This is the MIL-OSS Open Source Software (OSS) Frequently-Asked Questions (FAQ).

General Questions

Where can I get official information about open source software (OSS) in the U.S. Department of Defense (DoD)?

See the DoD Chief Information Officer (CIO) Free Open Source Software (FOSS) Communities of Interest (COI) site.  You can see there the official DoD policy memo "Clarifying Guidance Regarding Open Source Software (OSS)", a memorandum signed by David M. Wennergren on 16 October 2009.  It also has other useful information on open source software.

What are common definitions of the term "open source software"?

The 16 October 2009 memorandum from the DoD CIO, "Clarifying Guidance Regarding Open Source Software (OSS)", defines OSS as "software for which the human-readable source code is available for use, study, re-use, modification, enhancement, and re-distribution by the users of that software".

The Free Software Foundation (FSF)'s Free Software Definition defines the related term "Free software" as software in which the program's users have the "four essential freedoms":

• The freedom to run the program, for any purpose (freedom 0).
• The freedom to study how the program works, and change it so it does your computing as you wish (freedom 1). Access to the source code is a precondition for this.
• The freedom to redistribute copies so you can help your neighbor (freedom 2).
• The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.

The Open Source Initiative (OSI)'s Open Source Definition says that "Open source doesn't just mean access to the source code. The distribution terms of open-source software must comply with the following criteria..." where the criteria are:

1. Free Redistribution. The license shall 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 shall 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 obtaining the source code for no more than a reasonable reproduction cost preferably, downloading via the Internet without charge. 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 Restrict 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. License Must Be Technology-Neutral. No provision of the license may be predicated on any individual technology or style of interface.

All of these different definitions are attempts to clearly define the same basic concept of rights that recipients must receive with the software.

Where can I get an answer to my frequently-asked question (FAQ)?

The official DoD Open Source Software (OSS) FAQ has answers to many common OSS questions, and is publicly available.  If you have access to it, you can see more a more recent version of it on the Intellipedia article, Open Source Software (OSS) FAQ.

The Free Software Foundation (FSF)'s Frequently Asked Questions (FAQ) about the GNU Licenses has a lot of information, focusing on the GNU General Public License (GPL) and Lesser General Public License (LGPL).

The Open Source Definition (Annotated) explains the rationale for the requirements in the Open Source Initiative (OSI)'s open source definition

How can I suggest a new FAQ entry?

Send an email to David A. Wheeler, dwheeler (at) dwheeler (dot) com.  Include "xyzzy" in the subject line.