[Cbor] Two specifications on timestamps nearing WGLC

[Carsten Bormann <[e-mail]>]

In the SEDATE and CBOR working groups, two loosely related
specifications about timestamp formats for the Internet are being
readied:

* SEDATE WG: draft-ietf-sedate-datetime-extended defines the "Internet
  Extended Date/Time Formmt" (IXDTF), an extension to the widely used
  text-based RFC 3339 format that allows the addition of time-zone
  hints and other additional information (e.g., a preferred calendar
  format).  This has been discussed with communities that already have
  some form of these format extensions in use and is intended as the
  specification that provides a common standard for these.
  https://www.ietf.org/archive/id/draft-ietf-sedate-datetime-extended-06.html

* CBOR WG: draft-ietf-cbor-time-tag defines a few CBOR tags for
  timestamps, durations, and periods of time, going beyond the
  capabilities of the existing CBOR tags 0 (RFC3339) and 1 (POSIX
  time).  This specification allows the transport of SEDATE extensions
  in a CBOR time tag.
  https://www.ietf.org/archive/id/draft-ietf-cbor-time-tag-02.html

One item that is of particular interest to the wider community this
note addresses: We found an interoperability problem with the way
that RFC 3339 handles timestamps that do not want to provide a hint
about time zone offsets.  As a remedy, the IXDTF spec therefore
proposes to *update* RFC 3339.  The need for this was a surprise for
many of us, and a charter adjustment may be needed for the SEDATE WG
for this update to go forward.

Some of the details in the CBOR time tag may be of interest to the NTP
and TICTOC WGs, which are therefore also CCed.

Please reply to [e-mail] for wider comments (e.g., "this is not
the right way of doing this"), and to [e-mail] or [e-mail]
for more detailed comments specific to one of the specifications.
(The CBOR WG will have a chance to discuss any early input during its
2022-10-05 interim today.)