In order for a mintmark to be a RPM, there needs to be a spread between the punches. A mintmark can be enlarged and still not show a spread:
This one is not a RPM, no spread is showing of the punches:
Note on this one, they got to close to the digit, then moved it lower and still too close, and then a third location was decided. Thus a 1955-S S/S/S RPM-001 South.
1959-D D/D/D/D S-S-S-N. Note the line on the lower loop. That is the North on the lower loop. 1959-D RPM-009.
So your are seeing that the above item it not showing a mintmark punch spread. But is really contact marks on the mintmark.(Damage is never a plus for a coin)
Note on this one with the 3-D affect.
You can see clearly the two different punches.
Also on the serifs of the mintmarks you can see a split on the edges of the mintmark:
A rotated mintmark:
Look similar to a tilted RPM, but note the upright, with the curve on it. That is called a rotated punch issue.
Also RPMs are in directions:
The tilted are the most common to find and the hardest to identify. To match up a RPM, first consider location as that is the first step. Regardless on how close it looks like a matching RPM, the location is the determining factor. Also on the split serifs, need to also match to the exact same same/angle of the mintmark. A lot involved on determining the correct number. Takes time and patience to determine if they are a match, or not? So I hope this widens the horizons a bit. CoopHome
: RPMs what are they and why is spread so important on a RPM?