Requested feature overview description.
Similar to how there is a reason field for the "Uploader requested removal", a field for the "Uncredited trace" would be incredibly useful. Wording is important here however, it should be something along the lines of "Proof" or "Evidence", not "Info", and a warning stating the FFD may be ignored if the field is empty and there is no comments about it.
This can easily be solved with the placeholder field on the input element, putting something along the lines of: "Post ID or link to original", and if the field is [parseInt(input).toString() === input], convert it to a post #1234 style link.

Why would it be useful?
Helps mods/janitors to know why a post was flagged as a trace. I've seen people flag posts more times than they should have without any other info other than it is a "trace".
Allowing a info field will increase the chances of the user properly providing the required info, allowing for FFDs to be cleared faster and easier.

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

• Post flagging.

Or change the flag reason from:
This post is an uncredited trace of another artist's work

To:
This post is an uncredited trace of another artist's work
Please add a comment with Post ID or link to original

+1 from me

do-it.com