What is a linked comment?

I have received a comment on my video and on top it said "linked comment." Does anyone know what this is?
I believe it simply means that you clicked on a link that linked directly to that comment. For example, if you click on the time stamp to any comment in any video, it will open a new tab and that comment will be at the top with the text 'linked comment'. I'm pretty sure that's what it is. So you likely clicked there from an email notification to that specific comment.[DOUBLEPOST=1447551024,1447550903][/DOUBLEPOST]You'll also notice that if you click the timestamps of different comments that different tabs will open up, tabs with different urls all with the comment you clicked at the top of the comment section with the text 'linked comment' alongside it.
Just yesterday I was trying to figure this out, too! When you get a notification that somebody commented on your video and you click the notification it puts that specific comment near the top with "linked comment" next to it so you know that that's the comment the notification was referring to. You can even see up in the video URL something that looks like this: &google_comment_id=z13xzpdq3njreqbskvzqz3rhbwmexyls