On 10 Apr, 2013, at 19:04 , Peter Stagg <P.Stagg@bom.gov.au> wrote:
Only tree of the four states in the "Eastern Standard Timezone" have daylight savings and they only have it for aprox. four of the twelve months in the year. And as someone pointed out before many web sites unwittingly use the TZ Database data to automatically timestamp pages. So the frequency of use of "EST" is destined to be much higher then "EDT" and therefore the search is meaningless.
I have no particular interest in what Australian time zone abbreviations should have been, or should be going forward, but I'm a bit interested in the topic mentioned above. If I needed to interpret a timestamp recorded by sites which "unwittingly use" the TZ database the TZ database itself makes it clear what I would need to know to disambiguate it: I need to know where in Australia the timestamp was taken (and I need to hope the timestamp wasn't taken in the 2 hours per year which can't be disambiguated, though the TZ database does also tell me which 2 hours are unavoidably ambiguous). I understand the effect of the change proposed is to reduce the information I need to know to disambiguate future timestamps recorded via unwitting use of the TZ database to "Australia", and this seems useful to me independent of what terms people in Australia actually use (or used) to describe the the current time on their clocks. I would note, however, that the proposed patch doesn't just limit itself to reducing the ambiguity of future timestamps not yet recorded, it also changes the database information about the abbreviations used for historical timestamps produced by the TZ database. While the issue of what time zone abbreviations people in Australia might have preferred to use is for others to debate there can be no dispute about the abbreviations the TZ database has used for the last 20 years, nor is there any way to change that, but by altering that data one is effectively removing the information about the history of the database itself that one would need to know to interpret timestamps already recorded with the "unwitting use" of the TZ database. Is there a reason to change the historical TZ database abbreviations rather than just making a change which is applied going forward? You can't really fix what has already happened, and attempting to pretend that it didn't happen that way just seems to increase the ambiguities that people with a need to interpret old timestamps produced with old versions of the TZ database need to deal with while having no offsetting advantages that I can see. As a policy matter I'd prefer that the bar to changing past TZ database data was set much higher (i.e. should require evidence of factual errors rather than just issues of opinion) than the bar to making changes which only effect the future. Dennis Ferguson