When we last updated you to clarify concerns and answer questions about our transition to version 4.0 of the CC BY-SA license we committed to posting updates to the UI and addressing unanswered questions. I am happy to announce that we have met these goals. As of now, UI and Data changes are live network-wide that include showing the relevant CC versions for all post revisions and comments on all sites, updating footers, API updates, and other related sites.

Before detailing the changes, I will first address some of the open questions that remain from our last update.

The previous update defined the license changing from CC BY-SA 3.0 to 4.0 on May 2, 2018. What happened on this date?

Prior to this date, the Terms of Service linked to CC BY-SA 3.0. On this date, the link changed to point to the 4.0 license. It was updated as part of a process that was not led by the Community Team and there was no public announcement at time due to an internal disconnect at the time of the release.

In that case, what about the change from CC BY-SA 2.5 to 3.0 that took place in April 2011? Shouldn’t that also affect a similar change?

We can now affirm that the same change in license that was posted on MSE to be effective as of April 8, 2011 (from version 2.5 to version 3.0) also could not have retroactively changed the license of content. The UI update laid out below will reflect this and will attribute each piece of content to the relevant license version.

Based on this, we will be adopting the following rules relating towards classifying the licenses attached to content published on the site:

  • Content contributed before 2011-04-08 (UTC) is distributed under the terms of CC BY-SA 2.5.
  • Content contributed from 2011-04-08 up to but not including 2018-05-02 (UTC) is distributed under the terms of CC BY-SA 3.0.
  • Content contributed on or after 2018-05-02 (UTC) is distributed under the terms of CC BY-SA 4.0.

How do edits work? Can edits change the license on content that was already posted on the site?

  • Every time that a piece of content is published, the work is published under the CC BY-SA version as defined above, based on the publish date.
  • Every time a piece of content on the site is edited by a user, the editor creates a new version of the previous version. The new version of that work is considered to be republished and therefore governed under the CC BY-SA version in effect as of the day on which the edit was made.
  • Each revision to a work creates a new version and is licensed separately. Thus current version of any piece of content (that appears on the site) is the most recent revision, and will have a license version based on the date on which that revision was published.
  • This applies regardless of the size, the magnitude, or the significance of the edit that was made (except for the cases outlined below which are exceptions to this rule).
  • New edits do not modify the license that is attached to an old revision of the same content. That old revision continues to be licensed under its original CC BY-SA version.

The UI changes as defined below will make it clear (through the timeline page) the license version that applies to every revision for each question, answer, and comment on all sites.

Are there any types of post edits that do not cause new licensed revisions or changes to the license on the post?

Yes, there are a few:

  • Title or Body Rollbacks: do not create new licensed versions, as they do not add any content to that which was already published. The license on the post changes to the license on the rollback target revision.
  • Tag applications to questions are considered to be meta-data and are not included in the content that is being licensed. Thus, tag-only edits or rollbacks do not effect any license changes or create new licensed versions
  • The following system-initiated post edits do not create new licensed versions:
    • Commonmark migration edits
    • URL Rewrites
    • http to https replacements
    • MSO link to MSE link replacements
    • Insert/remove duplicate link edits

What license is applied to posts that are labeled Community Wiki?

When attached to a post, the Community Wiki label changes the display of the post on the site, and changes the way in which reputation is assigned.

Revisions to CW posts are to be treated in the same way as any other content revisions on the site with respect to the applicable license: licensed using CC BY-SA based on the date that the revision is made (which will be identifiable through the post timeline).

How can users upgrade the license of content that they own on the site from 2.5 or 3.0 to 4.0?

We are thinking about how we might enable users to mass update and republish their questions and answers (across all sites on the network) to change the license version from 2.5 or 3.0 to 4.0. This will require more discovery work on our end so we don't yet have a time frame on if or when this might be available, or how it would work. This feature would not add the ability to republish a subset of content. It would be all or none.

What will be the process for future license updates? Can I agree in advance to any license upgrades that Stack Overflow might adopt in the future for new content?

We will try our best to announce future license updates on the network at least one month prior to their being adopted for new content. This will give time for the Community to react and give feedback on the change.

Any future license version updates will only affect new content (or new revisions published based on existing content) that is published after the new versions are adopted on the network. There will be no way for a user to agree in advance to automatically adopt future license changes to their existing content.

So what changes have been made?

