The Open Source Definition (Annotated)

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Version 1.9

The indented, italicized sections below appear as annotations to
the Open Source Definition (OSD) and are not a part of the OSD.
A plain version of the OSD without annotations can be found
here.

Introduction

Open source doesn't just mean access to the source code. The
distribution terms of open-source software must comply with
the following criteria:

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.

Rationale: 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

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.

Rationale: 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 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.

Rationale: 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

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.

Rationale: 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

The license must not discriminate against any person or group
of persons.

Rationale: 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.

Some countries, including the United States, have export restrictions for
certain types of software. An OSD-conformant license may warn licensees of
applicable restrictions and remind them that they are obliged to obey the
law; however, it may not incorporate such restrictions itself.

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.

Rationale: 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

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.

Rationale: 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

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.

Rationale: This clause forecloses yet another class of license traps.

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.

Rationale: Distributors of open-source software have the right
to make their own choices about their own software.

Yes, the GPL is conformant with this requirement. Software linked
with GPLed libraries only inherits the GPL if it forms a single work,
not any software with which they are merely distributed.

*10. License Must Be Technology-Neutral

No provision of the license may be predicated on any individual
technology or style of interface.

Rationale: This provision is aimed specifically at licenses
which require an explicit gesture of assent in order to establish a
contract between licensor and licensee. Provisions mandating so-called
"click-wrap" may conflict with important methods of software distribution
such as FTP download, CD-ROM anthologies, and web mirroring; such
provisions may also hinder code re-use. Conformant licenses must allow
for the possibility that (a) redistribution of the software will
take place over non-Web channels that do not support click-wrapping of
the download, and that (b) the covered code (or re-used portions of
covered code) may run in a non-GUI environment that cannot support
popup dialogues.