[tz] Definition for timezone Asia/Urumqi and Asia/Kashgar, CST, and other questions about Chinese timezones.

Paul Eggert eggert at cs.ucla.edu
Sun Jan 1 10:54:52 UTC 2017

Robert Elz wrote:
>     From:        gfb hjjhjh <c933103 at gmail.com>
>   | 1. Currently, Asia/Urumqi and Asia/Kashgar are defined as UTC+6, covering
>   | most of Xinjiang and Tibet.
> I am not going to comment on this one, as I have no info on what people
> actually use in the affected areas, but if you can collect any evidence of
> what is actually done, that is the kind of information that we seek (direct
> evidence from affacted people is usually best).

Currently the commentary for Asia/Urumqi says that it covers "Xinjiang time, 
used by many in western China". Some people in western China use +06, some use 
+08 (Asia/Shanghai in our database), and the geographical boundary between the 
two sets of uses is indistinct.

>   | 4. as the name "Central Standard Time" in China was created by ROC,
> I always assmed that "CST" in China was "China Standard Time"

Yes, it's like KST and JST for Korea and Japan.

>   | 5. Why there are 5 different zones in China when the theory file say "if
>   | all the clocks in the region have agreed since 1970, don't bother to
>   | inclide more than one location even if subregions' clocks disagreed before
>   | 1970" ?
> We don't generally create a new timezone if the only difference we have is
> pre 1970, but sometimes...  There have been zome zone mergers because of this
> (which personally I do not like),   Basically, more accurate timezones are
> better, provided the data is correct - the big cost is in maintenance
> (a change might affect several zones, rather than just one).

Time zones like Asia/Kashgar and Asia/Harbin are present only for backward 
compatibility with earlier versions of the database, which (mistakenly) had 
different sets of time zone rules since 1970 for these locations. When we 
discovered the error, we discarded the incorrect data and created 
backward-compatibility links for the erroneously-created zones. Some tzdb 
installations don't install the backward-compatibility links and therefore do 
not have these erroneously-created zones.

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