Hi Jochen,
Thanks for pointing me to your solution! I now realize that there is no strict validation of the date fields in Dataverse other than that characters like the -sign are not allowed.
I'm wondering if there is a best-practice recommendation on how to represent BC dates in the ISO 8601 standard, which I guess, underlies the date fields in the Dataverse metadata schemas. The Wikipedia article on ISO 8601 says the following:
To represent years before 0000 or after 9999, the standard also permits the expansion of the year representation but only by prior agreement between the sender and the receiver.[20] An expanded year representation [±YYYYY] must have an agreed-upon number of extra year digits beyond the four-digit minimum, and it must be prefixed with a + or − sign instead of the more common AD/BC (or CE/BCE) notation; by convention 1 BC is labelled +0000, 2 BC is labeled −0001, and so on.
Since + and - signs are not allowed in Dataverse date fields, BC seems to be the next best solution. My next question would then be: Is there a best-practice recommendation on how to represent time spans ranging from a BC year to an AD year? The heiDATA dataset indicates the dates in the following way: Start: 99BC ; End: 0550. Another variant would be Start: 99BC ; End: 550AD. Any ideas about which of these (or other alternatives) we should prefer?
Best, Philipp