Free Software Licensing Alternatives
There are lots of different theories about freeware licenses out there, and therefore lots of things that can go in the Copying-Policy field of an LSM.
license codes that ibiblio's archiving tools recognize:
The codes below are listed from least restrictive to most.
Please note that it's not necessary to put a copyright in the Copying-Policy line. It's not even necessary to note that the software is copyrighted, because anything not explicitly placed in the public domain has a copyright.
We would prefer you not put special restrictions on commercial use. These make life difficult for CD-ROM distributors, prevent Linux from spreading as fast as it could, and confuse everybody. If you want to get paid for your effort, fine, sell your software. If you want to write free stuff, please make it free or shareware for everybody.
The Logic of Licenses: How To Pick One
Choosing license terms involves decisions about what, if any restrictions you want to put on what people do with your software.
If you want to make no restrictions at all, you should put your software in the public domain. An appropriate way to do this would be to include something like the following text at the head of each file:
Placed in public domain by J. Random Hacker, 1997. Share and enjoy!
If you do this, you are surrendering your copyright. Anyone can do anything they like with any part of the text. It doesn't get any freer than this. Very little free software is actually placed in the public domain, On Sunsite in mid-1997, only 3% of over 2600 software packages and documents announced PD status.
Copyright Status and Licenses
Anything that is not public domain has a copyright, possibly more than one. Under the Berne Convention (which has been U.S. law since 1978), the copyright does not have to be explicit. That is, the authors of a work hold copyright even if there is no copyright notice.
Who counts as an author can be very complicated, especially for software that has been worked on by many hands. This is why licenses are important. By setting out the terms under which material can be used, they grant rights to the users that protect them from arbitrary actions by the copyright holders.
In commercial software, the license terms are designed to protect the copyright. They're a way of granting a few rights to users while reserving as much legal territory is possible for the owner (the copyright holder). The copyright holder is very important, and the license logic so restrictive that the exact technicalities of the license terms are usually unimportant.
In free software, the situation is usually the exact opposite; the copyright exists to protect the license. The only rights the copyright holder always keeps are to enforce the license and to change the license terms of future versions. Otherwise, only a few rights are reserved and most choices pass to the user. In particular, the copyright holder cannot change the terms on a copy you already have. Therefore, in free software the copyright holder is almost irrelevant -- but the license terms are very important.
What Qualifies as Free Software
For licensing purposes, we can distinguish several different kinds of rights that a license may convey. Rights to copy and redistribute, rights to use, rights to modify for personal use, and rights to redistribute modified copies. A license may restrict or attach conditions to any of these rights.
The Debian Free Software Guidelines are the result of a great deal of thought about what makes software "free". Its constraints on licensing require that:
- An unlimited right to copy be granted.
- An unlimited right to use be granted.
- An unlimited right to modify for personal use be granted.
The guidelines prohibit restrictions on redistribution of modified binaries; this meets the needs of software distributors, who need to be able to ship working code without encumbrance. It allows authors to require that modified sources be redistributed as pristine sources plus patches, thus establishing the author's intentions and an "audit trail" of any changes by others.
This is as good a definition of "free software" as anyone has ever come up with. All of the standard licenses (MIT, BSD, Artistic, FRS, and GPL/LGPL) meet it (though some, like GPL, have other restrictions which you should understand before choosing it).
Note that licenses which allow noncommercial use only do not qualify as free-software licenses, even if they are decorated with "GPL" or some other standard license. They discriminate against particular occupations, persons, and groups. They make life too complicated for CD-ROM distributors and others trying to spread Linux commercially.
Varieties of Free Software Licensing
MIT or X Consortium license
The loosest kind of free-software license is one that grants unrestricted rights to copy, use, modify, and redistribute modified copies as long as a copy of the copyright and license terms is retained in all modified versions.
The MIT or X Consortium license has these terms. You can find a copy of a sample MIT-style license in flat-text form here.
Most "shareware" licenses have terms like this as well. They may request a donation, but they don't make it a condition of use.
The next most restrictive kind of license grants unrestricted rights to copy, use, modify, and redistribute modified copies as long as a copy of the copyright and license terms is retained in all modified versions, and an acknowledgement is made in advertising or documentation associated with the package.
The BSD license is the best-known license of this kind. You can find a flat-text copy here. Among parts of the free-software cullture that trace their lineages back to BSD Unix, this license is used even on a lot of free software that was written thousands of miles from Berkeley.
It is also not uncommon to find minor variants of the BSD license that change the copyright holder and omit the advertising requirement (making it effectively equivalent to the MIT license). These licenses are called "BSD-like".
Artistic License and FRS
The next most restrictive kind of license grants unrestricted rights to copy, use, and locally modify. It allows redistribution of modified binaries, but restricts redistribution of modified sources in ways intended to protect the interests of the authors and the free-software community.
The `Artistic License', devised for Perl and widely used in the Perl developer community, is of this kind. It requires modified files to contain "prominent notice" that they have been altered. It also requires people who redistribute changes to make them freely available and make efforts to propagate them back to the free-software community.
You can read a copy of the Artistic License here.
FRS is a license class made up for use in Sunsite's LSM files. It stands for "Freely Redistributable Software". An FRS license grants unrestricted rights to copy, use, and locally modify. It must grant the right to redistribute modified binaries, and must fulfill the other terms of the Debian license guidelines.
You should use `FRS' in the Copying-Policy code if your license restricts redistribution of modified binaries more closely than the Artistic license, but fulfills the Debian guidelines.
General Public License
The GNU General Public License (and its derivative, the Library GPL) is the single most widely used free-software license. Like the Artistic License, it allows redistribution of modified sources provided the modified files bear "prominent notice".
The GPL also requires that interactive programs licensed under GPL include a startup banner referring to the GPL. It also requires that any program containing parts that are under GPL be wholly GPLed. (The exact circumstances that trigger this requirement are not perfectly clear to everybody.)
These extra requirements actually make the GPL more restrictive than any of the other commonly-used licenses. (Larry Wall developed the Artistic License to avoid them while serving many of the same objectives.)
You can find a flat-text copy of the GPL here.