<div>For the areas in which existing tz database zones apply, Eric Muller's shapefiles at <a href="http://efele.net/maps/tz/world/">http://efele.net/maps/tz/world/</a> are public domain and would certainly provide a good starting point for any project seeking to enhance historical accuracy.</div>
<div><br clear="all">--<br>Tim Parenti<br><br><br><br></div>
<div class="gmail_quote">On Thu, Aug 18, 2011 at 11:15, Alois Treindl <span dir="ltr"><<a href="mailto:alois@astro.ch">alois@astro.ch</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">
<div class="im">On 18.08.11 04:46, Paul Eggert wrote:<br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">Yes, the situation in China was quite different back then,<br>but luckily for us our cutoff date is the POSIX epoch<br>
of 1970-01-01 00:00:00 UTC. In the tz database we don't<br>create a new zone merely because some locality had<br>different clocks before 1970. If we did, we'd need<br>hundreds of zones for Indiana alone.<br></blockquote>
<br></div>We (a group of timezone researchers for astrology purposes) are planning to do exactly that, create the required 300+ Indiana zones (Shanks/Pottenger uses 350+ but is not complete), to cover pre-1970 Indiana timezone history.<br>
<br>It will take a lot of work and we understand that these extra zone will not get entry into standard tzdata file distribution. But I think if we maintain a separate 'history' zone fileset outside, tzcode will work with these extra zones of we include them in the zic compilation step.<br>
<br>For China as well.<br><br>Writing the zone files is only one part of the work, the other is describing precisely for which area the extra zones apply, and which area is covered by the existing standard tzdata zones.<br>
<br><br></blockquote></div><br>