[tz] Extended data format

[Ian Abbott]

On 2013-09-05 17:43, Ian Abbott wrote:
> 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.

I also forgot to add that this =zone thing would also make the Link 
directive redundant, since a zone line of the form:

Zone Asia/Calcutta =Asia/Kolkata = =

could be treated the same as:

Link Asia/Kolkata Asia/Calcutta

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