science

The Open Source Definition

The Open Source Definition is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand The Open Source Definition rather than just read about it. In short: The Open Source Definition (OSD) is a policy document published by the Open Source Initiative in 1998. Derived from the Debian Free Software Guidelines written by Bruce Perens, the OSD is the predominant standard for open-source software.

Key takeaways

The Open Source Definition belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect The Open Source Definition to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of The Open Source Definition from memory before moving on to harder problems.

Reference excerpt

The Open Source Definition (OSD) is a policy document published by the Open Source Initiative in 1998. Derived from the Debian Free Software Guidelines written by Bruce Perens, the OSD is the predominant standard for open-source software. The definition has ten criteria, such as requiring freely accessed source code and granting the open-source rights to everyone who receives a copy of the program. Covering both copyleft and permissive licenses, it is effectively identical to the definition of free software, but motivated by more pragmatic and business-friendly considerations. The Open Source Initiative's board votes on proposals of licenses to certify that they are compliant with the definition, and maintains a list of compliant licenses on its website. The definition has been adapted into the Open Knowledge Foundation's Open Definition for open knowledge and into open hardware definitions.

History There have been several attempts to define open source and free software. Amongst the earliest was Free Software Foundation's Free Software Definition, which then defined as the Three Freedoms of Free Software (Freedom Zero was added later). Published versions of FSF's Free Software Definition existed as early as 1986, having been published in the first edition of the (now defunct) GNU's Bulletin.

Debian Free Software Guidelines The Debian Free Software Guidelines (DFSG) was first published together with the first version of the Debian Social Contract in July 1997. The primary author was Bruce Perens, with input from the Debian developers during a month-long discussion on a private mailing list, as part of the larger Debian Social Contract. Perens was copied to an email discussion between Ean Schuessler (then of Debian) and Donnie Barnes of Red Hat, in which Schuessler accused Red Hat of never elucidating its social contract with the Linux community. Perens realized that Debian did not have any formal social contract either, and immediately started creating one. The (then) Three Freedoms, which preceded the drafting and promulgation of the DFSG, were unknown to its authors. The guidelines were:

Free redistribution. Inclusion of source code. Allowing for modifications and derived works. Integrity of the author's source code (as a compromise). No discrimination against persons or groups. No discrimination against fields of endeavor, like commercial use. The license needs to apply to all to whom the program is redistributed. License must not be specific to a product. License must not restrict other software. Example licenses: The GNU GPL, BSD, and Artistic licenses are examples of licenses considered free.

Open source As Netscape released the open-source Mozilla browser in 1998, Bruce Perens again drafted a set of open-source guidelines to go with the release. It has been claimed that the Open Source Definition was created by re-titling the exact text of the DFSG. A modified version of this definition was adopted by the Open Source Initiative (OSI) as the Open Source Definition. The OSI uses the label "open source", rather than "free software", because it felt that the latter term had undesirable ideological and political freight, and it wanted to focus on the pragmatic and business-friendly arguments for open-source software. It adopted a closed rather than membership-driven organizational model in order to draft the definition and work together with a wider variety of stakeholders than other free or open-source projects. Once the DFSG became the Open Source Definition, Richard Stallman saw the need to differentiate free software from open source and promoted the Free Software Definition.

Debian diverges In November 1998, Ian Jackson and others proposed several changes in a draft versioned 1.4, but the changes were never made official. Jackson stated that the problems were "loose wording" and the patch clause. The Debian General Resolution 2004-003, titled "Editorial amendments to the social contract", modified the Social Contract. The proposer Andrew Suffield stated:

"The rule is 'this resolution only changes the letter of the law, not the spirit'. Mostly it changes the wording of the social contract to better reflect what it is supposed to mean, and this is mostly in light of issues that were not considered when it was originally written." However, the change of the sentence "We promise to keep the Debian GNU/Linux Distribution entirely free software" into "We promise that the Debian system and all its components will be free" resulted in the release manager, Anthony Towns, making a practical change:

"As [SC #1] is no longer limited to 'software', and as this decision was made by developers after and during discussion of how we should consider non-software content such as documentation and firmware, I don't believe I can justify the policy decisions to exempt documentation, firmware, or content any longer, as the Social Contract has been amended to cover all these areas." This prompted another General Resolution, 2004–004, in which the developers voted overwhelmingly against immediate action, and decided to postpone those changes until the next release (whose development started a year later, in June 2005).

Criteria Providing access to the source code is not enough for software to be considered "open-source". The Open Source Definition requires that ten criteria be met:

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with The Open Source Definition

Start with the simplest possible case. Write down what The Open Source Definition claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to The Open Source Definition before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about The Open Source Definition ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of The Open Source Definition

In research: The Open Source Definition appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses The Open Source Definition in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: The Open Source Definition is common in secondary-school and first-year university syllabi. It links to neighbouring topics Definitions, Open source, so understanding it makes those chapters shorter.
In everyday life: Look for The Open Source Definition outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study The Open Source Definition in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what The Open Source Definition means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain The Open Source Definition out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is The Open Source Definition in simple terms?

Why does The Open Source Definition matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study The Open Source Definition?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on The Open Source Definition.