On 2018-06-22 17:29, Paul Eggert wrote:
On 06/22/2018 04:18 PM, Michael H Deckers via tz wrote:
I propose to record only what we really have learned since 2018e: the abbreviation PST for Manila time was legally acknowledged in 2013, and it was used later on by some newspapers.
Generally speaking, tzdb uses current abbreviations even for older timestamps. That is, tzdb is designed primarily for today's uses, such as a historian writing today about events long ago; it does not attempt to record the long-ago abbreviations, such as the abbreviation Filipinos back in (say) 1950 used to describe time back in 1950. In that sense, it is like modern historians who systematically use the Gregorian calendar even when writing about events that took place in Russia in 1914.
Partly this is to simplify maintenance. That is, it's not merely that tzdb is designed for today's uses; it's also that it's easier to keep track of today's abbreviations than to also keep track of historical abbreviations used in the past. This point is covered in <https://data.iana.org/time-zones/theory.html>, which gives the following guideline for abbreviations:
Use current abbreviations for older timestamps to avoid confusion. For example, in 1910 a common English abbreviation for time in central Europe was 'MEZ' (short for both "Middle European Zone" and for "Mitteleuropäische Zeit" in German). Nowadays 'CET' ("Central European Time") is more common in English, and the database uses 'CET' even for circa-1910 timestamps as this is less confusing for modern users and avoids the need for determining when 'CET' supplanted 'MEZ' in common usage.
TL;DR: it's hard enough finding reliable, accurate sources for time zone and STD/DST transition data, without adding the burden of also finding reliable, accurate sources for common English abbreviations used from 1970 or earlier ;^> -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada