonical program. The incentive for this provision was to ensure that documents written for TeX will be readable for the foreseeable future and TeX and its extensions will still compile documents written from the early 1980s to produce output exactly as intended. Quoting Frank Mittelbach, the main author of the license: "LPPL attempts to preserve the fact that something like LaTeX is a language which is used for communication, that is if you write a LaTeX document you expect to be able to send it to me and to work at my end like it does at yours".
The most unusual part of the LPPL and equally the most controversial used to be the 'filename clause': ''You must not distribute the modified file with the filename of the original file.'' This feature made some people deny that the LPPL is a
free software license
A free-software license is a notice that grants the recipient of a piece of software extensive rights to modify and redistribute that software. These actions are usually prohibited by copyright law, but the rights-holder (usually the author) ...
. In particular the
Debian
Debian (), also known as Debian GNU/Linux, is a Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of D ...
community considered in 2003
excluding LaTeX from its core distribution because of this.
However, version 1.3 of the LPPL has weakened this restriction. Now it is only necessary that modified components identify themselves "clearly and unambiguously" as modified versions, both in the source and also when called in some sort of interactive mode. A name change of the work is still recommended, however.
In order to provide project continuity in the case that the copyright holder no longer wishes to maintain the work, maintenance can be passed on to another (or from maintainer to maintainer). This can either be declared by the copyright holder or, in the event that the copyright holder is no longer able to be contacted, by the individual taking over maintenance, with a three-month gap after their public intention to take over the maintenance. The modifying clause discussed above does not hold for the current maintainer of the work.
Copyright holders
The
LaTeX
Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latexes are found in nature, but synthetic latexes are common as well.
In nature, latex is found as a milky fluid found in 10% of all flowering plants (angiosperms ...
project holds the copyright for the text of the LPPL, but it does not necessarily hold the copyright for a work released under the LPPL. The author of the work holds copyright for the work, and is responsible for enforcing any violations of the license (or not).
Unlike the works released under the LPPL, the LPPL itself is not freely modifiable. While copying and distribution is allowed, changing the text of the LPPL is not. However, it may be used as a model for other licenses provided they do not reference the LPPL.
See also
*
Software using the LPPL (category)
References
External links
The LaTeX Project Public licenseOpen Source Initiative (OSI) approval of license
{{DEFAULTSORT:Latex Project Public License
Free and open-source software licenses
TeX