Say a user is called Beowulf. In a comment under his posting you try to start with "@Beowulf". I know I've seen this done. But several times, the software has edited that out when I hit "save". I have no idea how to tell when this will happen and when it won't. That the software can overrule my decisions about content seems bizarre, not to mention abusive. What's going on?
If you click the "help" link under the Add Comment button, it explains that the post owner is always notified, making
@postowner redundant, particularly in the case where your comment is the first one.
The post author will always be notified of your comment. To also notify a previous commenter, mention their user name: @peter or @PeterSmith will both work. Learn more…
Additionally, if you click the "learn more..." link in the abbreviated help it links to the complete help:
There is also autocompletion in the case where multiple people are in the comments, so if you type
@ and don't get a popup for completion, you know that the
@username is superfluous in that situation.