<div dir="ltr"><div class="gmail_extra"><br><div class="gmail_quote">On 16 February 2015 at 00:28, Paul Ganssle <span dir="ltr"><<a href="mailto:pganssle@gmail.com" target="_blank" onclick="window.open('https://mail.google.com/mail/?view=cm&tf=1&to=pganssle@gmail.com&cc=&bcc=&su=&body=','_blank');return false;">pganssle@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">Have there actually been any time zones that are not an even multiple of a whole minute since the advent of leap seconds? The only non whole minute time zone I know about is Dublin Mean Time, which hasn't been used since 1916.</blockquote></div><br>If I recall correctly, Africa/Monrovia is the only zone in the main files which has had an offset that is not an integer number of minutes at any point since 1970 (it was -0:44:30 until 1972-05). UTC was introduced in 1972, with the first leap second (as we know it today) coming at the end of 1972-06-30. So, no; this isn't a real concern in any existing zones.</div><div class="gmail_extra"><br></div><div class="gmail_extra">On 15 February 2015 at 09:12, <span dir="ltr"><<a href="mailto:random832@fastmail.us" target="_blank" onclick="window.open('https://mail.google.com/mail/?view=cm&tf=1&to=random832@fastmail.us&cc=&bcc=&su=&body=','_blank');return false;">random832@fastmail.us</a>></span> wrote:<br></div><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div id=":749" class="" style="overflow:hidden">Also, general question: is there any standard on how leap seconds are to<br>be handled in timezones that have an offset that is not a multiple of<br>one whole minute? What does tzcode do now?</div></blockquote></div><div class="gmail_extra"><br></div>In the interest of... well, interest ;) ...let's find out! Adding:<div class="gmail_extra"><font face="monospace, monospace">Zone<span class="" style="white-space:pre"> </span>Test/Foo<span class="" style="white-space:pre"> </span>0:00:30<span class="" style="white-space:pre"> </span>-<span class="" style="white-space:pre"> </span>FooST</font></div><div class="gmail_extra">to the data, and installing with <font face="monospace, monospace">make right_only</font>, we can perform a <font face="monospace, monospace">zdump</font>:</div><div class="gmail_extra"><br></div><div class="gmail_extra"><font face="monospace, monospace">$ zdump -c 2015,2016 -v Etc/UTC Asia/Tokyo Test/Foo</font></div><div class="gmail_extra"><font face="monospace, monospace">...</font></div><div class="gmail_extra"><font face="monospace, monospace">Etc/UTC Tue Jun 30 23:59:60 2015 UT = Tue Jun 30 23:59:60 2015 UTC isdst=0 gmtoff=0</font></div><div class="gmail_extra"><font face="monospace, monospace">Etc/UTC Wed Jul 1 00:00:00 2015 UT = Wed Jul 1 00:00:00 2015 UTC isdst=0 gmtoff=0</font></div><div class="gmail_extra"><span style="font-family:monospace,monospace">...</span></div><div class="gmail_extra"><span style="font-family:monospace,monospace">Asia/Tokyo Tue Jun 30 23:59:60 2015 UT = Wed Jul 1 08:59:60 2015 JST isdst=0 gmtoff=32400</span><br></div><div class="gmail_extra"><font face="monospace, monospace">Asia/Tokyo Wed Jul 1 00:00:00 2015 UT = Wed Jul 1 09:00:00 2015 JST isdst=0 gmtoff=32400</font></div><div class="gmail_extra"><span style="font-family:monospace,monospace">...</span></div><div class="gmail_extra"><span style="font-family:monospace,monospace">Test/Foo Tue Jun 30 23:59:60 2015 UT = Wed Jul 1 00:00:30 2015 FooST isdst=0 gmtoff=30</span><br></div><div class="gmail_extra"><font face="monospace, monospace">Test/Foo Wed Jul 1 00:00:00 2015 UT = Wed Jul 1 00:00:30 2015 FooST isdst=0 gmtoff=30</font></div><div class="gmail_extra"><font face="monospace, monospace">...</font></div><div class="gmail_extra"><br></div><div class="gmail_extra">So, it looks like it just keeps a constant offset (which is quite reasonable), even though in such cases it would explicitly require counting the same second twice (which is not quite so reasonable).</div><div class="gmail_extra"><br></div><div class="gmail_extra">I recalled seeing a proposed solution which took the opposite approach earlier on this list, which was to forsake the constant offset in favor of counting as normal, before "applying" the leap second at the end of the "local minute" which contained the UTC leap second. Upon further investigation, it seems that suggestion came from you, random832!</div><div class="gmail_extra"><a href="http://mm.icann.org/pipermail/tz/2013-September/020155.html">http://mm.icann.org/pipermail/tz/2013-September/020155.html</a><br></div><div class="gmail_extra"><br></div><div class="gmail_extra">So in terms of behavior for the purposes of documentation, those are the two options. But, again, I doubt this is going to matter for any practical purposes anytime soon, so I would expect tzcode will likely stay as it is with respect to this matter.</div><br clear="all"><div><div class="gmail_signature">--<br>Tim Parenti<br></div></div>
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