On the Variability of the BSD and MIT Licenses

  • Trevor Maryka
  • Daniel M. German
  • Germán Poo-CaamañoEmail author
Conference paper
Part of the IFIP Advances in Information and Communication Technology book series (IFIPAICT, volume 451)


The MIT/X11 and the BSD are two of the most important family of Free and Open Source (FOSS) licenses. Because these licenses are to be inserted into the files that use it, and because they are expected to be changed by those who use them, their text has suffered alterations over time. Some of this variability is the result of licenses containing template fields which allow the license to be customized to include information such as the copyright holder name. Other variability can be attributed to changes in spelling, punctuation, and adding or removing conditions. This study empirically evaluated the extent that the BSD and MIT/X11 family of licenses are varied, and the manner and frequency in which license texts vary from the original definition. The study found that the BSD family has little variability, with a significant proportion fitting the common standard. The MIT/X11 family of licenses exhibited significantly more variation, with a higher propensity to customize the license text. In addition, the MIT/X11 license has spawned several specialized variants which likely constitute different legal meanings. Based on these findings, recommendations are proposed on what variability needs to be accommodated by the Software Package Data Exchange (SPDX) which is in the process of standardizing the allowed variability of both licenses.


Copyright Owner Copyright Holder Token Signature Open Source License Legal Meaning 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. 1.
    German, D., Penta, M.D.: A method for open source license compliance of java applications. IEEE Software 29(3), 58–63 (2012)CrossRefGoogle Scholar
  2. 2.
    German, D.M., Manabe, Y., Inoue, K.: A sentence-matching method for automatic license identification of source code files. In: 25nd IEEE/ACM International Conference on Automated Software Engineering (ASE 2010) (2010)Google Scholar
  3. 3.
    Gobeille, R.: The FOSSology project. In: MSR 2008: Proceedings of the 2008 International Conference on Mining Software Repositories, pp. 47–50. ACM, New York (2008)Google Scholar
  4. 4.
    Gonzalez-Barahona, J.M., Robles, G., Michlmayr, M., Amor, J.J., German, D.M.: Macro-level software evolution: a case study of a large software compilation. Empirical Software Engineering 14(3), 262–285 (2009)CrossRefGoogle Scholar
  5. 5.
    Lovejoy, J., Odence, P., Lamons, S.: Advancing the Software Package Data Exchange: An update. International Free and Open Source Software Law Review 2(2), 145–152 (2013)CrossRefGoogle Scholar
  6. 6.
    Rosen, L.: Open Source Licensing: Software Freedom and Intellectual Property Law. Prentice Hall (2004)Google Scholar
  7. 7.
    Stewart, K., Odence, P., Rockett, E.: Software Package Data Exchange (SPDX) Specification. International Free and Open Source Software Law Review 2(2), 191–196 (2010)Google Scholar

Copyright information

© IFIP International Federation for Information Processing 2015

Authors and Affiliations

  • Trevor Maryka
    • 1
  • Daniel M. German
    • 1
  • Germán Poo-Caamaño
    • 1
    Email author
  1. 1.University of VictoriaVictoriaCanada

Personalised recommendations