As was noted in comments below the question Is the longitude assigned to sunspots spherical or projected? it is impossible to create a tag.

Trying to do so results in the error message:

The tag [sunspots] is too similar to [sunspots]. If you think this new tag should be allowed, discuss it on meta.

I wonder if the tag existed once? It seems to be on some kind of "no-fly" list now.

  1. Why does this happen exactly?
  2. Should we have a tag?

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  • 1
    $\begingroup$ I wonder if the tag was blacklisted in order to favor another tag that never got created, like the newly added solar-activity. If so, I have no memory of it. A member of SE staff made sunspot a synonym of the blacklisted sunspots. $\endgroup$
    – called2voyage Mod
    Commented Jun 20, 2019 at 18:32
  • 1
    $\begingroup$ I made a suggested [solar-activity] tag in the meantime as it could be more generally applicable. Could also have a [stellar-activity] for magnetic-related phenomena (spots, flares etc) on other stars $\endgroup$ Commented Jun 20, 2019 at 18:33
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    $\begingroup$ Some feedback from the CM team suggests this is actually a bug, not a blacklisting. $\endgroup$
    – called2voyage Mod
    Commented Jun 20, 2019 at 19:44

1 Answer 1


I've recreated the tag but if you want to keep it around for more than six months, find another question to add it to or give it a tag wiki. Or, if you decide that you don't want it, just remove it from the question and it will go away in 24 hours.

This hinges on a prohibition in tag creation coupled with a synonym where the master is deleted.

Long ago we made it so that the singular and plural versions of a tag could not be user-created - because usually that'd be confusing to have both except in rare situations. In many cases, if the singular tag is created first and someone wants to have the plural instead, it's possible, it just requires a mod to intervene to "force" the tag... and by "force" I mean to create it because they're exempt from the plural check. The other option (which is available to all users) is to remove the tag from all posts, wait 24 hours for it to be deleted, and then create the plural tag.

In this case, hairboat was super helpful by not only creating the sunspots tag, but also synonymizing sunspot to it to prevent both being used separately... unfortunately, in your case, the tag only got used on one post and was deleted.

The chain of events, as far as I can see is:

  1. The "sunspot" tag is created.
  2. Someone realized that it should be plural ("sunspots") and asked for help to pluralize it.
  3. hairboat created a synonym on September 24th 2013.
  4. The tag only appears on a single question so after (about) six months, the system deletes the tag (April 19, 2014).
  5. An attempt to recreate the tag (today) fails because the synonym exists but is pointing to a non-existent tag plus users can't create tags that are too similar to other tags.

Some notes:

  • If a moderator had tried to create the tag, they should have been able to just fine because they're exempt from the "too similar" rules just as I am.
  • The tag is not blacklisted and never was.

This is a suuuuuuper rare thing, I'm guessing... it's probably pretty uncommon for a tag with a synonym that's only one character off (plural) to get deleted and then tries to get recreated. Without the tag synonym, nothing would have stood in the way of creating this tag.

So, while we could probably poke at this and figure out how to handle this more gracefully, I'm not sure how pressing it is. Also, since mods can already override the tag creation, there's sorta already a solution.

  • $\begingroup$ The first bullet in the notes is wrong. I tried creating the tag and it would not let me. $\endgroup$
    – called2voyage Mod
    Commented Jun 20, 2019 at 20:33
  • $\begingroup$ And I don't think the general situation of having single use tags get synonymized like this is rare. We have a number of them on Space Exploration. Because the community over there is more proactive about tag wikis, those didn't fall prey to this problem, but in communities like Astronomy where tag wikis are created less often I could see it being a problem. $\endgroup$
    – called2voyage Mod
    Commented Jun 20, 2019 at 20:38
  • $\begingroup$ @called2voyage There's 5 single-use tags with synonyms on SE.SE and none of them are one-letter-off tags. $\endgroup$
    – Catija
    Commented Jun 20, 2019 at 20:48
  • $\begingroup$ That's why I said general synonym situation--but maybe I overstated the case. $\endgroup$
    – called2voyage Mod
    Commented Jun 20, 2019 at 20:49
  • $\begingroup$ My guess is that the single-letter-off thing is what's really causing the problem. So, if you had biscuits -> cookies and cookies was removed, you'd be able to recreate cookies just fine... but I could be wrong. If I'm correct, though, I think it's pretty rare. That said, I'm not sure why you couldn't add the tag... you should have been able to. $\endgroup$
    – Catija
    Commented Jun 20, 2019 at 20:53
  • $\begingroup$ Fair enough. Any insight into why I couldn't create the tag? $\endgroup$
    – called2voyage Mod
    Commented Jun 20, 2019 at 20:54
  • $\begingroup$ Just saw your edit--well, I guess that's a mystery unless this issue comes up again. $\endgroup$
    – called2voyage Mod
    Commented Jun 20, 2019 at 20:54
  • $\begingroup$ Probably worth noting in the answer though $\endgroup$
    – called2voyage Mod
    Commented Jun 20, 2019 at 20:55
  • $\begingroup$ Can you try to add "coordinates"? I see that "coordinate" is a tag but I'm guessing "coordinates" may be better? Alternatively, any other singular-> plural change (stars, planets)? ... what is y'all's policy on plural tags? $\endgroup$
    – Catija
    Commented Jun 20, 2019 at 20:56
  • $\begingroup$ We haven't made a policy, but I think we prefer plural. $\endgroup$
    – called2voyage Mod
    Commented Jun 20, 2019 at 21:01
  • $\begingroup$ That's what most sites opt for, if they pick. I notice y'all have a bit of a mix so this might be a good chance to think about it. :D Because everyone loves tag discussions!!! (just kidding... sadly, most people find them annoying). Anyway, I'm a fan of plurals so if you want to test it, let me know whether you have issues with that. $\endgroup$
    – Catija
    Commented Jun 20, 2019 at 21:03
  • $\begingroup$ It let me create the plural form, but I'm not sure this is a good test case, because in the case of sunspots the plural already existed but had aged away. $\endgroup$
    – called2voyage Mod
    Commented Jun 20, 2019 at 21:05
  • $\begingroup$ I mean, you can test that, too... create a plural form, remove it, wait 24 hours for the tag to get deleted, try to create it again. If anything, I'm guessing it's the synonym that caused the problem but it's all pretty simple to test if you're patient. :D $\endgroup$
    – Catija
    Commented Jun 20, 2019 at 21:07
  • $\begingroup$ True, I guess I'll go ahead and test that. $\endgroup$
    – called2voyage Mod
    Commented Jun 20, 2019 at 21:07
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    $\begingroup$ @called2voyage Huh. Taking a look through the code, I have no idea what happened here. Could dig more, but as Catija said, this is a rare occurrence. Please let us know if you hit something similar again, but for now I think we can let it be... and maybe blame some sort of a celestial body for being in retrograde. Or sunspots. :) $\endgroup$
    – Adam Lear StaffMod
    Commented Jun 20, 2019 at 21:31

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