BSD licenses: Difference between revisions

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The BSD daemon

BSD licenses represent a family of permissive free software licences. The original was used for the Berkeley Software Distribution, a Unix-like operating system for which the license is named. The original owners of BSD were the Regents of the University of California because BSD was first written at the University of California, Berkeley. The first version of the license was revised, and the resulting licenses are more properly called modified BSD licenses. Permissive licenses, sometimes with important differences pertaining to license compatibility, are referred to as "BSD-style licenses". Several BSD-like licenses, including the New BSD license, have been vetted by the Open Source Initiative as meeting their definition of open source.

The licenses have few restrictions compared to other free software licenses such as the GNU GPL or even the default restrictions provided by copyright, putting it relatively closer to the public domain. The BSD licenses have been referred to as copycenter, as a comparison to standard copyright and copyleft free software: "Take it down to the copy center and make as many copies as you want."

Terms

The text of the license is considered to be in the public domain and thus may be modified without restriction.

* Copyright (c) <year>, <copyright holder>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*     * Redistributions of source code must retain the above copyright
*       notice, this list of conditions and the following disclaimer.
*     * Redistributions in binary form must reproduce the above copyright
*       notice, this list of conditions and the following disclaimer in the
*       documentation and/or other materials provided with the distribution.
*     * Neither the name of the <organization> nor the
*       names of its contributors may be used to endorse or promote products
*       derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY <copyright holder> ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL <copyright holder> BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Proprietary software licenses compatibility

The BSD License allows proprietary commercial use, and for the software released under the license to be incorporated into proprietary commercial products. Works based on the material may even be released under a proprietary license (but still must maintain the license requirements). Some notable examples of this are the use of BSD networking code in Microsoft products, and the use of numerous FreeBSD components in Mac OS X.

It is possible for something to be distributed with the BSD License and some other license to apply as well. This was in fact the case with very early versions of BSD itself, which included proprietary material from AT&T.

UC Berkeley advertising clause

As originally distributed, the BSD license had an extra clause, requiring authors of all works deriving from a BSD-licensed work to include an acknowledgment of the original source. This is numbered as clause 3 in the original licence text:

* 3. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*      This product includes software developed by the University of
*      California, Berkeley and its contributors.

The GNU project called this clause "obnoxious", citing the requirement for 75 such acknowledgments when advertising a 1997 version of NetBSD. A large legal problem was that the advertising clause was incompatible with the terms of the GPL (which does not allow the addition of restrictions beyond those it already imposes) thus forcing a segregation of GNU and BSD software. The GNU project suggests people not use the phrase "BSD-style" licensing when they wanted to refer to an example of a non-copyleft license, in order to prevent inadvertent usage of the original BSD license.

Further, people who made changes to the source code tended to want to have their names added to the acknowledgement. This is problematic since with large numbers of people working on a single project (or for many separate projects in a software distribution), the advertising clause quickly created large and unwieldy acknowledgements.

This '4-clause' advertising version was removed from the official BSD license text on July 22, 1999 by William Hoskins, the director of the office of technology licensing for Berkeley, in response to a request from Richard Stallman. Other BSD distributions followed suit, but NetBSD still uses the original version of the license and many similar clauses remain in BSD derived code from other sources.

The original license is now sometimes called "BSD-old" or "4-clause BSD", while the current revision of the BSD license is sometimes referred to by the by names including "BSD-new", "revised BSD", or "3-clause BSD".

BSD-style licenses

Main article: Permissive free software licences

Several free or open source licenses that derive from or are similar to the BSD license are widely used:

• NetBSD still uses a 4-clause license equivalent to the original BSD license.
• A 2-clause BSD-like license also exists which deletes the third clause, prohibiting use of the copyright holder's name for endorsement purposes. Removal of that clause makes the license functionally equivalent to the MIT License. This is the only BSD-style license permitted for certain libraries included in KDE.
• FreeBSD also uses a 2-clause license with an additional statement at the end that the views of contributors are not the official views of the FreeBSD Project.
• FreeBSD also provides the FreeBSD Documentation License, a license similar to the subsequent BSD Documentation License that contains terms specific to documentation.
• The Massachusetts Institute of Technology (MIT)'s own MIT license is based on the BSD license, with most clauses removed and explicit permission for sublicensing and selling.
• OpenBSD uses a license modeled after the ISC license for all additional software created by the project, as it is functionally a two-clause BSD-styled license, with no additional clauses or consequences involved.
• The University of Illinois/NCSA Open Source License combines text from both the MIT and BSD licenses, and is equivalent to the 3-clause BSD license.
• The Xiph.Org Foundation uses the 3-clause license for the binary libraries of their different projects without significant differences from the New BSD license.
• Microsoft's Permissive License is a BSD-style software license in addition to a conditional, revokable royalty-free patent license.

See also

• Permissive and copyleft licences
• Glossary of legal terms in technology

External links

• BSD License Template
• The BSD License Problem (GNU Project)
• Materials about the Unix System Laboratories v. BSD case
• Marshall Kirk McKusick, Twenty Years of Berkeley Unix: From AT&T-Owned to Freely Redistributable, in: Open Sources: Voices from the Open Source Revolution, O'Reilly 1999