[tz] Reason for removal of several TZ

Paul Eggert eggert at cs.ucla.edu
Mon Dec 4 07:35:33 UTC 2017

Thomas M Steenholdt wrote:
>  From what I've seen, PHP (on Ubuntu) had some hiccups and started
> mentioning Sao Paolo in my date/time outputs, because WGT/WGST was
> suddenly missing:

As I understand from 
<https://bugs.launchpad.net/ubuntu/+source/tzdata/+bug/1734967>, PHP attempts to 
guess the tzdb Zone name (e.g., "Europe/Berlin") from the abbreviation and UT 
offset, which is the sort of thing that we have long explicitly warned should 
not be done because abbreviations are ambiguous. Although you may now have 
noticed the problem with Western Greenland and Sao Paolo, surely other users can 
run into similar problems with (say) Algeria and Berlin. (Algeria and Germany 
have the same standard UT offset but differing DST rules, and in that respect 
are like western Greenland vs. southern Brazil.)

I'm afraid that the sources that you mention are derived from tzdata. Generally 
speaking, we're looking for general-interest English-language sources, such as 
newspapers, magazines, books and the like. A few tzdata-derived abbreviations 
have made it into popular usage, and we've kept them.

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