Requested feature overview description.
Turn the Source field into a 5x5 grid, like a small Excel worksheet

Why would it be useful?
On some art sites, like Furraffinity, the post URL doesn't contain any information that lets you backtrack to the artist if the post is deleted. Nor does it contain the title of the post.
So on FA, it's useful to provide 3 URLs for a post:
http://www.furaffinity.net/user/mkaz/ <-- artist
http://www.furaffinity.net/view/21555272/ <-- post
http://d.facdn.net/art/mkaz/1477618954/1477618954.mkaz_buick-img282-b_copy-small.jpg <-- file name

Because the Source field has room for 5 lines, this works if you only have a single source.
But if there are multiple sources, you run out of space very fast.

What part(s) of the site page(s) are affected?
Posts

You posted this into the old feature request thread, but it apparently never got its own thread?
forum #184178

So the problem is that when there's 5 sources, you can't directly visit the artist?

That doesn't sound very logical. If a post has 5 sources, then it's unlikely that the artist wouldn't be known, or that you would be unable to visit them one way or another.

Btw, the source was never supposed to take you to the artist.

Delian said:
So the problem is that when there's 5 sources, you can't directly visit the artist?

That doesn't sound very logical. If a post has 5 sources, then it's unlikely that the artist wouldn't be known, or that you would be unable to visit them one way or another.

Btw, the source was never supposed to take you to the artist.

Post, artist, direct image. Those are the three sources we typically like.
However, a lot of artists have several profiles. Even if you exclude the direct artist link (which should be included because there won't be a link on a dead page), that's still only three sources, one of which has to exclude the direct link, or four no-directs with one direct. Furaffinity, inkbunny, twitter, tumblr, furrynetwork, pixiv, deviantart, there's plenty of galleries available that we can't just link an artist to all of them due to the lack of enough source field.

Furrin_Gok said:
Post, artist, direct image. Those are the three sources we typically like.
However, a lot of artists have several profiles. Even if you exclude the direct artist link (which should be included because there won't be a link on a dead page), that's still only three sources, one of which has to exclude the direct link, or four no-directs with one direct. Furaffinity, inkbunny, twitter, tumblr, furrynetwork, pixiv, deviantart, there's plenty of galleries available that we can't just link an artist to all of them due to the lack of enough source field.

But you could argue as well: E621 has an Artist Wiki and there is the space for Artist links probably unlimited. The problem is, of course, someone should integrate these links there and that is more difficult there than in the source field. What we can not forget are the pictures or games where there are even more artists than the 5 links. See Ponybrotel ID 1033698, there are dozens.

My idea would be to link to each Atrtist, 2 additional places for the or Die Bildlinks. Inkbunny Artist Link + 2 for image links, Furaffinity + 2 for image links, and so on. However one would have to change the quellool of e621 then very much.

In general I find the idea of Munkelzahn not wrong.