  1. The timeline for every question and answer has been updated.
    1. The top of the timeline page (underneath the title of the post) lists the CC BY-SA version of the latest revision made to the post.
    2. A new column labeled “license” has been added to the timeline table.
    3. Each line in the timeline labeled as “history” where the action is “asked”, “answered”, or “edited” has the CC BY-SA version that is applied to the given revision. Example of license display on the Timeline (some rows removed from screenshot for
  2. The share post popover now includes a link to the license version applied to the post (decorated with an rel="license" attribute) Share popover including license link
  3. Comment versions:
    1. The tooltip on the comment date includes the license version applied to that comment on creation.
    2. If a comment had multiple revisions, the revision display that is available to moderators gives the license version that applied to each revision of the comment.
  4. Footer text, other references:
    1. All references to the license throughout the site (including on the TOS) have been changed to “CC BY-SA” (or the same in lower-case).
    2. Text requiring attribution is no longer written. This is implicit from the definition of the “BY” section of the license name.
    3. The network footer has been updated to no longer reference version 4.0 of the license, and will now link to the /help/licensing page.
    4. Other references to the license in other sections of the sites on the network have been updated in the same way.
    5. Area 51 footer has been updated accordingly.
    6. The create chat page has been updated accordingly.
    7. The Public Terms of Service has been updated to use the correct format of "CC BY-SA" (instead of incorrect representations like "CC-BY-SA"). Current license version number (4.0) is included in text of the ToS (and not just in the link). A sentence has been added to the licensing section making reference to this post to give more details on how licenses are applied to content.
  5. API models include a new field called content_license that will return the license associated with that record:
    1. Post
    2. Question
    3. Answer
    4. Revision
    5. Comment
    6. Question_Timeline (type=revision)
  6. Data Exports & SEDE
    1. SEDE footer has been updated.
    2. SEDE query details updated to show the license applicable to that query.
    3. The following tables available on data.stackexchange.com will include (in the next refresh) a ContentLicense field: Posts, PostHistory and Comments.

We’re happy to hear any feedback you might have and will try to answer any questions as best as we can. However, please understand that we’re unable to provide any answers to questions about licensing that could possibly be interpreted as us giving legal advice.

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    Finally, it looks like it's consistent and a clean solution. The disconnect around May 2, 2018 is a bit unfortunate because it means that the community basically stayed in the dark. With the upgrade option you are thinking about, I fear it will not fly especially if it's all or nothing because you would mess around with later edits potentially having a lower license version number and having multiple licenses for the same content. It's a mess and not worth the effort. It's also not clear to me what the big advantage would be really if some people changed the licenses of some of the content. – Trilarion May 12 at 11:57
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    Thank you for this. I'll probably still argue about the finer details, but this puts SE back in the black as far as licensing is concerned, I think. – E.P. May 12 at 12:21
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    «the link changed to point to the 4.0 license» — I'm not sure, does this change really have legal force? This is just a link invisible to most users. The TOS does not mention exact version of the license as plain text, and the footer contained a mention of 3.0 until 2019-09. – andreymal May 12 at 17:04
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    Good work, Yaakov, thanks! (See, we can be positive when it's warranted :P) – Asteroids With Wings May 12 at 17:27
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    IANAL, but this looks as if you handled a messy thing well. – Raphael May 13 at 6:51
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    The Terms of Service has been updated – Yaakov Ellis May 13 at 14:53
  • Person A posted an answer in 2017. Person B makes an edit in 2020. Under which license is the edited answer? And, who is granting the license for the edited answer? – Anonymous Coward May 14 at 8:17
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    @AnonymousCoward See derivative work. With CC they call it remixing or adaptation. Basically the license stays the same but the version number can be increased. That means that in your example, person A allowed all other persons in 2017 to use their work and create derivative works (that's what person B is doing) under the same or higher version of the license. Since person B uses a higher version in 2020 (ToS of SO), that's the version that will be used – Trilarion May 14 at 9:27
  • @Trilarion so you response to my two questions is: License of the whole edited answer is CC-BY-SA 4.0 . And license of whole edited answer is granted by Person B. Is my understanding of your response correct? – Anonymous Coward May 14 at 10:22
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    @AnonymousCoward Almost correct. The whole edited answer is a joint work of two persons, so the license for this joint work is (must be) granted by both persons and the first person gave its okay already in 2017(only saying version 3 or above) while the second person gives its okay now and further limiting the version (saying now only version 4 and above which doesn't contradict the first person's wishes). But nobody does actually keep anyone from taking the answer of person A from 2017 now, edit it and posting it outside of SO with version 3 of CC. That would be still possible. – Trilarion May 14 at 12:27
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    What if I don't want to have my post re-licensed? As far as I understand it, the old license says that you can't force me to apply a new license to my posts, so I could refuse it. But my post is still my post, even after someone edits it. It's assigned to my account etc., it's not considered that person's work. And sometimes even bots or the community user edit posts, they are surely not the owner of the entire post of which I did 99.9% of the work on. That's as if I "remixed" a piece of music by cutting out a second of silence in the middle, let YouTube publish it on the original artist's … – Fabian Röling May 15 at 16:57
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    … channel (somehow) and then claim it as my work when a license question comes up. That can't be how it works, right? – Fabian Röling May 15 at 16:57
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    @FabianRöling "It's assigned to my account etc." The first creator of a question/answer gets rep for votes on it and is prominently displayed, but I guess that the content itself is not really assigned to that account. If there was an edit then the content should legally be a joint authorship. Now not every edit might warrant a joint authorship, probably there must be a certain amount of change and it's unclear (at least to me) if the community user can have authorship, so I don't know about the corner cases really. You could ask that as new questions, here or on law.stackexchange.com – Trilarion May 18 at 9:53
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    @FabianRöling "What if I don't want to have my post re-licensed?" -- largely, tough luck. The CC BY-SA 3.0 license explicitly allows anyone (in §4.b) to (i) create an adaptation of your post and (ii) license it under 'a later version of this License', so long as the adaptation is clearly marked as such (cf. "Edited" next to the signature, carrying a link to the edit history, when this is the case.) Your post is still your work, and the timeline (in the new system) explicitly marks it as such under the old license, (cont.) – E.P. May 19 at 15:57
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    ... but you've already given permissions for edits to your post to be licensed under the new license. It's as if you took a piece of music which was licensed under a Creative Commons Attribution-ShareAlike 3.0 license, edited it by cutting out one second, and then this was posted in YouTube with attribution to the original author and clearly marked as an adaptation; in other words, it's perfectly legal. (So you may ask, what was the original problem? it's that the 3.0 license allows adaptations to be relicensed, in §4.b, but §4.a does not allow the original to be relicensed.) – E.P. May 19 at 16:08

