I think it would help to confine this discussion to the requested issue, which is zero and negative years in currently defined calendars. A refinement of the "Gregorian" label is a good topic, but I should not have injected it into this discussion.
Also a full discussion of alternate date formats in the reference string is complicated. Can we please defer that to a future issue, when needed? I wholeheartedly support new calendar names that are explicit and mathematically well-defined. It is relevant to mention those ideas here. However, can we also put off their resolution to new issues, as needed? Let's see if we have some consensus so far on the following, acknowledging some previous agreement above. * For the reference date in the units string, continue to assume that the year number is easily recognizable and parseable. (There are currently no CF explicit format rules. We assume something like the UDUNITS delimited format shown in [section 4.4 Time Coordinate](http://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#time-coordinate). * Rules will be added to explicitly allow zero and negative year numbers in the reference date. A negative year number will be indicated by a preceding minus sign, with no other adornment. * To handle all possible cases, the interpretation of zero and negative year numbers will be explicitly defined for each defined CF calendar type. * For the current `standard` and `julian` calendars (and synonyms), zero and negative years will be **deprecated** for multiple reasons. * For the current `360_day`, `365_day`, and `366-day` calendars (and synonyms), year numbering will be the complete set of integers, including zero and negative. `Proleptic_gregorian` is problematical. Let's talk about that more later. Agreed so far? -- 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-705755303 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.
