GPL questions

[Peter]

I have a few questions about the GPL license.

Often there is a text at the top of every file that starts with "Foobar is free software: ...". Sometimes they don't mention the name of the software, "This program is free software: ...". If I take a file from project Foobar and put it into another project. Can I replace Foobar with the name of this other project? Do I have to state somehow that this software once was part of Foobar?

In the copyright notice there are a list of years. If a change is made to the file the current year is added. So what counts as a change? If I just change the formating I guess that is not a reason to add a year, or is it? What if I change a NULL to 0? What if I add an explicit cast instead of using an implicit cast? What if I change all int to char?

[charlie]

Yes, you may replace the name of the project and update the copyright year. The only stipulation of the GPL is that you re-release it under the GPL. You can change names, remove named contributors (unlike BSD or other licenses), update copyright (since the copyright now extends to the year you made changes) etc etc. It just has to stay GPL. That's a simplified view of the GPL but it's the core theme of the license.

[Julius]

However you may not "misrepresent" the authorship, e.g. you don't have to name the authors, but you can't pretend you have written it all yourself.

[Knitter]

If the software is GPL any change to it must result in a GPL compatible release. It doesn't matter if you change a space, you changed it .

If you take a file from a GPL project, you must release that file, with any changes you made to it, and any code that uses it in a GPL compatible license. You can mix licenses if they are compatible but keep in mind that such mixing is hard to maintain legal. You can change the text, and even remove any reference to the old project as long as you abide by GPL terms.

Misrepresenting a work is something that, usually, is covered by the laws of different countries and international treaties but sometimes also mention in licenses.

[charlie]

However you may not "misrepresent" the authorship, e.g. you don't have to name the authors, but you can't pretend you have written it all yourself.

And where in the license does it say this?

[charlie]

As far as I understand the GPL, it is perfectly legal to take a GPL program source, replace all "Copyright Foo" with "Copyright Bar" and redistribute it, as long as the GPL license is maintained.

[Knitter]

However you may not "misrepresent" the authorship, e.g. you don't have to name the authors, but you can't pretend you have written it all yourself.

And where in the license does it say this?

Some licenses state that but this falls a bit outside of the "license area", for example, in Portugal you can't remove the copyright and say that you did the program, it's illegal under the Portuguese laws that manage author's rights (there is no concept of copyright in Portugal as it exists in UK or USA).

As far as I understand the GPL, it is perfectly legal to take a GPL program source, replace all "Copyright Foo" with "Copyright Bar" and redistribute it, as long as the GPL license is maintained.

If you modify anything you must say so explicitly in order to comply with point 5. a) of the GNU GPL. Also, point 7 c) allows you to add the misrepresentation clause to the license, therefor you need not only look at the GNU GPL text but also to any other limitations imposed by the author.

It's not only a matter of maintaining the GPL license text you must make sure that you actually comply with its terms

[Peter]

Thank you all for the replies! I was not asking if I was allowed to remove the names of the copyright holders. Even if I'm allowed to do that it's probably not something I would do because it gets harder to know who owns the copyright. It was more the software name I was thinking about and from you it sounds like I can change it as I want, which make sense.

[amuzen]

GPLv3 seems to allow you to prohibit misrepresentation but it doesn't apply by default since it's one of the "Additional Terms". It probably exists for compatibility with those BSD style permissive licenses that require it.

Since the license boilerplate isn't a legal necessity, the year and project name aren't a big deal, I think. For practical reasons, it's still useful to have a boilerplate of some kind and mention the origin of the file.

[Julius]

However you may not "misrepresent" the authorship, e.g. you don't have to name the authors, but you can't pretend you have written it all yourself.

And where in the license does it say this?

Point 7 (additional terms), sub-point c)

"c) Prohibiting misrepresentation of the origin of that material, or requiring that modified versions of such material be marked in reasonable ways as different from the original version"

However it is an optional additional term, but quite a lot of programs include this, so it is normally save to assume that this clause applies.

Edit: should read a thread to the end before replying

[charlie]

I don't think it is in GPLv2 though.