Permissive free software licence

A Permissive open source license (English original term permissive license ) is an open -source license, which allows a wider re-use of licensed content, as strict copyleft licenses such as the GNU General Public License. Such a license provides many of the same properties that provide other open source licenses. In contrast to non - permissive, so strict, copyleft licenses like the GPL can all derivatives and copies of the source code, which is under such a license, are published and distributed under terms and conditions which are more restrictive or have fundamentally different properties than the the original license. In other words, derivations of standing under a permissive license source code must not be released under the same license as the original code, but may for example be made into proprietary software.

Well-known examples permissive licenses are the MIT License and the BSD license.

Compared to Public Domain

Computer Associates Int'l v. Altai used the concept of a public domain (English Public Domain, all copyrights go to the general public on ) to refer to works that are very widespread, but among permission, on the contrary, work that deliberately are designated as public domain. Such licenses are not actually equivalent to the Public Domain.

Permissive licenses often arrange some limited duties, must be named like that of the original author ( attribution ). If a plant is actually in the public domain, so this is from a legal point of view not usually necessary, but naming the author of a work is considered eg in academia as an ethical duty.

GPL compatibility

Some permissive licenses contain clauses requiring the licensee to mention the original copyright in advertising for the derived product. These clauses are called advertising clauses. An example based on the PHP license: If released a product that was derived from PHP, so must always be mentioned that it is derived from PHP, especially in advertising for this new product. Licenses with advertising clause include the 4- claus -celled BSD license, the PHP license and the OpenSSL license. These licenses are, although they are permissive licenses ( as they do not prohibit proprietary published derivations ), incompatible with the much-used GPL ( prohibits such discharges, discharges of GPL works must be released under the GPL ).

Examples of permissive licenses without advertising clauses are the MIT license, the 3- claus -celled BSD License, zlib license and all versions of the Apache license, except version 1.0.

Some licenses prohibit derivative works, add a constraint for the reason which prohibits a Redistributor to introduce other or more restrictions. The purpose of such clauses is the banning of further distributing under the GPL or similar copyleft licenses. There are many examples of such licenses, such as the CDDL and MPL. Such restrictions make a license always incompatible with the BSD license.

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