[html5] r7733 - [e] (0) Add more commentary on time zones. Fixing https://www.w3.org/Bugs/Public [...]
whatwg at whatwg.org
whatwg at whatwg.org
Wed Mar 6 12:23:49 PST 2013
Author: ianh
Date: 2013-03-06 12:23:48 -0800 (Wed, 06 Mar 2013)
New Revision: 7733
Modified:
complete.html
index
source
Log:
[e] (0) Add more commentary on time zones.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=17857
Affected topics: HTML
Modified: complete.html
===================================================================
--- complete.html 2013-03-06 19:51:44 UTC (rev 7732)
+++ complete.html 2013-03-06 20:23:48 UTC (rev 7733)
@@ -19844,6 +19844,13 @@
<pre class=example><time>2011-11-12 14:54:39</time></pre>
<pre class=example><time>2011-11-12 14:54:39.929</time></pre>
+ <p class=note>Times with dates but without a time zone offset are useful for specifying events
+ that are observed at the same specific time in each time zone, throughout a day. For example,
+ the 2020 new year is celebrated at 2020-01-01 00:00 in each time zone, not at the same precise
+ moment across all time zones. For events that occur at the same time across all time zones, for
+ example a videoconference meeting, a <a href=#valid-global-date-and-time-string>valid global date and time string</a> is likely
+ more useful.</p>
+
</dd>
@@ -19857,6 +19864,12 @@
<pre class=example><time>-0800</time></pre>
<pre class=example><time>-08:00</time></pre>
+ <p class=note>For times without dates (or times referring to events that recur on multiple
+ dates), specifying the geographic location that controls the time is usually more useful than
+ specifying a time zone offset, because geographic locations change time zone offsets with
+ daylight savings time. In some cases, geographic locations even change time zone, e.g. when the
+ boundaries of those time zones are redrawn, as happened with Samoa at the end of 2011.</p>
+
</dd>
@@ -19904,6 +19917,14 @@
<pre class=example><time>2011-11-12 06:54:39-08:00</time></pre>
<pre class=example><time>2011-11-12 06:54:39.929-08:00</time></pre>
+ <p class=note>Times with dates and a time zone offset are useful for specifying specific
+ events, or recurring virtual events where the time is not anchored to a specific geographic
+ location. For example, the precise time of an asteroid impact, or a particular meeting in a
+ series of meetings held at 1400 UTC every day, regardless of whether any particular part of the
+ world is observing daylight savings time or not. For events where the precise time varies by the
+ local time zone offset of a specific geographic location, a <a href=#valid-local-date-and-time-string>valid local date and time
+ string</a> combined with that geographic location is likely more useful.</p>
+
</dd>
@@ -46088,7 +46109,7 @@
<td class=no> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
- </table><div class=impl>
+ </table><!--CLEANUP--><div class=impl>
<p>Some states of the <code title=attr-input-type><a href=#attr-input-type>type</a></code>
attribute define a <dfn id=value-sanitization-algorithm>value sanitization algorithm</dfn>.</p>
@@ -47303,6 +47324,13 @@
instead, the calendar application would have also had to explicitly
determine which time zone the user intended.</p>
+ <p>For events where the precise time is to vary as the user travels (e.g. "celebrate the new
+ year!"), and for recurring events that are to stay at the same time for a specific geographic
+ location even though that location may go in and out of daylight savings time (e.g. "bring the
+ kid to school"), the <code title=attr-input-type-datetime-local><a href="#local-date-and-time-state-(type=datetime-local)">datetime-local</a></code> type
+ combined with a <code><a href=#the-select-element>select</a></code> element (or other similar control) to pick the specific
+ geographic location to which to anchor the time would be more appropriate.</p>
+
</div>
Modified: index
===================================================================
--- index 2013-03-06 19:51:44 UTC (rev 7732)
+++ index 2013-03-06 20:23:48 UTC (rev 7733)
@@ -19844,6 +19844,13 @@
<pre class=example><time>2011-11-12 14:54:39</time></pre>
<pre class=example><time>2011-11-12 14:54:39.929</time></pre>
+ <p class=note>Times with dates but without a time zone offset are useful for specifying events
+ that are observed at the same specific time in each time zone, throughout a day. For example,
+ the 2020 new year is celebrated at 2020-01-01 00:00 in each time zone, not at the same precise
+ moment across all time zones. For events that occur at the same time across all time zones, for
+ example a videoconference meeting, a <a href=#valid-global-date-and-time-string>valid global date and time string</a> is likely
+ more useful.</p>
+
</dd>
@@ -19857,6 +19864,12 @@
<pre class=example><time>-0800</time></pre>
<pre class=example><time>-08:00</time></pre>
+ <p class=note>For times without dates (or times referring to events that recur on multiple
+ dates), specifying the geographic location that controls the time is usually more useful than
+ specifying a time zone offset, because geographic locations change time zone offsets with
+ daylight savings time. In some cases, geographic locations even change time zone, e.g. when the
