[tz] Introduce Etc/UTC+x timezones?

Guy Harris gharris at sonic.net
Sat Apr 22 00:45:43 UTC 2023

On Apr 21, 2023, at 4:30 PM, Paul Gilmartin via tz <tz at iana.org> wrote:
> On 4/21/23 16:02:58, Guy Harris wrote:
>> If they have tools that support a proper UI for selecting tzdb regions, tell them your location and, if the UI doesn't recognize Suffolk, Montana or wherever you are, give them the location of a nearby city large enough to be notable.
>    ...
> Then I thought my Contact card is a reasonable place to keep this. So:
> <https://datatracker.ietf.org/doc/html/rfc6350#section-6.5.1>
> Internet Engineering Task Force (IETF)                      S. Perreault
> Request for Comments: 6350                                      Viagenie
>                       vCard Format Specification
> ...
> 6.5.1.  TZ
>   Purpose:  To specify information related to the time zone of the
>      object the vCard represents.
>   ...
>   Special notes:  It is expected that names from the public-domain
>      Olson database [TZ-DB] will be used, but this is not a
>      restriction.  See also [IANA-TZ].
> A deprecated interface

What's deprecated here?  (Presumably not tzids; vCard format appears to be one of those text-based-but-not-optimized-for-human-consumption formats that's primarily intended to be used in machine-to-machine communication, not human-to-machine or machine-to-human communication, so it's OK for it to use a tzid, also primarily intended to be consumed and produced by machines rather than directly used or generated by humans.)

>   Examples:
>     TZ:Raleigh/North America
> ...
> And an incorrect example.

"It is expected that names from the public-domain Olson database [TZ-DB] will be used, *but this is not a restriction*.", so Raleigh/North America is a valid TZ value according to RFC 6350.

Note that the TZ parameter can change even if, for example, the GEO parameter doesn't change, if you're in Wherever and Wherever decides to separate into West Whatever and East Whatever, with one of the two resulting Whatevers decides to have a new offset-from-UTC or a different set of DST rules, so that a bit of the tzdb region containing Whatever becomes a new tzdb region.  So I'm not sure it's a good idea to put it into a vCard.  With an appropriate mapping function, GEO would work better.

> How does one correct an RFC?

Either file an erratum:


or get involved with the group that developed it and push them to make an update (starting as an I-D) - that might be CalConnect, in this case:


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