So I have this Aviation.SE question about an XKCD comic. I included the image, as well as a proper link back to the XKCD site (a similar question does the same).

I've had a user attempt multiple times to quote the image itself. He finally contacted me in comments and said this

The quote markup makes clear that it’s not part of the user-generated content, which automatically gets licensed under CC BY-SA 3.0 on Stack Exchange sites (the comic cannot be licensed/used under this license).

I think the question, as-is, makes it abundantly clear it's not my content, but it's not clear which of us is right. I've never quoted any image that wasn't mine so this is a bit different of an argument for me.

  • You removed the blockquote tag, but this tag is central to the question, isn’t it? As I clarified in my answer, the part you quoted doesn’t say that the image should be quoted to licensing reasons, but for making clear that the license doesn’t apply (it doesn’t, whether you quote or not). So this discussion isn’t about licensing (nor about copyright, because it’s assumed that you are allowed to include the image to begin with).
    – unor
    Commented Apr 14, 2018 at 1:08
  • @unor The question isn't about blockquoting per se, tho.
    – Machavity
    Commented Apr 14, 2018 at 1:11
  • Can you clarify? My comment you quoted is about "quote markup" (referring to the blockquote element), and my edits to the Aviation question added this markup. -- There are other ways to mark something as quote than using blockquote (but not with markup on SE), and you were already using one other way in the Aviation question, but in this Meta discussion you said that you "never quoted any image", so this can’t refer to these other ways, right? (and the answer would be simple: yes, you have to quote in some way, otherwise you typically aren’t allowed to use the image to begin with).
    – unor
    Commented Apr 14, 2018 at 1:19

2 Answers 2


From Creative Commons Attribution-NonCommercial 2.5 Generic (CC BY-NC 2.5):

If supplied, you must provide the name of the creator and attribution parties, a copyright notice, a license notice, a disclaimer notice, and a link to the material.

From XKCD's licensing info:

That is, you don't need my permission to post these pictures on your website (and hotlinking with is fine); just include a link back to this page.

The original pages distributing xkcd comics do not include the name of the creator, so I guess you don't need to include that, but they do include a license notice with a link to the license page, so you must preserve that as requested, as well as describing the licensing terms to make it clear that it's not part of the standard Stack Exchange content licensing. So maybe something like this:

So this recent xkcd comic (distributed under the CC BY-NC 2.5 license) is all about autogyros.

Using block quoting might be nice, but if the attribution is clear it doesn't matter, it doesn't have any further legal significance.

  • Sounds good to me. I added a proper licensing link to it. It's a lot clearer than a quote block (which is hard to see anyways).
    – Machavity
    Commented Mar 30, 2018 at 18:26
  • This answer is only about the specific image linked as example by OP, but I understood this Meta discussion to be general (as suggested by the discussion’s title, and OP’s last sentence), no matter the license.
    – unor
    Commented Mar 30, 2018 at 19:36
  • 1
    @unor I'm not sure how to get a broader response. While it's specific, it does at least give some guidelines
    – Machavity
    Commented Mar 30, 2018 at 19:40
  • 1
    @unor My final sentence is my answer to that, I suppose: it's about having clear attribution in compliance with the license, and block quoting is only one way to do that.
    – Jeremy
    Commented Mar 30, 2018 at 19:41
  • @JeremyBanks: Ah right, I see. If the image isn’t licensed under a license, would your advice change? Or would you also say it’s sufficient to use something like "In this image from [xy]" + [embedded image without quote markup].
    – unor
    Commented Mar 30, 2018 at 19:56

(Disclosure: This user was me. Note that I didn’t say that quote markup must be used for licensing reasons, I said that quote markup makes clear that the image doesn’t fall under this license.)

There is no reason to give images special treatment over text.¹ If it’s not your content, but you’re allowed to include it, quote it.

Now, using the quote markup is not the only way to quote something. For inline quotes, using quotation marks is perfectly fine. And there might also be other ways to mark something as a quote (e.g., with a note). But there is no reason not to use quote markup for block quotes, and images are in most cases (like in OP’s example) included as blocks.

We have an easy way that works (just prepend a >), why use something else?

Boring details

Not a legal issue

To be clear, not to use quote markup is most likely not a legal issue for the author nor for Stack Exchange (as long as quoting the work is legally allowed, and the quote is marked in another sufficient way). But the quote markup helps people that want to make use of the content published on Stack Exchange sites:

  • It’s the most obvious way we have (thanks to the styling of the blockquote element).

  • It’s machine-readable (thanks to the use of markup instead of natural language).

What if the image is licensed?

Doesn’t change that it’s a good idea to quote markup:

  • If the image is licensed under an incompatible license, the use is only allowed thanks to quoting laws. The license doesn’t come into effect. Specifying the license can be useful, but quote markup should still be used.

  • If the image is licensed under a compatible license, and the use of the image isn’t covered by quoting laws, your use is covered by the license, and you might have to give attribution according to the license. Still, using quote markup helps people (for the reasons mentioned above).

Only if you edit the image (if allowed), quote markup must not be used. It’s no longer a quote, the image is now a derivative work (and attribution might be required).

¹ > … (Markdown) generates <blockquote>…</blockquote> (HTML). The blockquote element is for quoted content, not just for text: "The blockquote element represents content that is quoted from another source, […]".

  • 1
    Be that as it may, there's no point in getting into an edit war over it.
    – ale
    Commented Mar 30, 2018 at 19:24
  • @ale: That was no war. I suggested two edits (1, 2) that also fixed other things in the question, and after getting both rejected, I asked OP in the comments. This made clear that OP misunderstood my edits (not noticing that they were about adding the quote markup), and this resulted in this Meta discussion.
    – unor
    Commented Mar 30, 2018 at 19:25

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