23 Answers 23


Tag only edits trigger a license change.

Update: Tag-only edits no longer trigger license changes

enter image description here

Please ignore the rollback.

Is this a bug? Are tags part of the post content?

If tags edits force a license change then any mass tag editing will update the licenses of every post affected.

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    Tags should be meta data, not part of the post content itself. They should not trigger license changes. – George Stocker May 12 at 13:07
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    @GeorgeStocker Not sure if this is legally the right interpretation. The ToS only talk about subscriber content which includes all kind of feedback that users give and that is licensed under CC-4 now. So maybe even my votes are licensed. :) – Trilarion May 18 at 9:58

Update: tag edits and edit duplicate lists no longer trigger license changes

Just like tag edits, editing the duplicates list trigger a license change (or at least an indication):

enter image description here

As you can see in the entry below it, just closing it as a duplicate doesn't, so it's clearly a bug.

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First of all thank you for this great piece of work, which fulfils a long standing debt to the community. I'm glad SE finally takes this licensing issue seriously.

As others mentioned before I too doubt that a very minor change warrants a license upgrade.

Changing a comma into a period in a written sentence definitely is very minor, and thus most likely doesn't classify as an adaptation of the original work. And as such wouldn't warrant it being licensed under the latest version of the license. The solution here would be to add some sort of minimum threshold. We all know that that doesn't deter users from posting a question, so why would the response here be any different.

On the other hand, changing a comma into a period within a code segment could have major implications for said code. It could be something that fixes or breaks the code entirely and therefore could be seen as an adaptation of the original. Which would warrant a change in license.

As there is no perfect way to classify the impact of an edit, I'd side with Yaakov here, and say that any edit should count, as that is the most practical solution.

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    Thanks. Your analysis of the impossibility of automatically classifying the impact of the edit is also a factor here. – Yaakov Ellis May 12 at 12:00
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    @YaakovEllis What about edits by bots, e.g. the HTTPS link rewrite bot? I don't think they create an adaptation in the sense of the CC licenses. – amon May 12 at 12:58
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    @amon better post that as a separate answer for better visibility. – Luuklag May 12 at 13:00
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    @Luuklag Unfortunately I have yet to find a post that can serve as an example – my SEDE-fu is not strong enough. In any case, I feel that SE must think carefully about whether any edit merits a license upgrade. There's a large grey area, but there are some easy to detect things like bot edits, typo corrections, punctuation changes. Unnecessarily keeping the old license wouldn't be very good, but upgrading the license without the existence of an Adaptation would be a license violation… – amon May 13 at 10:51
  • @amon posted an example with the URL Rewrite bot in this answer – River May 18 at 19:02

I just wanted to give a pure, unadulterated THANK YOU for the incredible work on this.

