Both copyleft and share-alike have the same characteristics. Share-alike is obviously also the name of a CC license component.

Reading the tag wiki, it seems they refer to the same thing.

  • Should they be synonyms?
  • If so, should there by any other tags rolled in to it?
  • What should be the 'primary' name?
  • If not, how can we improve the tag wiki to differentiate between them?
  • 1
    This is status-completed :D It was a simple merge, all questions that had share-alike already had the copyleft tag anyway.
    – Zizouz212
    Commented Sep 1, 2015 at 23:48
  • 1
    Hm... given that the GPL, one of the most prominent copyleft licenses, and CC-BY-SA, which has share-alike in its name, are incompatible, I find this to be an unfortunate merge. Commented Sep 19, 2015 at 11:20
  • 2
    @MichaelSchumacher can you give an example of a question (hypothetical or not) where it would matter?
    – Martijn
    Commented Sep 19, 2015 at 14:21

2 Answers 2

  • Yes. The concept behind them is exactly the same. We already have for one of the licenses, we don't need a tag just for the clause.
  • I haven't seen any, but I'm willing to add more in if they're suggested :)
  • Probably . It's a broader tag, and encompasses . If they're this way round, we can simply merge the two, and will still apply to the questions.
  • N/A. I think the two should be synonymized.

(N.B. With a few more votes, if nobody objects, I'll merge the tags.)


They aren't exactly the same terms, share-alike is broader. Copyleft includes the content to be free, while share-alike only demands sharing under the same terms, even if the term itself are non-free. best example are the two share-alike cc-licences. cc-by-sa is copyleft while cc-by-nc-sa is non-free and therefore not copyleft.

https://en.wikipedia.org/wiki/Share-alike vs. https://en.wikipedia.org/wiki/Copyleft

How does this impact the tags? I don't know really. If Ziz says all uses of share-alike already had copyleft too, then share-alike is unneeded.

  • 2
    Copyleft isn't narrowly defined, so two people could differ in their opinion of whether cc nc-sa is copyleft or not (though not if it is free or not: it's not). This does make a reasonable case for having the synonym reversed though
    – Martijn
    Commented Sep 2, 2015 at 12:29
  • 1
    @Martijn Ah heck, we can just update the tag wiki excerpt for that. :)
    – Zizouz212
    Commented Sep 2, 2015 at 20:05

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