+ boundaries of those time zones are redrawn, as happened with Samoa at the end of 2011.</p>
+
</dd>
@@ -19904,6 +19917,14 @@
<pre class=example><time>2011-11-12 06:54:39-08:00</time></pre>
<pre class=example><time>2011-11-12 06:54:39.929-08:00</time></pre>
+ <p class=note>Times with dates and a time zone offset are useful for specifying specific
+ events, or recurring virtual events where the time is not anchored to a specific geographic
+ location. For example, the precise time of an asteroid impact, or a particular meeting in a
+ series of meetings held at 1400 UTC every day, regardless of whether any particular part of the
+ world is observing daylight savings time or not. For events where the precise time varies by the
+ local time zone offset of a specific geographic location, a <a href=#valid-local-date-and-time-string>valid local date and time
+ string</a> combined with that geographic location is likely more useful.</p>
+
</dd>
@@ -46088,7 +46109,7 @@
<td class=no> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
- </table><div class=impl>
+ </table><!--CLEANUP--><div class=impl>
<p>Some states of the <code title=attr-input-type><a href=#attr-input-type>type</a></code>
attribute define a <dfn id=value-sanitization-algorithm>value sanitization algorithm</dfn>.</p>
@@ -47303,6 +47324,13 @@
instead, the calendar application would have also had to explicitly
determine which time zone the user intended.</p>
+ <p>For events where the precise time is to vary as the user travels (e.g. "celebrate the new
+ year!"), and for recurring events that are to stay at the same time for a specific geographic
+ location even though that location may go in and out of daylight savings time (e.g. "bring the
+ kid to school"), the <code title=attr-input-type-datetime-local><a href="#local-date-and-time-state-(type=datetime-local)">datetime-local</a></code> type
+ combined with a <code><a href=#the-select-element>select</a></code> element (or other similar control) to pick the specific
+ geographic location to which to anchor the time would be more appropriate.</p>
+
</div>
Modified: source
===================================================================
--- source 2013-03-06 19:51:44 UTC (rev 7732)
+++ source 2013-03-06 20:23:48 UTC (rev 7733)
@@ -20829,6 +20829,13 @@
<pre class="example"><time>2011-11-12 14:54:39</time></pre>
<pre class="example"><time>2011-11-12 14:54:39.929</time></pre>
+ <p class="note">Times with dates but without a time zone offset are useful for specifying events
+ that are observed at the same specific time in each time zone, throughout a day. For example,
+ the 2020 new year is celebrated at 2020-01-01 00:00 in each time zone, not at the same precise
+ moment across all time zones. For events that occur at the same time across all time zones, for
+ example a videoconference meeting, a <span>valid global date and time string</span> is likely
+ more useful.</p>
+
</dd>
@@ -20842,6 +20849,12 @@
<pre class="example"><time>-0800</time></pre>
<pre class="example"><time>-08:00</time></pre>
+ <p class="note">For times without dates (or times referring to events that recur on multiple
+ dates), specifying the geographic location that controls the time is usually more useful than
+ specifying a time zone offset, because geographic locations change time zone offsets with
+ daylight savings time. In some cases, geographic locations even change time zone, e.g. when the
+ boundaries of those time zones are redrawn, as happened with Samoa at the end of 2011.</p>
+
</dd>
@@ -20889,6 +20902,14 @@
<pre class="example"><time>2011-11-12 06:54:39-08:00</time></pre>
<pre class="example"><time>2011-11-12 06:54:39.929-08:00</time></pre>
+ <p class="note">Times with dates and a time zone offset are useful for specifying specific
+ events, or recurring virtual events where the time is not anchored to a specific geographic
+ location. For example, the precise time of an asteroid impact, or a particular meeting in a
+ series of meetings held at 1400 UTC every day, regardless of whether any particular part of the
+ world is observing daylight savings time or not. For events where the precise time varies by the
+ local time zone offset of a specific geographic location, a <span>valid local date and time
+ string</span> combined with that geographic location is likely more useful.</p>
+
</dd>
@@ -53618,6 +53639,7 @@
</table>
+<!--CLEANUP-->
<div class="impl">
<p>Some states of the <code title="attr-input-type">type</code>
@@ -55049,6 +55071,13 @@
instead, the calendar application would have also had to explicitly
determine which time zone the user intended.</p>
+ <p>For events where the precise time is to vary as the user travels (e.g. "celebrate the new
+ year!"), and for recurring events that are to stay at the same time for a specific geographic
+ location even though that location may go in and out of daylight savings time (e.g. "bring the
+ kid to school"), the <code title="attr-input-type-datetime-local">datetime-local</code> type
+ combined with a <code>select</code> element (or other similar control) to pick the specific
+ geographic location to which to anchor the time would be more appropriate.</p>
+
</div>
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