[tz] Reason for removal of several TZ

[Derick Rethans]

On Sun, 3 Dec 2017, Thomas M Steenholdt wrote:

> > Which things went belly up? Details might be helpful.
> 
> 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:
> 
> https://bugs.launchpad.net/ubuntu/+source/tzdata/+bug/1734967

PHP follows tzdata, and there are some quite false assumptions made in 
the thread in that bug report.

> A few of my own scripts that convert time between timezones started 
> misbehaving as they expect WGT and WGST to be valid abbreviations. 
> This is easy to fix, but there could be (and probably is) other places 
> where this could cause problems.

In applications, timezone abbreviations should really only be used for 
output, and not for recording which timezone a specific event happened 
in. Relying on the UTC offsets they are linked too is a flawed approach.

I have never been keen on the removal of these invented timezone 
abbreviations, but it *does* highlight that using them for conversions 
is very fragile. You should endavour to remove the reliance on these 
abbreviations.

cheers,
Derick
(The PHP Date/Time maintainer)
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