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This page presented an issue for consideration in the CC license suite 4.0 versioning process. The discussions have now concluded with the publication of the 4.0 licenses, and the information on this page is now kept as an archive of previous discussions. The primary forum for issues relating to the 4.0 versioning process was the CC license discuss email list. You may subscribe to contribute to any continuing post-launch discussions, such as those surrounding compatibility and license translation. The wiki has been populated with links to relevant email threads from the mailing list where applicable, and other topics for discussion were raised in the 4.0/Sandbox. See the 4.0 page for more about the process.


Page summary: Creative Commons changed the definition of "compatible license" to allow for more possibilities, including one-way compatibility. A discussion about criteria and processes for determining other compatible licenses will happen after the launch of 4.0. Additionally, a compatibility mechanism was added to BY-NC-SA. Compatibility was first introduced in version 3.0, although no licenses have yet been declared compatible.

Treatment in drafts

(expand to read Draft 1 treatment)

Draft 1

Not directly addressed in draft 1.

(expand to read Draft 2 treatment)

Draft 2

Discussions are underway but have not progressed to the point where specific CC provisions have been adjusted. Both FAL and GPL have been extensively reviewed, however. Where small points of convergence are easily made without substantive changes, those have been incorporated in our drafting.

(expand to read Draft 3 treatment)

Draft 3

In this draft, the definition of “Creative Commons Compatible License” has been revised to remove the minimum criteria for what is “essentially the same as this Public License”. This change leaves the essential part of the definition within the text, but provides an opportunity for CC to engage in a longer discussion with the community about some possible changes while not holding up the versioning process. Please take note that this removal should not be taken as a sign that CC has made up its mind as to the outcome, or is even leaning in some particular direction -- it is merely building in flexibility to have a longer discussion before any decision (let alone any change) is made. Our goal has been to design a mechanism that can be used if such a decision is made after further discussion, thereby avoid the need for versioning once again.

Additionally, the compatibility mechanism has now been included in the BY-NC-SA license as well as BY-SA. This is not expected to have much practical effect: CC is not currently aware of any license that would be a candidate for compatibility, nor do we expect one to be written. The possible downside is that including such a mechanism may indirectly encourage others to develop such a license, in the knowledge that it would be possible to become compatible in the future. However, in light of our goal for 4.0 of greater interoperability, we believe that on balance including this mechanism is the right decision even if it goes unused.

For the d3 discussion period in particular, we will first be seeking input on the revision to the Creative Commons Compatible License definition to enable one-way compatibility from BY-SA to other similarly-spirited ShareAlike licenses. The previous definition foreclosed this possibility entirely, requiring that any license recognized as compatible must be two-way compatible. In the current draft, one-way compatibility is not explicitly enabled, but the possibility is not closed off. This issue requires more community discussion to determine whether the license community believes that enabling one-way compatibility respects the expectations of the SA license, and if so, how best to enable it.

Second, we will seek feedback on the inclusion of the compatibility mechanism in BY-NC-SA. Note that issues relating to compatibility for BY and BY-NC are raised on the Treatment of Adaptations page.

Finally, we will be developing in collaboration with our community a more complete set of criteria for determining compatibility (two-way and, if a decision is made to pursue one-way, then that as well). Those criteria would live outside the license text on established pages. This will also involve development of a process for determining compatibility and, ultimately, a list of compatible licenses.

Draft 4

After a period of consultation, we have decided to go forward with the changes proposed earlier: we will keep the revised definition of a compatible license, and will be including the compatibility mechanism in BY-NC-SA.

We are also changing the defined term for compatible licenses. Instead of "Creative Commons Compatible License,” we will use "BY-SA Compatible License" and "BY-NC-SA Compatible License" to refer to licenses that are compatible with BY-SA and BY-NC-SA respectively. This change will help differentiate the sets of licenses that are compatible with BY-SA and BY-NC-SA, and will help make it clear that the terms only refer to licenses that are compatible with the ShareAlike licenses.


How CC thinks about compatibility generally

In general, a license may be compatible with one of the CC licenses when it is possible to comply with both sets of license terms simultaneously. When two licenses are compatible, you may take a work licensed under the first license, remix it and thereby create an adaptation, and apply the compatible license to your remix. The ShareAlike licenses are a special case: because of the copyleft mechanism, only licenses that CC has explicitly named may be compatible. For the BY and BY-NC licenses, compatibility is less constrained, and more complex. More detail and explanation about compatibility for the non-ShareAlike licenses is on the Treatment of Adaptations page.

Explaining compatibility with ShareAlike first requires knowing how adaptations work in general. By definition, an adaptation is a new work based on the pre-existing work and new contributions by the person creating the adaptation. The rights of the adapting remixer does not extend to the pre-existing material.[1] This is a complexity of copyright law, not the CC licenses themselves. In the CC licenses, when an adaptation of a CC-licensed work is created and licensed, the new license only applies to the adapter’s new contributions and not the original content. The original work is licensed to the downstream user directly from the original author. A user of an adaptation licensed under a CC license is receiving and must comply with (at least) two licenses -- one from the creator of the original work, and a second from the adapter (the person creating and licensing the adaptation) for use of the new content and modifications contributed by the adapter.

When you make an adaptation of a ShareAlike work, you must make that adaptation available under a compatible license. For ShareAlike, compatibility is allowed through the definition within the license as well as the section on sharing Adaptations. However, CC has not yet named any other licenses as compatible with ShareAlike. This page explores the mechanism and process for doing so, as well as potential candidates for compatibility.

