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We classify a license according to certain key questions:
If you want help to choose a license, evaluate a license, or have any other questions about licenses, you can email us at <gnu@gnu.org>.
Here is a list of licenses that do qualify as free software licenses:
We urge you not to use the BSD license for software you write. However, there is no reason not to use programs that have been released under the BSD license.
It is risky to recommend use of ``the BSD license'', because confusion could easily occur and lead to use of the original flawed BSD license. To avoid this risk, you can suggest the X11 license instead.
We urge you not to use the license of Apache for software you write. However, there is no reason to avoid running programs that have been released under this license, such as Apache.
We urge you not to use the license of Zope for software you write. However, there is no reason to avoid running programs that have been released under this license, such as Zope.
This license contains complex and annoying restrictions on how to publish a modified version, including one requirement that falls just barely on the good side of the line of what is acceptable: that any modified file must have a new name.
The reason this requirement is acceptable for LaTeX is that LaTeX has a facility to allow you to map file names, to specify ``use file bar when file foo is requested''. With this facility, the requirement is merely annoying; without the facility, the same requirement would be a serious obstacle, and we would have to conclude it makes the program non-free.
The LPPL says that some files, in certain versions of LaTeX, may have additional restrictions, which could render them non-free. For this reason, it may take some careful checking to produce a version of LaTeX that is free software.
The LPPL makes the controversial claim that simply having files on a machine where a few other people could log in and access them in itself constitutes distribution. We believe courts would not uphold this claim, but it is not good for people to start making the claim.
Please do not use this license for any other project.
These comments are based on version 1.2 (3 Sep 1999) of the LPPL.
We recommend you use this license for any Perl package you write, to promote coherence and uniformity in the area of Perl. Outside of Perl, we urge you not to use this license; it is better to use just the GNU GPL.
This disjunctive license is a good choice if you want to make your package GPL-compatible and MPL-compatible. However you can also accomplish that by using the LGPL or the Guile license.
This license might be a good choice if you have been using the MPL, and want to change to a GPL-compatible license without subtracting any permission you have given for previous versions.
We recommend that you use QPL-covered software packages only when absolutely necessary, and certainly don't use the QPL for anything that you write.
Since the QPL is incompatible with the GNU GPL, you cannot take a GPL-covered program and Qt and link them together, no matter how.
However, if you have written a program that uses Qt, and you want to release your program under the GNU GPL, you can easily do that. You can resolve the conflict for your program by adding a notice like this to it:
As a special exception, you have permission to link this program with the Qt library and distribute executables, as long as you follow the requirements of the GNU GPL in regard to all of the software in the executable aside from Qt.You can do this, legally, if you are the copyright holder for the program. Add it in the source files, after the notice that says the program is covered by the GNU GPL.
Here is a list of some licenses that do not qualify as free software licenses. A non-free license is automatically incompatible with the GNU GPL.
Please note that this license is not the same as the Open Publication License. The practice of abbreviating ``Open Content License'' as ``OPL'' leads to confusion between them. For clarity, it is better not to use the abbreviation ``OPL'' for either license. It is worth spelling their names in full to make sure people understand what you say.
This creates a practical pitfall in using or recommending this license: if you recommend ``Use the Open Publication License but don't enable the options'', it would be easy for the second half of that recommendation to get forgotten; someone might use the license with the options, making a manual non-free, and yet think he is following your advice.
Likewise, if you use this license without either of the options to make your manual free, someone else might decide to imitate you, then change his mind about the options thinking that that is just a detail; the result would be that his manual is non-free.
Thus, while manuals published under this license do qualify as free documentation if neither license option was used, it is better to use the GNU Free Documentation License and avoid the risk of leading someone else astray.
Please note that this license is not the same as the Open Content License. These two licenses are frequently confused, as the Open Content License is often referred to as the "OPL".
Please send FSF & GNU inquiries & questions to gnu@gnu.org. There are also other ways to contact the FSF.
Please send comments on these web pages to webmasters@www.gnu.org, send other questions to gnu@gnu.org.
Copyright (C) 1999,2000 Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA
Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.
Updated: 10 Aug 2000 bkuhn