I am coming around to favoring a partial ISO 8601-2:2019 approach as described above by @peterkuma. Both ways of either counting or not counting year 0 could be supported with some minimal extension of the reference date notation, as initially suggested above by @martinjuckes. I have a suggested notation that I would like hold for later.
Let's continue to focus on the primary question of year numbers in the traditional CF format, without any new notation. By ISO 8601-2:2019, and if we agree, year zero and negative years are included. Now the interpretation for `proleptic_gregorian` is still undecided. I suggest that the current, unadorned `proleptic_gregorian` should include year zero and negative years for general scientific usage. I do not know of any data sets that have encoded zero or negative years in a conflicting way with `proleptic_gregorian`. Also there is precedent for this outside of CF; see the [Wikipedia article](https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar). @JonathanGregory, you proposed that years before 1 should be deprecated for `proleptic_gregorian`. Do you have a specific reason for preferring this? -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/cf-convention/cf-conventions/issues/298#issuecomment-716918210 This list forwards relevant notifications from Github. It is distinct from cf-metad...@cgd.ucar.edu, although if you do nothing, a subscription to the UCAR list will result in a subscription to this list. To unsubscribe from this list only, send a message to cf-metadata-unsubscribe-requ...@listserv.llnl.gov.
