跟其他條款相比,從GNU通用公共許可證(GPL)到限制重重的著作權(Copyright),BSD許可證比較寬鬆,甚至跟公有領域更為接近。事實上,BSD許可證被認為是copycenter(中間版權),介乎標準的copyright與GPL的copyleft之間。"Take it down to the copy center and make as many copies as you want"[1]。可以說,GPL強迫後續版本必須一樣是自由軟體,BSD的後續版本可以選擇要繼續是BSD或其他自由軟體條款或封閉軟體等等。
BSD许可证的条款
许可证文本被认为遵循公有領域,所以可以不受限制地修改。为了满足个人或团体的需要,用户可以随意地将'Regents of the University of California'(加州大學董事会), 'University of California, Berkeley'(加州大学伯克利分校),以及'Regents'(董事会)替换成自己的名称。(参考中译附于英文原文后):
* Copyright (c) 1998, Regents of the University of California
* 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 University of California, Berkeley 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 THE REGENTS AND CONTRIBUTORS "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 THE REGENTS AND CONTRIBUTORS 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.}}
遵守BSD License的软件,允许用作商业用途,甚至可按照专属许可证进行再发布。比较著名的例子如微软产品中引入了BSD网络部分的代码,Mac OS X中使用了不少FreeBSD的组件。也可以将一部分遵照BSD许可证发布,另外一些采取其他许可证。事实上,BSD Unix早期就是这样的,其一部分是来自AT&T的专属内容。
* Copyright (c) 1982, 1986, 1990, 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 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.
* 4. Neither the name of the University 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 THE REGENTS AND CONTRIBUTORS ``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 THE REGENTS OR CONTRIBUTORS 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.}}
应理查德·斯托曼的请求,1999年7月22日,William Hoskins,也就是伯克利技术许可办公室的主管(director of the office of technology licensing for Berkeley),删除了BSD许可证的第三条。[3]
原来的许可证有时被称为“BSD-old”(老BSD)或“4-clause BSD”(四句版BSD),当前的BSD许可证有的被称为“BSD-new”(新BSD)、“revised BSD”(修订的BSD)或“3-clause BSD”(三句版BSD)。