I'm sure there are details and fine points to be picked over but as a community member I wanted to acknowledge this work that has been done & pushed live, as well as the announcement, the community engagement, etc. It's very appreciated.

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Thank you for this. I'm glad this happened.

I still have concerns about how edits are handled, though. I find it odd that any edit - even the most minor ones - can cause a change in the license. I'm not entirely convinced that someone can take a CC BY-SA 2.5 or 3.0 post, fix one spelling mistake, and then release that under CC BY-SA 4.0.

I'm now OK with edits triggering a license upgrade between versions of a CC BY-SA license. At least in CC BY-SA 3.0, An adaptation can be released under "a Creative Commons jurisdiction license with the same License Elements as this License". Personally, I think it may be a stretch to consider the most minor edits an adaptation or derivative work, but there are also technological limitations if you tried to consider significance of edits.

I do hope that you allow a bulk upgrade of the license. Now that the concerns around the licensing have been resolved, I'd like to be able to make all of my content 4.0 and make sure that it is labeled as such.

You can now see the license version number on the share popover

sample of share popover

I would also suggest including the license information outside of the timeline. I think it should be visible on questions and answers, but perhaps it would be ok in the hover text around the attribution would be a good place, similar to how it is in the tooltip for the comment date. Also consider CC REL in the HTML markup for the page - this does support multiple licenses on the page and may provide hints to search engines and browsers as well.

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    Thanks, @Yaakov. I'm not sure how obvious it is, but it's much easier than the timeline page. – Thomas Owens Jun 15 at 15:50

What about tag wikis and excerpts? They are also (usually) contributed by users, and can be revised. However, at present there are no generally-accessible timelines for tag wikis (e.g., https://meta.stackexchange.com/posts/168600/timeline) or excerpts (e.g., https://meta.stackexchange.com/posts/168601/timeline). (There might be one visible to moderators, perhaps.) (At least, not on /posts/<id>/timeline.)

(I had a bit about making the timeline accessible, but turns out, that was this year: Add a link to the timeline of a post)

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Quick question:

  1. The following tables available on [data.stackexchange.com][19] will include (in the next refresh) a ContentLicense field: Posts, PostHistory and Comments.

Will the new field be ContentLicense? Or will it be ContentLicenseId with a separate table for decoding? (The former feels rather un-SEDE-like, with the prevailing preference for the latter presumably doing lots for space efficiency.)

Seriously, though: huge props on this. The fact that this is the type of question sparked by the announcement is a big sign that you guys got it pretty much right. I still have quibbles on just why the 3.0-to-4.0 watershed is chosen in May '18 rather than September '19, but given that the rest is now in order there's really no point in those anymore.

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    The new field will be ContentLicense. And thanks for the props. This took an immense amount of work. – Yaakov Ellis May 12 at 12:07
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    Thanks for putting in said work. It shows. – E.P. May 12 at 12:09

What's the full status of SE's license to the content in the upcoming (and present and past) ToS?

As has been noted previously, some of the language in the ToS is unclear, and can be read as dual-licensing the post, with a global CC BY-SA license as well as a narrower SE-specific license to distribute (but (sometimes) not to allow others to redistribute) the content.

Can we ask you guys, as part of the current effort, to clarify that situation for both past content as well as (crucially) for what will come in the update to the licensing section of the ToS?

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  • 2
    Are you just reasking the question here from your other post? – Yaakov Ellis May 12 at 12:10
  • Yes, mostly -- but also extending it to the new ToS, which I think is more important than the historical concerns. – E.P. May 12 at 12:10
  • (if it helps, I'm happy to put my rep where my mouth is regarding bumping that old post ;-).) – E.P. May 12 at 12:11
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    I think it is better to update the old post (and bump it) with anything new considering these changes. Can't promise a satisfying answer (as it might be one of those annoying "sorry, but we can't give legal advise situations), but I can look into it. – Yaakov Ellis May 12 at 12:12
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    @YaakovEllis Just edited. I can understand that SE's counsel would be reluctant to allow any official statement regarding the interpretation of the language in the ToS. But I hope that you (read: SE's counsel) can see that it'd be very disquieting to have the company refuse to confirm or deny interpretational aspects as basic as the number of licenses that apply to subscriber-provided content. It's perfectly fine for there to be a dual license, but if that's the case then the details should be crystal clear. – E.P. May 12 at 12:18
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    It's pretty ridiculous that we're asked to enter a contract with SE, but that SE refuses to explain what that contract actually entails. – OrangeDog May 12 at 23:10

Prior to [May 2, 2018], the Terms of Service linked to CC BY-SA 3.0. On this date, the link changed to point to the 4.0 license. It was updated as part of a process that was not led by the Community team and there was no public announcement at time due to an internal disconnect at the time of the release.

