The Mozilla Public License Version 2.0 defines covered software as: (emphasis mine)

1.4. "Covered Software" means Source Code Form to which the initial Contributor has attached the notice in Exhibit A, the Executable Form of such Source Code Form, and Modifications of such Source Code Form, in each case including portions thereof.

Now, "covered software" is a crucial term for MPL-2 license, since the majority of the license text applies to the covered software only. So, I'd like to understand what this definition means, precisely.

Most of the comments or articles that I saw advise to put the notice from Exhibit A into each source file as a comment. As an alternative, the notice can be placed into some side-along file, however this practice is more questionable.

What I have not seen, however, is the discussion around the requirement in the definition that it must be the initial Contributor who adds the notice. The license defines a Contributor as

1.1. "Contributor" means each individual or legal entity that creates, contributes to the creation of, or owns Covered Software.

Then, presumably, "initial contributor" means the person who originally created the file in question.

So, the question is what happens if somebody other than the original author adds the notice into the file? I imagine there could be different scenarios of how this can happen:

  • The repository was initially licensed under a different license (say, MIT or GPL), and then the authors mutually agreed to switch to a different license.

  • The original author, not being legally savvy, forgot to put the notice into the file; and then another person decides to add the notice, as required by the terms of MPL-2.

  • The file is binary, so the text of the notice cannot be added. In order to comply with the license, the author adds a readme.txt file which says something like "All files in this directory have the following notice attached: <>". Perfectly reasonable so far, but imagine someone else adds a new file in this same directory. Seemingly, the notice contained in readme.txt applies, yet it was not the initial contributor who attached that notice.

In general, does it mean that looking at the license notice in the file is not sufficient to ascertain that the file is licensed under MPL-2 - one must check the file's history as well?

  • "The file is binary" that's a non-issue, since the licence requires that the notice be attached only to the "source code form". – MadHatter Jan 31 at 9:30
  • @MadHatter: Source code form can be a binary file format. Source code form means "the form of the work preferred for making modifications." – Bart van Ingen Schenau Jan 31 at 17:35
  • @BartvanIngenSchenau do you know of any MPL2-licensed software for which the preferred format for that is binary? – MadHatter Jan 31 at 21:59
  • @MadHatter "Binary" could mean any file which does not support adding comments. For example, "requirements.txt", or a config file, or images for a website, or csv data files, etc. – Pasha Jan 31 at 23:38
  • @Pasha thanks, but that's not the question; I understand what binary file formats are. The question is whether there exists any software under this licence where a binary format is the preferred format for making modifications, and if not, whether it is easily conceivable that such could exist. If the answer to both is no, then the third scenario above is not likely to arise. – MadHatter Feb 1 at 3:22

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