What are KM numbers?

So I see some of my coins are pcgs graded with a KM number and some are not. What do these numbers mean?
Thanks in advance.
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So I see some of my coins are pcgs graded with a KM number and some are not. What do these numbers mean?
Thanks in advance.
Comments
Google KM coin numbers and you will get plenty of explanations.
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KM numbers are Krause-Mishler numbers and are used primarily for world coins. The various Krause-Mishler catalogs use the numbers.
What @291fifth said.
What Jim said