The LaTeX Project Public License (LPPL) is the license under which the base LaTeX distribution is distributed. As described below you may use this licence for any software that you wish to distribute.
It may be particularly suitable if your software is TeX related (such as a LaTeX package file) but it may be used for any software, even if it is unrelated to TeX.
To use this license, the files of your distribution should have an explicit copyright notice giving your name and the year, together with a reference to this license.
This license gives terms under which files of The Program may be distributed and modified. Individual files may have specific further constraints on modification, but no file should have restrictions on distribution other than those specified below.
This is to ensure that a distributor wishing to distribute a complete unmodified copy of The Program need only check the conditions in this file, and does not need to check every file in The Program for extra restrictions. If you do need to modify the distribution terms of some files, do not refer to this license, instead distribute The Program under a different license. You may use the parts of the text of LPPL as a model for your own license, but your license should not directly refer to the LPPL or otherwise give the impression that The Program is distributed under the LPPL.
There is no warranty for The Program, to the extent permitted by applicable law. Except when otherwise stated in writing, The Copyright Holder provides The Program `as is' without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. The entire risk as to the quality and performance of the program is with you. Should The Program prove 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 of the individual authors named in the source for The Program, be liable to you for damages, including any general, special, incidental or consequential damages arising out of any use of The Program or out of inability to use The Program (including but not limited to loss of data or data being rendered inaccurate or losses sustained by you or by third parties as a result of a failure of The Program to operate with any other programs), even if such holder or other party has been advised of the possibility of such damages.
Redistribution of unchanged files is allowed provided that all files that make up the distribution of The Program are distributed. In particular this means that The Program has to be distributed including its documentation if documentation was part of the original distribution.
The distribution of changed versions of certain files included in the The Program, and the reuse of code from The Program, are allowed under the following restrictions:
* You rename the file before you make any changes to it, unless the file explicitly says that renaming is not required. Any such changed files must be distributed under a license that forbids distribution of those files, and any files derived from them, under the names used by the original files in the distribution of The Program.
* If The Program includes an `error report address' so that errors may be reported to The Copyright Holder, or other specified addresses, this address must be changed in any modified versions of The Program, so that reports for files not maintained by the original program maintainers are directed to the maintainers of the changed files.
* You also distribute the unmodified version of the file or alternatively provide sufficient information so that the user of your modified file can be reasonably expected to be able to obtain an original, unmodified copy of The Program. For example, you may specify a URL to a site that you expect will freely provide the user with a copy of The Program (either the version on which your modification is based, or perhaps a later version).
* If The Program is intended to be used with, or is based on, LaTeX, then files with the following file extensions which have special meaning in LaTeX Software, have special modification rules under the license:
- Files with extension `.ins' (installation files): these files may not be modified at all because they contain the legal notices that are placed in the generated files.
- Files with extension `.fd' (LaTeX font definitions files): these files are allowed to be modified without changing the name, but only to enable use of all available fonts and to prevent attempts to access unavailable fonts. However, modified files are not allowed to be distributed in place of original files.
- Files with extension `.cfg' (configuration files): these files can be created or modified to enable easy configuration of the system. The documentation in cfgguide.tex in the base LaTeX distribution describes when it makes sense to modify or generate such files.
The above restrictions are not intended to prohibit, and hence do not apply to, the updating, by any method, of a file so that it becomes identical to the latest version of that file in The Program.
We believe that these requirements give you the freedom you to make modifications that conform with whatever technical specifications you wish, whilst maintaining the availability, integrity and reliability of The Program. If you do not see how to achieve your goal whilst adhering to these requirements then read the document cfgguide.tex in the base LaTeX distribution for suggestions.
Because of the portability and exchangeability aspects of systems like LaTeX, The LaTeX3 Project deprecates the distribution of non-standard versions of components of LaTeX or of generally available contributed code for them but such distributions are permitted under the above restrictions.
The document modguide.tex in the base LaTeX distribution details the reasons for the legal requirements detailed above. Even if The Program is unrelated to LaTeX, the argument in modguide.tex may still apply, and should be read before a modified version of The Program is distributed.
The individual files may bear additional conditions which supersede the general conditions on distribution and modification contained in this file. If there are any such files, the distribution of The Program will contain a prominent file that lists all the exceptional files.
* The conditions on *distribution* are the same for all the files. Thus a (re)distributor of a complete, unchanged copy of The Program need meet only the conditions in this file; it is not necessary to check the header of every file in the distribution to check that a distribution meets these requirements.
