<div dir="ltr"><div>The Shanks data often contain guesswork, and the abovementioned transition dates from LMT are almost certainly part of that guesswork.</div><div> </div><div>-------<br></div><div>This is true. Gary Christian (CEO Astrolabe) has admitted that time zone info represents "interpretations" trying to argue its copyrightability based on the idea that time zone data aren't "facts" (apparently not understanding the legal definition). Also the transitions from LMT to the onset of standard time is grossly underreported in the ACS Atlas. This data is nowhere near complete, but it would be nice to keep this info in the tzdb.</div>
<div> </div><div>From what I understand, the original research by Thomas Shanks et al involved going through local newspapers all over the globe looking for reports of time changes. Many times they would see a time for a baseball game stated and then a later game on another date with a different time format (or something similar), but not exact transition date and time for daylight savings onset, so they probably did an interpolation and preferred weekends for setting this change, but they guard this information as to exactly what criteria they used as a secret. Personally I think the data would have gained a lot more respect if they had cited their sources and found a way to highlight these uncertain periods both in book form and in software.</div>
<div> </div><div>It would have been nice if the IATASSIM had kept all its data going back to its founding.</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Sep 3, 2013 at 10:47 AM, Paul Eggert <span dir="ltr"><<a href="mailto:eggert@cs.ucla.edu" target="_blank">eggert@cs.ucla.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="im">Brian Inglis wrote:<br>
<br>
> merging zones with different Standard Time<br>
> start date loses useful historical data<br>
<br>
</div>That's not a problem for the proposed change,<br>
because in this particular case, no useful historical<br>
data are lost. There is no real evidence that the<br>
start dates actually differed. All we have is<br>
some guesswork from Shanks. The Shanks data often<br>
contain guesswork, and the abovementioned<br>
transition dates from LMT are almost certainly<br>
part of that guesswork.<br>
<br>
The associated time zone abbreviations are also guesswork<br>
(in this case, my guesswork and not Shanks'),<br>
so they do not contain any useful historical data<br>
either.<br>
</blockquote></div><br></div>