I get it, an internal disconnect happened and the link got changed, and since it was in the Terms of Service, it took precedence over other notices on the site. This in turn impeded the Community Team from announcing the change in advance, and so when it was announced, it seemed abrupt.

However, I'd like some further elaboration in the section this text was contained in. Specifically, I'd like to see the following points addressed:

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    Sorry, but I can't get into more details regarding how and why this happened, other than to say that the change went under the radar internally for quite a while and that we announced it as soon as the change was brought to the attention of the Community team. We now have processes in place regarding ToS changes that should help to prevent this from happening in the future (though of course, no process is perfect, and mistakes do happen). – Yaakov Ellis May 12 at 9:00
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    As for your 'questions raised at the time of the relicensing', that particular one is answered on another post a few days later, perhaps duplicating those posts makes sense. – Tinkeringbell May 12 at 9:02
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    We noticed the same day the TOS changes were announced. I trust now though that SE's changes in regards to MSE will hopefully mean that our posts here have a higher chance of being seen and relayed to the relevant company staff. 😊 – curiousdannii May 12 at 9:03
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    @Tinkeringbell I think 22 is more than "a few", and much discussion was had there about how that post answers nothing. – OrangeDog May 12 at 14:49
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    @OrangeDog it answers the question 'were lawyers involved' (yes), and you might need to recalibrate your calculator. Question linked by Sonic is asked Sep 22 '19, answer I linked was written Sep 27 '19. I think that's 5 days, which is less than 6-8 so 'a few' seems very well applicable. – Tinkeringbell May 12 at 15:05
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    @Tinkeringbell I was counting from "at the time of re-licensing". The separate question posts were only made after the initial ones were ignored. It also doesn't answer that question. It states that lawyers are involved now, but not whether they were consulted before the ToS change. – OrangeDog May 12 at 15:14

Update: Rollbacks now revert the license version on the post to the version from the target rollback revision

You say a rollback can't introduce a license upgrade. But can rollbacks to an earlier revision downgrade the post (i.e. its currently visible content) to that older revision's license?

It's technically a new revision but it's the old revision's content with no new content added. (remark: I'd prefer that you can't downgrade the license in any way.)

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    All answers are equally bad. As a producer of content, if I submitted an answer at CC-BY-SA-3.0 and the contents have not effectively changed, it should remain at that version, shouldn't it? On the other hand, as a consumer, it would be quite bewildering to copy some code, then discover that the license has changed to an earlier version of the license when I revisit the link (though it should be possible to figure out what happened if you have enough time and don't panic). – tripleee May 12 at 9:40
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    Rollbacks simply shouldn't downgrade so that anti-editing trolls get the rug pulled under their feet and can't pretend to want to "preserve their license". There is zero common sense reason not to upgrade your content's license to 3.0 or 4.0, other than trying to play authority games. – Christian Rau May 12 at 9:43
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    On the other hand, unilaterally changing the license of content I posted without my involvement shouldn't be too easy either -- remember, that's how we ended up here in the first place. There are trolls on both sides, and we don't want to give either an advantage. – tripleee May 12 at 10:10
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    The CC licenses don't let you upgrade the license version without making non-trivial changes to the content. – curiousdannii May 12 at 10:25
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    The current license on the post is really the license on the revision that is currently the revision of record on the post. So if you rollback to an older version, and that older version is now what is displayed as the version of record on the post, the license that applies to that older version is now the one that applies to the post (ie: to the content of the post that is currently being displayed). Fix for this edge case is currently pending review (so if you test it right now, it will just use the LastEditDate to determine the license. – Yaakov Ellis May 12 at 11:55
  • @YaakovEllis But that current revision is technically a new revision, it has a new revision number and is treated like its own revision, even though it has an older revision's content. Is that not enough to make it count as a new revision on paper? – Christian Rau May 12 at 11:57
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    The current revision is a new revision as far as our meta-data on the post goes, tracking all of the things that happened in the post's history. But content-wise, it introduces nothing new. – Yaakov Ellis May 12 at 12:02
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    The version before it was rolled back still exists -- in the history. E.g. version 1 is old license, version 2 is new license, rollback to version 1 is old license again -- but version 2 still exists. – ChrisW May 12 at 13:19
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    Would you expect that a post that is vandalized, then has that edit rolled back (to remove the vandalism), would have its license changed? I think of a rollback as an undo of an edit, and since there needs to be tracking the revision number gets updated. – 1201ProgramAlarm May 12 at 21:17
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    We're going to be looking at this again to confirm this approach. Just wanted to update about that here. – Yaakov Ellis May 12 at 22:13
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    @ChristianRau The common sense reason for being in control of upgrading your license is that some future version might introduce a clause you don't like. – StackOverthrow May 13 at 17:50

