I've spotted a couple of coins including
https://en.numista.com/catalogue/pieces72767.html
where an entry of ND (no date) in conjunction with the AH calendar leads to an AD date of 622 appearing, thus messing up the order in which coins are listed. I'm guessing this is a bug in the conversion from AH to AD (treating ND as "AH 0"). Can this be fixed?
