BUR #50228 has been rejected.
create alias outside_border -> over_border
topic #18363 Outside Background Border chose outside border for when a character is in front of the border. at the time an issue was raised that this tag name is kind of weird because it covers pillarboxed and letterboxed which aren't border tags so it can't imply border, but imo the bigger problem is that it's called outside border when the "border" in danbooru normally means the colored edges of the image and not an actual perimeter
on booru most posts are white border like this
and if you look at this again
you'll realize now that you've been brainwashed by booru's tagging system that this is a white border, not a black border (yes i'm serious). but you can't deny that is also a black border. so this post gets tagged both white border AND black border. maybe there should be a tag for this like layered border or outlined border but i'm not making it. it's not worth it.
as a consequence of this system when you have a post with a heart in the background like this
if it's only 1 heart, then that is called a heart border, because it's a border that is heart-shaped. but if it was two hearts, then that's not the shape of the border anymore and it would be a heart background. i didn't make these rules. they were already there when i arrived.
if you aren't convinced, see the white border wiki where i put my descent into madness in the examples section
so anyway now that we know what a "border" is we can say that in most posts tagged outside border the character is not, in fact, seen outside the border, because the border is at the edges of the image and you can't see the character's body outside the image to tag what you see, but you can see that the border is in the background so imo it should be called background border instead
but if it was called background border people may use it for things in the background that have a border, so instead i suggest over border because that's more unambiguous