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In the CC-BY 4.0 public license, section 3(a)(1)(B) says if you Share the Licensed Material (including in modified form) You must "indicate if You modified the Licensed Material and retain an indication of any previous modifications".

What does "retain an indication of any previous modifications" mean here?

Brian Lacy
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1 Answers1

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Let's say Acme Company release something under CC-BY. They put in a copyright line which looks something like

(c) 2022 Acme Company

I then modify that thing, and in accordance with the license indicate I modified it, maybe something like

(c) 2022 Acme Company
Modifications by Philip Kendall, 2023

If you then want to modify my version further you must not delete the notification of my modification; i.e. your version must contain something like

(c) 2022 Acme Company
Modifications by Philip Kendall, 2023
Modifications by Brian Lacy, 2023

and not just

(c) 2022 Acme Company
Modifications by Brian Lacy, 2023

Philip Kendall
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    As a rightsholder, is there any reason not to just put (c) Philip Kendall 2023? – MadHatter Feb 01 '23 at 21:34
  • @MadHatter CC-BY requires that one takes "reasonable steps" to indicate that changes were made from the original. Of course you don't necessarily have to do that on the copyright notice (one could always state that fact somewhere else), but this seems like an effective way. If I had just seen two "copyright" lines, then one is not necessarily a modification of the other; it could have been two authors contributing to the original, for example. – Brandin Feb 02 '23 at 05:41
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    I take that point, I just fear that CC will have the effect of creating a second type of copyright statement, the which is not recognised by any other free software licence, and which may confuse matters. I might go for Modifications (c) Philip Kendall, 2023; do you think that would satisfy? – MadHatter Feb 02 '23 at 07:25
  • I agree with @MadHatter. Many modifications may have an impact on copyright. The "best practices for attribution" page of CC serve as a guideline, even though it does not detail how multiple modifications should be dealt with. – Martin_in_AUT Feb 02 '23 at 14:04
  • It seems to me that the Adapted Material would be licensable on its own terms -- whether CC-BY or something else -- so assuming the Adapted Material is also licensed under CC-BY wouldn't it be more proper to include two separate attributions, one for the original and one for the Adapted work? – Brian Lacy Feb 03 '23 at 02:03
  • Of course the "modified" notice would need to be included for both attributions in that case, so its essentially moot -- what I'm really asking is, why you would need to include multiple "modified" notices on the original license attribution if the Adapted Material has its own license (regardless of what said license entails). – Brian Lacy Feb 03 '23 at 02:06
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    You are asking "why you would need to include multiple "modified" notices on the original license attribution if the Adapted Material has its own license" ? It is because Section 3.a.1 of the CC-BY license tells you so, and by using the material you have agreed to that license. By applying your changes and possibly creating new copyright, the rights of the original creators and modifiers of the work don't just magically disappear. They remain and need to be respected in line with the requirements of the license. – Martin_in_AUT Feb 03 '23 at 08:56
  • Understood. I do wish the question of multiple successive adaptations was addressed more explicitly, e.g. in the Best Practices, however. I think your interpretation entirely reasonable, but I'm surprised I haven't found any other resources describing this provision the way you have here. Most seem to assume that attribution and notice of modifications in general is sufficient. – Brian Lacy Feb 05 '23 at 05:07