It appears that Parks On The Air is changing their park prefixes. In the United States, a park was identified with a K prefix. That now should be US- to indicate a park within the United States. Canada used to begin their park numbers with a VE-. They should now be starting with a CA-. As I understand it, the numeric codes for the parks should still be the same. Millerton Lake was K-8325 and should now be US-8325.
I have to assume that other country park prefixes will also be changing, but I have not seen a comprehensive listing.
Remember, if you are using a voice recording to call CQ Parks On The Air, you will want to update your voice recording to accurately reflect the new prefixes.
73
Harvey
KM6YFD