Now I’ve observed that in a lot of older questions those usernames that were referred to where nowhere to be found in that question. This has of course to do with the fact that users can change their username. And if questions are older it is not unlikely that a user which has been referred to in an answer or comment has changed his username in the meantime. Often you can figure out who was meant if for example there are only two answers or by examining the time stamps of answers etc. But other times you can’t.

This is where username tags come in. Analogously to the chat, wouldn’t it be possible to implement tagging a user via @[username] in comments and answers and let the system display it as the plain text username? One could implement it so that when the tag is made it is linked to the unique user ID which is associated to the [username] at the time of the tagging and therefore the tag is independent of a change of the user name. To prevent tagging from escalating, one could limit the usernames which are allowed to be tagged to the current question i.e. to only the users which have participated in the question by writing an answer or a comment.

I’m aware that the tagging is already possible in comments, but I believe it doesn’t adapt if the user name changes and after all it is not possible yet in answers.

• Some past post about comment-replies and changed username: on this meta: To whom am I replying? Feature request on Meta Stack Exchange marked (status-declined): Change all @username references in comments when a user changes their name? Apr 28, 2018 at 2:44
• Based on general SE philosophy, I think it's arguable that comments needing this functionality are using the comment system incorrectly.
– user14972
Apr 28, 2018 at 3:54
• Thanks @MartinSleziak. I wasn't aware that the issue has already been discussed in SE Meta. Although sad, the reasons they mention for not implementing a feature like this are understandable. Apr 28, 2018 at 13:47
• The @ syntax is intended for notification of a user, so it has somewhat limited temporal utility. Over a longer period of time, it might be that one wishes to identify a Math.SE user by linking to their profile, ie. using the standard [ ]( ) mechanism. For example one might wish to identify the author of a book or paper mentioned by OP as being a frequent contributor here (rather than trying to ping such a user). Apr 28, 2018 at 17:49
• I wrote down my thoughts on using @username in questions/answers in my answer to this question on Meta MathOveflow: Is it good practice to write “@someone” in a question? (BTW does somebody remember whether there was a discussion about this topic also on this meta?) Apr 29, 2018 at 11:54
• Jan 12, 2020 at 20:48