@AloizioMacedo (1) I proposed a tag-wiki entry for a grad-curl-div tag, and this was meant to include some generalizations of the gradient, e.g., to functional analysis, but this could certainly be narrowed. (In fact my original intended scope for gradient was just the vector calculus gradient and its generalization to Riemannian geometry, but some other users' comments convinced me to broaden it.)

@AloizioMacedo (3) Yes, in practice these three operators are usually discussed together, but moreover---and unlike, e.g., determinant-trace-rank---they are a canonical trio (at least in dimension 3, which is the setting where one usually first does vector calculus); see my earlier comment supporting the particular order grad-curl-div of the operator names in the proposed tag for a short explanation of this.

(The trace and determinant are part of a canonical family: One could analogously subsume the trace and determinant in a hypothetical symmetric-functions-of-eigenvalues-tag, but that change would make the tag unrecognizable to people first learning about those operators.)

I will just add that even if grad-curl-div is crated, a typical question about gradient will still have vector-analysis tag in addition to this tag.

Considering that some doubts have been raised (and that the answer has been edited a few times), I will ask this again:

Maybe the new question would end up with no feedback from the community, maybe it would get some attention.

It is true that it often happens tag related issue do not attention from the users of this site.

And I also understand that in some situations somebody has to make a decision (typically the mods) - if it's unlikely that some reasonable consensus will be achieved on meta.

As a side note: If compared with MathOverflow, on this site the tag-related issues are typically discussed on meta, on MO changes to tags are most often done without any previous discussion. (Of course, the way it's done on MO also has it's advantages. If things are discussed on meta first, that usually slows down any changes to tag system.)

@MartinSleziak deleted-tag The tag wilsons-theorem has been removed: math.stackexchange.com/posts/3462324/revisions

@MartinSleziak deleted-tag The tag circle-inversion has been removed: math.stackexchange.com/posts/3446824/revisions

It seems that this was the first occurrence of circle-inversion.

SEDE: data.stackexchange.com/math/query/927958/… data.stackexchange.com/math/query/883845/…

The queries which also shows editors who added/removed the tag: data.stackexchange.com/math/query/1105163/… data.stackexchange.com/math/query/1038474/…

new-tag A new tag polymath-project was created by Trevor.

The same user posted recently on meta: Informally, would anyone be interested in starting a Polymath Projects type site?

@Jack It is explicitly mentioned in the tag-info: "Consider a more specific tag instead: (real-analysis), (complex-analysis), (functional-analysis), (fourier-analysis), (measure-theory), (calculus-of-variations), etc. "

However, I am not sure whether complete removal would be useful/feasible.

Yes, there was something on meta. (Possibly even several discussions.) I can see that you find some post yourself.

If you look at the posts linked there you can see some other posts: Why is the tag (analysis) useful? and Should the (analysis) tag be deprecated?.

Here are the questions on meta which contain [tag:analysis]: math.meta.stackexchange.com/…

Conversation about (analysis) tag in this room from 2012: chat.stackexchange.com/rooms/3740/conversation/analysis-tag

I learned about that from here: Is there a way to search for a question (or an answer) that mentions a tag?

You can see that (analysis) has been occasionally mentioned in this room: chat.stackexchange.com/…

Asaf Karagila mentioned (analysis) as an example when he asked this question: Can we please have a “deprecated tag” feature? But I do not know whether he planned to do something further with that.

I guess this might be more-or-less all I can say about analysis. (Although it look like a terrible linkfest.)

@Jack Do you mean this: analysis?

It is the same in chat as in the posts.

You can use [tag:analysis] to get analysis and [meta-tag:suggested-edits] to get suggested-edits.

BTW you could have simply checked the source of my message to see that: chat.stackexchange.com/messages/52837526/history

That might be useful also when you see something else in chat and you are curious how it was typeset in that message: How to view/copy source of a message in chat?