Potential compatible licenses


In CC's view, FAL 1.3 is a strong candidate for two-way compatibility with BY-SA 4.0. Discussions are currently underway that we hope will allow remixing between two similarly-spirited but currently separate islands of content. We are working through details of what adjustments may need to be made in order to accomplish this goal. We will be vetting those fully with our communities between now and d3. It is possible that some tweaks may needed to be made to our licenses to make that happen, affecting current drafting. In terms of operationalizing such a statement on the CC side either through a reference in the license itself or inclusion on our existing (empty) webpage [link], this is an open question that will be addressed once more progress is made. For now, d2 contains the same compatibility language as 3.0 and maintains the definition of Creative Commons Compatible License and structure.


CC is also looking at one-way compatibility from BY and BY-SA to the GNU GPL v3.0. While the benefits may not seem immediately apparent to some given that CC is suitable for content and not software, the reality is that increasingly, people are creating works that mix content and code in ways that create uncertainty around how the licenses interact. As software becomes a greater part of artistic creation in the future, we want to be sure that people who want to release these works freely can do so without worrying about potential compatibility problems.

There are a few examples. One is 3D printing, where a creator of a functional design licensed under the GNU GPL may want to incorporate designs and art released under BY-SA. Many designs people are currently creating and remixing are being treated like software--mostly functional, with creativity tying its elements together--and licensed under a software license. But the more people are able to do with these works, the more benefit there will be in making another body of content legally accessible.

Another is interactive games and art, which generate new artistic works by using code to combine existing smaller works. Video games are code, but also art, and some blur the distinction so much that you can’t separate out the elements to treat them as a simple aggregation. Many generate new, original graphics or music based on the underlying code and the player’s actions; where they are built from BY or BY-SA licensed pieces, it may be necessary to ensure that they are compatible.

  • GPL Compatibility. CC BY does not make any specific requirements on the exact license an adaptation may be released under, but it ought be possible for a downstream licensee of an adaptation to fulfill CC BY conditions when fulfilling conditions of license adaptation offered under, ie conditions of license adaption under should be a superset of CC BY conditions. CC BY may be slightly misaligned with GPL such that latter's conditions not a strict superset of former. FSF says CC BY is not GPL compatible -- https://www.gnu.org/licenses/license-list.html#ccby

Considerations regarding compatibility of other licenses (community commentary on the subject)

  • Consider addressing uncertainty regarding releasing a work (adaptation/ derivative) under a CC Compatible license
    • When I thought about CC-BY-SA 3.0 --> GFDL transition as a hypothetical case, it was not necessarily all clear how I would "follow" GFDL after creating a derivative of a CC-BY-SA'd work.
    • To address the uncertainty, consider developing a "exemplary practice guideline" that would serve as a "safe harber" - i.e. the range of practice that is considered to be "in compliance" with both licenses for the transition purposes. Practice outside of the guideline may be okay, or maybe not. Insert some language to make this safe harbor effective in 4.0. After some licenses become compatible, develop such guidelines with steward of the compatible license.

Please add other important considerations to this discussion here.

Proposals relating to compatibility in 4.0

For ease of reference on discussion lists, please do not alter proposal numbers.

Compatibility Proposal No. 1: Clarify definition of Creative Commons Compatible License. (Currently, "Creative Commons Compatible License" means a license that is listed at http://creativecommons.org/compatiblelicenses that has been approved by Creative Commons as being essentially equivalent to this License, including, at a minimum, because that license: (i) contains terms that have the same purpose, meaning and effect as the License Elements of this License; and, (ii) explicitly permits the relicensing of adaptations of works made available under that license under this License or a Creative Commons jurisdiction license with the same License Elements as this License."

  • Pros:
  • Cons: Current language is ambiguous. Does it mean (a) the compatible license must give options for a licensee to pick any of those CC licenses? Or does it mean that (b) the compatible license must give at least one of those CC licenses as an option?
  • Other comments: Better wording (though I am not a native speaker) suggestions, for (a) and (b) above, respectively, are:
      • (ii) explicitly permits the relicensing of adaptations of works made available under that license under any of the Creative Commons licenses with the same License Elements as this License, including this License.
      • (ii) explicitly permits the relicensing of adaptations of works made available under that license under at least one of the Creative Commons licenses with the same License Elements as this License, such as this License, Creative Commons Attribution Share-Alike 3.0 Australia license, or Creative Commons Attribution Share-Alike 2.0 Japan license.
  • Treatment in 4.0 d.1: Not addressed in this initial draft; only BY-NC-SA is published for review during this first comment period. Please continue to put forth and comment on proposals for draft #2, which will likely include all six licenses.
  • Treatment in 4.0 d.2: Not addressed.
  • Treatment in 4.0 d.3: Definition changed as explained in the summary at the top of the page.
  • Treatment in 4.0 d.4: Definition changed as explained in the summary at the top of the page.

Related debate

We encourage you to sign up for the license discussion mailing list, where we will be debating this and other 4.0 proposals. HQ will provide links to related email threads from the license discussion mailing list here.

Relevant references

Please add citations that ought inform this 4.0 issue below.


  1. Article 2(3) of the Berne Convention: “Translations, adaptations, arrangements of music and other alterations of a literary or artistic work shall be protected as original works without prejudice to the copyright in the original work.” (emphasis added)