La definizione di Open Source serve a stabilire in modo preciso e inequivocabile quali siano le caratteristiche del «software libero» ( http://www.opensource.org).
The Open Source Definition (Version 1.0)
Open source doesn't just mean access to the source code. The distribution terms of an open-source program must comply with the following criteria:
1. Free Redistribution
The license may not restrict any party from selling or giving away the software as a component of an aggregate software distribution containing programs from several different sources. The license may not require a royalty or other fee for such sale.
2. Source Code
The program must include source code, and must allow distribution in source code as well as compiled form. Where some form of a product is not distributed with source code, there must be a well-publicized means of downloading the source code, without charge, via the Internet. The source code must be the preferred form in which a programmer would modify the program. Deliberately obfuscated source code is not allowed. Intermediate forms such as the output of a preprocessor or translator are not allowed.
3. Derived Works
The license must allow modifications and derived works, and must allow them to be distributed under the same terms as the license of the original software.
4. Integrity of The Author's Source Code.
The license may restrict source-code from being distributed in modified form only if the license allows the distribution of "patch files" with the source code for the purpose of modifying the program at build time. The license must explicitly permit distribution of software built from modified source code. The license may require derived works to carry a different name or version number from the original software.
5. No Discrimination Against Persons or Groups.
The license must not discriminate against any person or group of persons.
6. No Discrimination Against Fields of Endeavor.
The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research.
7. Distribution of License.
The rights attached to the program must apply to all to whom the program is redistributed without the need for execution of an additional license by those parties.
8. License Must Not Be Specific to a Product.
The rights attached to the program must not depend on the program's being part of a particular software distribution. If the program is extracted from that distribution and used or distributed within the terms of the program's license, all parties to whom the program is redistributed should have the same rights as those that are granted in conjunction with the original software distribution.
9. License Must Not Contaminate Other Software.
The license must not place restrictions on other software that is distributed along with the licensed software. For example, the license must not insist that all other programs distributed on the same medium must be open-source software.
10. Example Licenses.
The GNU GPL, BSD, X Consortium, and Artistic licenses are examples of licenses that we consider conformant to the Open Source Definition. So is the MPL.
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Bruce Perens wrote the first draft of this document as `The Debian Free Software Guidelines', and refined it using the comments of the Debian developers in a month-long e-mail conference in June, 1997. He removed the Debian-specific references from the document to create the `Open Source Definition'.
Rationale for the Open Source Definition
The intent of the Open Source Definition is to protect the open-source process - to ensure that software distributed under an open-source license will be available for independent peer review and continuous evolutionary improvement and selection, reaching levels of reliability and power no closed product can attain.
For the evolutionary process to work, we have to counter short-term incentives for people to stop contributing to the software gene pool. This means the license terms must prevent people from locking up software where very few people can see or modify it.
1. Free Redistribution
By constraining the license to require free redistribution, we eliminate the temptation to throw away many long-term gains in order to make a few short-term sales dollars. If we didn't do this, there would be lots of pressure for cooperators to defect.
2. Source Code
We require access to un-obfuscated source code because you can't evolve programs without modifying them. Since our purpose is to make evolution easy, we require that modification be made easy.
3. Derived Works
The mere ability to read source isn't enough to support independent peer review and rapid evolutionary selection. For rapid evolution to happen, people need to be able to experiment with and redistribute modifications.
4. Integrity of The Author's Source Code
Encouraging lots of improvement is a good thing, but users have a right to know who is responsible for the software they are using. Authors and maintainers have reciprocal right to know what they're being asked to support and protect their reputations.
Accordingly, an open-source license must guarantee that source be readily available, but may require that it be distributed as pristine base sources plus patches. In this way, "unofficial" changes can be made available but readily distinguished from the base source.
5. No Discrimination Against Persons or Groups.
In order to get the maximum benefit from the process, the maximum diversity of persons and groups should be equally eligible to contribute to open sources. Therefore we forbid any open-source license from locking anybody out of the process.
6. No Discrimination Against Fields of Endeavor.
The major intention of this clause is to prohibit license traps that prevent open source from being used commercially. We want commercial users to join our community, not feel excluded from it.
7. Distribution of License.
This clause is intended to forbid closing up software by indirect means such as requiring a non-disclosure agreement.
8. License Must Not Be Specific to a Product.
This clause forecloses yet another class of license traps.
9. License Must Not Contaminate Other Software.
People who want to use or redistribute open-source software have the right to make their own choices about their own software.