Finally thank you. But there are still concerning questions:

  • Why was the ToS being updated without legal oversight and/or why did your legal counsel not know how licensing works? This answer states they were at least by then "involved and on-board".
  • Why was the initial feedback that retroactive re-licensing wouldn't work immediately ignored, then later dismissed? Despite the familiarity staff should have had from the MIT re-licensing plan.
  • How will you ensure the above never happens again?
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    These are good questions but at this point you're beating a dead horse. Let it go and be happy that SO is finally listening again and getting stuff fixed. – NathanOliver May 12 at 12:24
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    Did you ever made mistakes that you then promised would never happen again? And? – rene May 12 at 14:29
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    @rene yes... and in a professional context I was expected to answer questions similar to these. – OrangeDog May 12 at 14:48
  • I'm sure we all get asked these ridiculous questions. It is about the answer, the expectations of the asker and what happens in reality. – rene May 12 at 15:01
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    @NathanOliver There are no dead horses. There are companies losing revenue for things they did 30 years ago. – StackOverthrow May 13 at 17:52
  • I tried to address the circumstances of the earlier change above. As far as this not happening again, as I wrote above, we now have much better processes in place surrounding license changes (and related communications with the Community) and ToS changes, partly to ensure that this wont happen again. – Yaakov Ellis May 19 at 20:40


Update: Rollbacks now revert the license version on the post to the version from the target rollback revision

Roll-backs are meant to revert the license to the version that the rolled-back version was posted under. The language of the tool-tip suggests that a revision was created at 20:20, which corresponds with the most recent roll-back. In itself this isn't a revision of course.

In this case the tooltip should read: "CC License is based on the most recent post revision, which was made on May 12 at 11:55" (as that is the time of creation of Revision 2).

enter image description here

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How will post dissociation requests work, since different license versions have different requirements for removing attribution?

For a while now, Stack Exchange has been processing dissociation (attribution removal) requests on all posts, regardless of whether they were edited (i.e. republished as an adaptation). From the signals I've picked up, it appears that this was mostly done just because the license required it and not because SE wanted to do it.

That post was published after the license change to 4.0, and the 4.0 license requires that attribution removal requests be processed on all contributions, including verbatim reproductions. However, the 3.0 license only requires dissociation upon request on adaptations (i.e. posts that were edited), and the 2.5 license doesn't require dissociation upon request at all.

How will SE handle post dissociation requests now that the license under which posts were made is now tracked, since it's only done as a formality required by the license? Will dissociation requests now be refused in cases where SE is not required to perform it (all 2.5 posts, and unedited 3.0 posts)? Or will they continue to be handled otherwise?

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    There are no plans to change the way that we will handle disassociation requests, or to treat posts that are under older license versions differently than they have been up until now. – Yaakov Ellis May 12 at 8:51
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    If I understand the situation correctly, the current practice (barring the edge cases with single-post profiles you document on q/317512) is to remove it from every version, as dictated by the 4.0 guidelines, and this is compatible with (but not mandated by) the 3.0 and 2.5 versions? If so, then it all sounds in order to me. If not, then I don't get the issue here. – E.P. May 12 at 14:46
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    AFAIKT attribution removal is also required by GDPR, regardless of the license. – OrangeDog May 12 at 14:46
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    @E.P. Not raising an issue here. Simply asking if SE will handle dissociations differently because they only do it as a legal formality and older versions of the license don't require dissociation upon request in all cases. – Sonic the K-Day Hedgehog May 12 at 18:59

A bit pedantic, but the comment timestamp tooltip has a superfluous space between the timestamp and the comma. And 'License' probably shouldn't be capitalized since it's not at the start of the list.

enter image description here

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Update: URL Rewriter updates (and others outlined above) no longer cause new licensed versions or post license version updates

Edits from the URL Rewriter Bot should probably be ignored. For example, this post1.

