LaTeX Project Public License

LaTeX Project Public License
Name	LaTeX Project Public License
Version	1.3c
Author	LaTeX Project
Publisher	LaTeX Project
Published	2005-12-01
Website	https://www.latex-project.org/lppl/

LaTeX Project Public License. The LaTeX Project Public License is a copyleft license specifically crafted for the LaTeX typesetting system and its associated software. Developed and maintained by the LaTeX Project, it is recognized as a free software license by the Free Software Foundation and is also approved by the Open Source Initiative. The license is designed to ensure the integrity of the LaTeX system while allowing for modification and distribution, balancing the needs of collaborative development with the stability of the core software.

History and development

The license was created by the LaTeX Project, the organization founded by Leslie Lamport and later stewarded by developers like Frank Mittelbach, to address the unique needs of the LaTeX ecosystem. Its development was influenced by the desire to maintain the consistency and reliability of documents processed by LaTeX, a concern stemming from the system's widespread use in academic and scientific publishing. The drafting process considered existing licenses like the GNU General Public License but aimed to solve specific problems of modular software where components could be independently modified. Key figures in its evolution included members of the TeX Users Group and the broader community contributing to the CTAN archive.

License terms and conditions

The license grants users the rights to use, study, copy, modify, and distribute the software, consistent with principles upheld by the Free Software Foundation. A distinctive requirement is that modified files must be renamed, a provision intended to prevent conflicts where an altered component could break a downstream document. It mandates that distributed works carry prominent notices of any changes, ensuring users are aware of modifications from the standard version maintained by the LaTeX Project. The license also includes specific clauses regarding the aggregation of works, influencing how packages from repositories like CTAN can be combined.

Comparison with other licenses

Unlike the GNU General Public License, which requires derivative works to be licensed under the same terms, this license uses a file-renaming rule to achieve a similar protective effect for the LaTeX core. It is more restrictive than permissive licenses such as the BSD licenses or the MIT License, which impose fewer conditions on modification. The license shares philosophical ground with the GNU Lesser General Public License in its application to software libraries but is tailored for a specific system. Its approach to modification control is often contrasted with that of the Apache License, used by projects like the Apache HTTP Server.

Usage and adoption

The license is the standard for the core LaTeX software distribution and for thousands of packages available on the CTAN archive. It is used by major TeX distributions including TeX Live and MiKTeX, ensuring a consistent legal framework across these platforms. Adoption extends to many academic institutions and publishers, such as those contributing to the American Mathematical Society, who rely on LaTeX for typesetting. The license's use is also common in projects integrated with other document preparation systems like ConTeXt.

Compatibility with other licenses

The Free Software Foundation considers the license compatible with the GNU General Public License, meaning GPL-licensed code can be combined with works under this license. This compatibility has facilitated the inclusion of LaTeX packages in larger free software projects distributed under the GPL. However, its unique file-renaming clause can create complexities when merging with code under more standard copyleft licenses. The Open Source Initiative approval signifies its alignment with the Open Source Definition, allowing it to coexist with other OSI-approved licenses in mixed projects.

Version history and updates

The license has undergone several revisions, with version 1.3 being a significant update to improve clarity and address community feedback. These updates have been managed by the LaTeX Project, often in consultation with the TeX Users Group and legal experts in open source software. Changes have focused on refining the modification clauses and ensuring the license remains enforceable in various jurisdictions, influenced by legal developments surrounding the GNU General Public License. Each version aims to maintain the license's core goal of protecting the integrity of the LaTeX system while supporting the collaborative model of the CTAN repository.

Category:Free software licenses Category:LaTeX Category:Copyleft licenses