Interesting. Seems to be 4 different areas where you see that appear. The one with the slight angle (1st pic) makes me think it's just Post Mint Damage.
I think the 1st & 2nd photos are PMD. Based on that, I don't think it matters what the others are, but I'm inclined to think the person who caused this was experimenting with clips using this coin. Chris
The vertical striations In Allan's #1 photo lead me to believe the clip theory may be justified. I've nothing to back that theory up with........just my gut.
Ken, look at the photo of the reverse. The cut in the #1 photo is shown in the 10 o'clock position. It is slanted across the edge which couldn't possibly be a clip. Chris
I say PMD. Am I seeing things or do the striations change orientation from pic 1 to pic 2 (vertical to horizontal)? Regardless, I say PMD.
I'd say it was filed down on four places 90 degrees apart to fit in some kind of holder. Jewelry/ring/necklace/etc.