[tz] Adding Asia/Beijing timezone into the database

Philip Newton philip.newton at gmail.com
Wed Dec 7 08:16:02 UTC 2011

On Wed, Dec 7, 2011 at 08:21, Daoming Qiu <qdaoming at gmail.com> wrote:
> "Beijing Time" is the standard time used for China region, so
>  it is very strange that tzdatabase doesn't have timezone called Asia/Beijing.

The database does not follow, in general, country lines but rather
regions that use the same timezone during the same period of time. And
because cities change their names less often than countries do, the
database usually uses city names (rather than country names) to
identify such timezone regions, and in general (in my understanding)
chooses the largest city within a timezone region to represent that
region. This favours Shanghai over Beijing.

You will note that there is also no America/Washington_DC, for
example, or Australia/Canberra, or America/Brasilia.

See also the "Theory" file in the tzcode distribution; this mentions
some of the things taken into account when choosing names of time
zones. (And it even has Shanghai/Beijing as an example: "Use the most
populous among locations in a country's time zone, e.g. prefer
`Shanghai' to `Beijing'.")

> Strongly suggest to add "Asia/Beijing" zone into the database,
> and its information is very similar with "Asia/Shanghai".

If it is only "similar", can you please provide information on when
Beijing used different time from Shanghai after January 1970? Then the
tz database can be corrected and completed.

Final disclaimer: I'm not a tz database maintainer and do not
represent anyone maintaining it or setting the rules. The above is my
understanding and interpretation.

Philip Newton <philip.newton at gmail.com>

More information about the tz mailing list