Since this bot actually has a distinct username from the Community user, (which also handles things like anonymous edits) it should be easy to special-case. (Not sure if this was later changed, as other URL-edits seem to be done by the Community user.)

There are plenty of other examples of this happening.

1Although this post is even worse since the edit is reverted (but not using a rollback) by Community a few days later.

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  • Should it really be ignored? After all it changes the content and every adaptation must have a license attached, or not? – Trilarion May 18 at 10:50
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    @Trilarion such a change is unlikely to constitute an "adaption" – River May 18 at 19:01
  • This is a very special case you uncovered, due to very sad circumstances. Please see my MSO question about this case here: meta.stackoverflow.com/questions/367314/… – Luuklag May 18 at 19:05
  • @Luuklag all my examples are due to that, yes. But theoretically any URL rewrite could cause it (http -> https for example). – River May 18 at 19:09
  • @River I'm not a lawyer, so I don't know. Links are important parts of the posts and changing them kind of risks losing access to their content. A changed comma or space in a text seems innocent but changing a link is a bit like changing a whole word. Not sure if this is not an adaptation. – Trilarion May 19 at 6:44

The .relativetime (and .relativetime-clean) elements whose title attributes now show the date-based license do not get their text updated as time passes anymore.

We have elements like

<span title="2020-05-15 19:58:12Z , License: CC BY-SA 4.0" class="relativetime-clean">26 mins ago</span>

and JS of:

var date = prettyDate(spans[i].title);
function prettyDate(time) {
  if (time == null || time.length != 20) return;

The recently added License: part means that it's no longer 20 characters long, so for these elements, prettyDate doesn't return anything, and the text doesn't get updated.

Maybe change it to:

var date = prettyDate(spans[i].title.split(' , License:')[0]);

or something similar.

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Update: URL Rewriter updates (and others outlined above) no longer cause new licensed versions or post license version updates

Would have posted this as a comment, but I guess it warrants a full answer. IANAL, etc, disclaimer, disclaimer, but: to the best of my understanding, at least under United States copyright law, a "purely mechanical" modification of something (which pretty much by definition includes anything bot-driven, for example) does not create a new copyrightable work.

If I'm wrong about this, it is most likely a confusion with the "sweat of the brow" ruling from Feist Publications v. Rural Telephone Service, but it definitely seems like territory that warrants a consultation with the legal department if that hasn't already been addressed. If it has, great, but from several of the responses here it doesn't seem like the logic / opinion covering this is well publicized to the community?

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Devil's advocate:

I dislike the 2.5 version of the license, because stuff, and want to use an old post under the newer 4.0 license. What is stopping me from making a "malicious" edit to upgrade the license version?

Or should I not be stopped at all?

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  • 5
    Nothing's stopping you, not even the Creative Commons BY-SA 2.5 license. As long as what you've done constitutes creating a Derivative Work as defined in the license, you can use it under any CC-BY license that is version 2.5 or newer. – Mark May 12 at 20:15
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    A malicious edit will probably be rolled back. A legitimate edit will do what you are looking for. Nothing stopping that. – Yaakov Ellis May 12 at 20:18
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    YaakovEllis perhaps malicious was the wrong term then. But I mean an otherwise reasonable edit, most likely very minor, just for the sake of upgrading the license. Which brings us to the point @Mark raises, and what I covered in my previous answer. We count all deviations as derived work, due to implementation constraints, which might not be in accordance with the license terms. I don't see any way out of this though. – Luuklag May 12 at 20:38
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    Pointlessly minor edits are bad, regardless of the reason. I think meaningful/beneficial edits are probably fine, even if your real reason is to upgrade the license. – V2Blast May 13 at 4:23
  • @Luuklag perhaps the word you were looking for was 'benign' rather than 'malicious' i.e. an edit that does not make the post better or worse, but would still cause a relicense to occur – Robotnik May 20 at 6:13
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    @Robotnik, I don't think the word benign implicates the ill intent that malicious does. – Luuklag May 20 at 8:22

Just to clarify the attribution requirements:

When a post has been revised, who should be credited as the "author?"

