All of the photos of the 1949-D/S nickels I've found online are really shadowed, and also this one has a weird line that goes thru the middle and outside of the D. Help lol. P.S. this whole file uploaded thing.holy Windows 98, Batman!
It is not a D/S OMM. I do think it is an RPM and unlisted. I've marked up your pic, looks to be heading east, with a slight hook showing northeast and a nice straight line of the west vertical side of the RPM, showing inside the mm.
Looks more like a die wear issue more. It is the wave of die flow. When the die flow is taller than a die scratch, it is not a RPM.
Inside a device, a Die scratch can exist a lot longer there. Just a die scratch on an aging die. If the mintmark looks that affected, why is not the area in question also affected as strongly? It is because it was a die event die polishing scratch.
I thought about that, coop and you may be right but this one looked good enough, in my opinion, to send in. The lighting may be a factor too, sometimes makes things look more extreme that what they actually are.