I posted a question and tagged it "infinite-sequences". A high-reputation editor added a more general tag: ca.analysis-and-odes. Now, in principle, having a more general tag is fine---but this tag is the wrong one. In particular, none of the topics mentioned under "tag info" have much to do with infinite sequences. I think that the right general tag is "real-analysis". However, I don't want to start an editing war with a high-rep user.
It's tempting to think that the only role of tags is for classification purposes. However, tags play another important role which is to increase a question's visibility to certain users. There is a balance between the two roles:
- Don't use an irrelevant tag just to attract specific users.
- Don't just use highly specialized tags with little or no following.
In this case, the question is hard to classify; ca.analysis-and-odes is not completely irrelevant and real-analysis seems fine too. They both have large following. Since the question is not close to the five tag limit, so why not have both?
I would like to answer this question in two parts:
For the general question what to do if you disagree with an edit to your post. First, it is possible to comment-notify editors of a post (despite them not being suggested in autocompletion), and thus you could ask them regarding the edit and perhaps you find common grounds. Yet, second, I think on MO it is by and large common understanding that the owner should have in most cases the last word regarding their posts, and thus in case of actual conflict you should feel free to revert.
For the particular matter. I think the tag perhaps appearing 'wrong' could be a misunderstanding of tagging-conventions of MO, which at the moment (due to software-upgrade) are still not that visibly explained as they used to be. As said by Emil Jeřábek it is strongly encouraged to use at least one top-level tag for each (mathematical) question. These are the tags with two-letter prefixes that correspond to the math subject categories of arXiv, so this list http://arxiv.org/archive/math The one used for retagging your question ca.analysis-and-odes seems the relatively most fitting to me (except one goes for the utmost general gm.general-mathematics). In particular, on MO this tag (ca) is more or less the catch all (real) analysis tag. Note for instance that classical-analysis is a synonym of it. In some sense real-analysis is more or less a subtag of ca. (One can be of the opinion this top-level system is not optimal, but it is current standard, and the retagging seems in line with it, while the original tagging was in fact not.)