[tz] tzdb timezone names/identifiers and links (was: Add new timezone for Hanoi Capital, Vietnam)

[Michael H Deckers]

On 2019-02-19 19:35, Steve Allen wrote:

>
> The scope of IANA tzdb is, in short, to provide a way for POSIX-like
> systems to convert between internal system clock time_t values and
> local civil time in a way where a single choice is valid for all
> history since 1970.  This is reasonably well documented.



     Regardless how well tzdb is documented, one cannot say that
     tzdb data is very systematic. Compare the case of Asia/Hanoi
     with that of Europe/Busingen.

     Europe/Busingen was introduced into tzdb on 2013-02-27; it
     differs from Europe/Berlin since 1970, but it agrees with
     Europe/Zurich and was linked to it ever since.

     Only five years later, Asia/Hanoi was added to backzone; it
     differs from Asia/Ho_Chi_Minh since 1970, but agrees with
     Asia/Bangkok since 1955.

     Why was Europe/Busingen not added to backzone as Asia/Hanoi
     was? Its history is known very precisely. Why was Asia/Hanoi
     not added as a link as Europe/Busingen was?

     It may well be that some changes in the theory file can be
     construed to explain the discrepancy, but I think that database
     data should reflect the current design principles, not
     their history. I may be a sloppy reader, but I do see what
     the theory.html file says about the two questions above.

     Michael Deckers.