[tz] Extended data format

[Ian Abbott]

On 2013-09-05 15:46, Andy Lipscomb wrote:
> It seems, based on the discussions, that one desired feature of an
> "extended" notation is to be able to say "this zone is like that
> other zone during period X." Herein, a suggestion for notation to
> express that relation:
>
> In a line of the zone record, the GMTOFF, RULES, and FORMAT fields
> may consist of an equal sign followed by the name of a zone. This has
> the meaning "use the data for the named zone in this zone as well."
> An equal sign standing alone repeats the most recent zone explicitly
> named in an equals-reference (which must be within the current zone
> record).
>
> Examples, using zones already in the database, follow:
>
> Zone America/North_Dakota/New_Salem -6:45:39 - LMT 1883 Nov 18 12:14:21
>      -7:00    US    M%sT    2003 Oct 26 02:00
>      -6:00    US    C%sT
>
> would in this notation be expressed as
>
> Zone America/North_Dakota/New_Salem -6:45:39 - LMT 1883 Nov 18 12:14:21
>      =America/Denver        =    =    2003 Oct 26 02:00
>      =America/Chicago       =    =
>
> And America/Shiprock could be represented as
>
> Zone America/Shiprock =America/Denver = NNT
>
> (meaning that it always follows Denver's offset and DST rules, but
> uses the abbreviation NNT--the phrase "Navajo Nation Time" is in
> use).

I guess such =zone references should refer to a zone earlier in the same 
file to keep things simple, i.e. no forward or external references.

-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti at mev.co.uk>        )=-
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