Re: [Cbor] draft-ietf-cbor-date-tag-02 - handling of time zone offsets

[Thiago Macieira <[e-mail]>]

On Wednesday, 1 July 2020 09:23:30 PDT Carsten Bormann wrote:
> I’m citing this as an example where a calendar date was chosen entirely by
> fiat, not based on the exact time of the actual event as adjusted for a
> specific place/time zone.  It does make sense to separate calendar dates
> from day-length periods anchored on a time scale, and this document is
> about representing calendar dates in CBOR.

What we need is a way to represent dates with and without a timezone 
information. If a timezone is absent, it needs to be inferred from context, 
such as birthdays as discussed, and is usually interpreted as local time.

Unix Timestamps have implied UTC (suitably un-corrected for leap seconds, 
whatever) and RFC 3339 or ISO 8601 timestamps have a way of representing a 
timezone or its absence, including dates without time.

Can you explain why we need these two new tags? Why doesn't it suffice to use 
tags 0 and 1? It is possible to use a date without a time with tag 0, after 
all.

I also question assigning a low tag number for the number-of-days-since-1970. 
That's not standardising existing practice, it's inventing a new format.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel System Software Products