  • Every time a piece of content on the site is edited, the editor creates a new version of the previous version. The new version of that work is considered to be republished and therefore governed under the CC BY-SA version in effect as of the day on which the edit was made.
  • Each revision to a work creates a new version and is licensed separately. Thus current version of any piece of content (that appears on the site) is the most recent revision, and will have a license version based on the date on which that revision was published.

If "the editor creates a new version of the previous version" and the new version is "republished," it seems to imply that the revised post should be attributed only to the most recent editor. But if so, the original poster wouldn't receive any attribution.

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You can now see the license version number on the share popover

sample of share popover

It would be great if there was a setting or permanently to show the current license in the post metadata row under the title.

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  • 1
    This is likely to be too much of a UI hassle for the devs to implement, for too small of a public. However, it's pretty reasonable to ask for this information to be added to the actual metadata (i.e. as meta tags in the html source) as suggested in this previous answer. If that's implemented, then pulling the information from that meta tag and into the rendered page is a reasonable task for a user-side script. (Alternatively, this could be fished by a userscript from the revisions page using the API, but that's going to be quite slow.) – E.P. May 19 at 16:12
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    Showing it on the text under the title will have to wait for some other UI work on the post UX. We are going to try to include it in create/edit date hover text (see answer above) – Yaakov Ellis May 19 at 20:58

Please, show info about the comment license version in the timeline.

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  • 11
    The timeline license column is only about the actual post in question. Comment CC version is in the tooltip for the comment. And license stuff for answers are in the individual answer timeline. – Yaakov Ellis May 13 at 8:15

As someone who isn't really too concerned about licensing (I certainly don't care what use anyone makes of any content I've posted), I'm having trouble understanding how this applies in practice to reuse of code examples.

The stackoverflow.blog post "good coders borrow..." states "If you do copy code examples, please remember to provide attribution..."

How does this work for someone who searches for help, finds a code example on Stack Overflow without having created an account, and copies it? How is such a person even aware that the content is licensed?

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  • 2
    It’s quite trivial: everything you find anywhere on the internet is copyrighted unless explicitly stated otherwise. – Emil Jeřábek May 21 at 11:55
  • @EmilJeřábek - I'm not convinced it's quite as simple as that. Copyright law varies from country to country Even though "a very small part of someone else’s work can require permission (and hence attribution in this case) if that part is an important or integral part and was the result of skill and time", it's not clear to me that a few lines of code posted in response to a StackOverflow question automatically falls into that category. – Joe May 21 at 17:11
  • Copying a nine-line function (rangeCheck) was enough to qualify as copyright infringement, according to a U.S. district court in Google v. Oracle America. Other countries might have different standards, as you said, and I'm not familiar with how Australian copyright law works -- however, I'd be careful and make sure to attribute even a few lines of code. – jkdev May 24 at 3:54

For the most part, I think this is good news. I'm glad SE has taken this problem seriously and appreciate the effort to enable multiple licences for answers posted at different times.

But it seems strange and somewhat troubling that the smallest edit (fixing a bit of grammar, removing a redundant word here or there) can effectively relicence content that was offered on the understanding that an earlier licence applied.

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    Any edit will create a new version of the post. That version has its own license based on the date on which it is published. Even if it is a minor edit, it is still a new version, and this can be done because the original license grants permission to republish. We are not changing this. Now that we have the possibility of multiple licenses, it just means that it is possible that a much older version of the post was published under an old license, and a new version is under a newer license. The license on the post itself just equals the license on the most recent version that was published. – Yaakov Ellis May 12 at 11:58
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    @YaakovEllis I understand that. It still concerns me, but perhaps it's the best that can be done right now. – mkt - Reinstate Monica May 12 at 12:26
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    @mkt-ReinstateMonica If you are worried about the legal validity of the approach, you probably could ask a separate question about it. Even though you won't get an answer because StackOverflow doesn't give legal advice, it would still be an interesting question, I think. – Trilarion May 18 at 10:54
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    @YaakovEllis "Even if it is a minor edit, it is still a new version," while that sentence is correct logic it should not be used as a red herring. A minor edit is a new version, but that is besides the point. Mkt's question about the issue whether a minor edit is an adaptation (which is different from a new version of a post on SE). While this is a gray area and the CC license is not clear about what size of edit would qualify as an adaptation I believe that any reasonable mind would say that minor edit is not an adaptation. – Sextus Empiricus Jun 10 at 15:54
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    .... an adaptation is: "when the modified work is based on the prior work but manifests sufficient new creativity to be copyrightable" creativecommons.org/faq/… – Sextus Empiricus Jun 10 at 16:07

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