[tz] Relation between Time Zone Abbreviation and Offset in Asia

[Paul Eggert]

On 3/30/21 6:26 AM, Evgheni Antropov via tz wrote:
> is it correct to use Offset instead of Abbreviation or it will be fixed in future?

The offset is intended.

I invented the abbreviation "ICT" in 1993:

https://github.com/eggert/tz/commit/61315cadc3d0e8b4ef559539502a606cf58fc0f7

Back then, POSIX required alphabetic abbreviations and I thought it 
better to be consistent with POSIX so I invented abbreviations all over 
the world to fill in the blanks. However, I was uncomfortable with tzdb 
inventing rather than describing usage.

In 2001 POSIX was changed to allow numeric abbreviations and eventually 
(in version 2017a) tzdb was changed to use numeric abbreviations instead 
of the invented alphabetic ones. This change is described in the NEWS 
file, and tzdb's current practice for abbreviations is described here:

https://data.iana.org/time-zones/theory.html#abbreviations