Here is a 1997 D cent with what appears to be several die clashes, or is it something else like a different form of a plating blister? There is a thick line below the T in UNITED on the reverse. There are also zig-zag-shaped clashes in the bay left of Lincoln, a single clash extending from Lincoln's bay to the last bay over to the right, and finally a last clash on the last bay at the top going diagonal.
The NW/SE diagonal raised lines you see are die scrapes. Probably due to feeder fingers. See here: http://www.error-ref.com/die-scrapes/
Ahh ok, so the thick one underneath United is just a common die scrape - I see a lot of those often on various coins, just more subtle. But the other ones inside the bays are not in a straight line, nor are they in the same direction as the die scrape outside the building. I think those are die clashes.
