Please help, few easy questions

alright, i am just learing about varietys/errors etc and was wondering what these mean
RPM, MPD, clashed dies, rotated dies
What are they? Please let me know
RPM, MPD, clashed dies, rotated dies
What are they? Please let me know
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MPD= misplaced date
Rotated dies are when the obverse and reverse dies are misaligned. On a United States coin, the reverse should be upside-down in relation to the obverse, if you know what I mean. If it is not, the dies were misaligned.
Clashed dies are something I would like to find a picture of, to properly explain...
a clashed die is when a pair of dies come together with no planchette between. This will leave an image of each on the other side which would then be reverese image on a coin struck with that die. Usually they get replaced or polished out. Occasionally you will find a coin with an image of the opposite side barely visible. Pretty cool when you find them
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