[tz] draft of change summary for next tz release

[Guy Harris]

On Sep 18, 2013, at 1:06 AM, Lester Caine <lester at lsces.co.uk> wrote:

> I'm trying to help with the idea of the addition of 'thousands' of timezones, and in the end if there is evidence for thousands in the USA then they simply need documenting anyway!

Perhaps they do, but whether that document needs to take the form of thousands of extra tzids is another matter.  If they do, we should definitely give packagers of the tzdb, such as OS vendors, the option of *not* providing those thousands of extra tzids.

> I would still like to tidy up 'backward' as well to actually contain dates that a particular alias was used from 'officially'.

As far as I'm concerned, "backward" should contain only links provided for backwards-compatibility reasons when a tzid name change occurred, e.g.

Link	America/Halifax		Canada/Atlantic
Link	America/Winnipeg	Canada/Central
Link	America/Regina		Canada/East-Saskatchewan
Link	America/Toronto		Canada/Eastern
Link	America/Edmonton	Canada/Mountain
Link	America/St_Johns	Canada/Newfoundland
Link	America/Vancouver	Canada/Pacific
Link	America/Regina		Canada/Saskatchewan
Link	America/Whitehorse	Canada/Yukon
Link	America/Anchorage	US/Alaska
Link	America/Adak		US/Aleutian
Link	America/Phoenix		US/Arizona
Link	America/Chicago		US/Central
Link	America/Indiana/Indianapolis	US/East-Indiana
Link	America/New_York	US/Eastern
Link	Pacific/Honolulu	US/Hawaii
Link	America/Indiana/Knox	US/Indiana-Starke
Link	America/Detroit		US/Michigan
Link	America/Denver		US/Mountain
Link	America/Los_Angeles	US/Pacific

and, I think:

Link	America/Havana		Cuba
Link	Africa/Cairo		Egypt
Link	Europe/Dublin		Eire
Link	Europe/London		GB
Link	Asia/Hong_Kong		Hongkong
Link	Atlantic/Reykjavik	Iceland
Link	Asia/Tehran		Iran
Link	Asia/Jerusalem		Israel
Link	America/Jamaica		Jamaica
Link	Asia/Tokyo		Japan
Link	Pacific/Kwajalein	Kwajalein
Link	Africa/Tripoli		Libya
Link	America/Tijuana		Mexico/BajaNorte
Link	America/Mazatlan	Mexico/BajaSur
Link	America/Mexico_City	Mexico/General
Link	Pacific/Auckland	NZ
Link	Pacific/Chatham		NZ-CHAT
Link	America/Denver		Navajo
Link	Asia/Shanghai		PRC
Link	Europe/Warsaw		Poland
Link	Europe/Lisbon		Portugal
Link	Asia/Taipei		ROC
Link	Asia/Seoul		ROK
Link	Asia/Singapore		Singapore
Link	Europe/Istanbul		Turkey

which are, I think, backwards-compatibility links introduced with the naming convention change.

The only historical information associated with them relates to the history of the tzdb *itself*, and that's not of any use to people using the tzdb.

There are also backwards-compatibility links introduced due to city name changes, e.g. not using "foreigner's" names for the city, e.g.

Link	Africa/Asmara		Africa/Asmera
Link	Asia/Kolkata		Asia/Calcutta
Link	Asia/Chongqing		Asia/Chungking
Link	Asia/Dhaka		Asia/Dacca
Link	Asia/Kathmandu		Asia/Katmandu
Link	Asia/Macau		Asia/Macao

The only historical information associated with them is the date when the old names were deprecated, which has nothing to do with the history of time zones.

Some links in "backwards" should perhaps be moved to other files.  (The politically-sensitive links might fall into that category.)