Login
A login is an assumed individual identity, consisting of a string that refers to either a pseudonym used by no body or a real name used by some body, often without any clue as to which.
A single login has been proposed and is being added to MediaWiki to support the sysop power structure in their attempts to assign alleged and collective identity to others, those who they typically label "trolls". A side effect of this outing effort might be some useful functionality. But don't count on it.
These are the same people who promote libel addicts as Wikimedia Treasurer, and justify sysop vandalism almost as a pathological habit.