[] (0) Change what was non-normatively implied to be proleptic UTC to…

… explicitly and normatively be proleptic UT1. Fixing http://www.w3.org/Bugs/Public/show_bug.cgi?id=11616 git-svn-id: http://svn.whatwg.org/webapps@5913 340c8d12-0b0e-0410-8428-c7bf67bfef74
whatwg · Feb 25, 2011 · 0309896 · 0309896
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diff --git a/complete.html b/complete.html
@@ -5097,16 +5097,25 @@ <h5 id=global-dates-and-times><span class=secno>2.5.5.5 </span>Global dates and
   zones is -12:00 to +14:00, and the minutes component of offsets of
   actual time zones is always either 00, 30, or 45.</p>
 
+  <p>Times in dates before the formation of UTC in the mid twentieth
+  century must be expressed and interpreted in terms of UT1
+  (contemporary Earth solar time at the 0&deg; longitude), not UTC
+  (the approximation of UT1 that ticks in SI seconds). Time before the
+  formation of time zones must be expressed and interpeted as UT1
+  times with explicit time zones that approximate the contemporary
+  difference between the appropriate local time and the time observed
+  at the location of Greenwich, London.</p>
+
   <div class=example>
 
    <p>The following are some examples of dates written as <a href=#valid-global-date-and-time-string title="valid global date and time string">valid global date and
    time strings</a>.</p>
 
    <dl><dt>"<code>0037-12-13T00:00Z</code>"</dt>
 
-    <dd>Midnight UTC on the birthday of Nero (the Roman Emperor). See
-    below for further discussion on which date this actually
-    corresponds to.</dd>
+    <dd>Midnight in areas using London time on the birthday of Nero
+    (the Roman Emperor). See below for further discussion on which
+    date this actually corresponds to.</dd>
 
     <dt>"<code>1979-10-14T12:00:00.001-04:00</code>"</dt>
 
@@ -5127,21 +5136,27 @@ <h5 id=global-dates-and-times><span class=secno>2.5.5.5 </span>Global dates and
     zero-padded. The date "37-12-13" would not be a valid date.</li>
 
     <li>To unambiguously identify a moment in time prior to the
-    introduction of the Gregorian calendar, the date has to be first
-    converted to the Gregorian calendar from the calendar in use at
-    the time (e.g. from the Julian calendar). The date of Nero's birth
-    is the 15th of December 37, in the Julian Calendar, which is the
-    13th of December 37 in the proleptic Gregorian Calendar.</li> <!--
-    This might not be true. I can't find a reference that gives his
-    birthday with an explicit statement about the calendar being
-    used. However, it seems unlikely that it would be given in the
-    Gregorian calendar, so I assume sites use the Julian one. -->
+    introduction of the Gregorian calendar (insofar as moments in time
+    before the formation of UTC can be unambiguously identified), the
+    date has to be first converted to the Gregorian calendar from the
+    calendar in use at the time (e.g. from the Julian calendar). The
+    date of Nero's birth is the 15th of December 37, in the Julian
+    Calendar, which is the 13th of December 37 in the proleptic
+    Gregorian Calendar.</li> <!-- This might not be true. I can't find
+    a reference that gives his birthday with an explicit statement
+    about the calendar being used. However, it seems unlikely that it
+    would be given in the Gregorian calendar, so I assume sites use
+    the Julian one. -->
 
     <li>The time and time-zone offset components are not optional.</li>
 
     <li>Dates before the year one can't be represented as a datetime
     in this version of HTML.</li>
 
+    <li>Times of specific events in ancient times are, at best,
+    approximations, since time was not well coordinated or measured
+    until relatively recent decades.</li>
+
     <li>Time-zone offsets differ based on daylight savings time.</li>
 
    </ul></div>

diff --git a/index b/index
@@ -5077,16 +5077,25 @@ a.setAttribute('href', 'http://example.com/'); // change the content attribute d
   zones is -12:00 to +14:00, and the minutes component of offsets of
   actual time zones is always either 00, 30, or 45.</p>
 
+  <p>Times in dates before the formation of UTC in the mid twentieth
+  century must be expressed and interpreted in terms of UT1
+  (contemporary Earth solar time at the 0&deg; longitude), not UTC
+  (the approximation of UT1 that ticks in SI seconds). Time before the
+  formation of time zones must be expressed and interpeted as UT1
+  times with explicit time zones that approximate the contemporary
+  difference between the appropriate local time and the time observed
+  at the location of Greenwich, London.</p>
+
   <div class=example>
 
    <p>The following are some examples of dates written as <a href=#valid-global-date-and-time-string title="valid global date and time string">valid global date and
    time strings</a>.</p>
 
    <dl><dt>"<code>0037-12-13T00:00Z</code>"</dt>
 
-    <dd>Midnight UTC on the birthday of Nero (the Roman Emperor). See
-    below for further discussion on which date this actually
-    corresponds to.</dd>
+    <dd>Midnight in areas using London time on the birthday of Nero
+    (the Roman Emperor). See below for further discussion on which
+    date this actually corresponds to.</dd>
 
     <dt>"<code>1979-10-14T12:00:00.001-04:00</code>"</dt>
 
@@ -5107,21 +5116,27 @@ a.setAttribute('href', 'http://example.com/'); // change the content attribute d
     zero-padded. The date "37-12-13" would not be a valid date.</li>
 
     <li>To unambiguously identify a moment in time prior to the
-    introduction of the Gregorian calendar, the date has to be first
-    converted to the Gregorian calendar from the calendar in use at
-    the time (e.g. from the Julian calendar). The date of Nero's birth
-    is the 15th of December 37, in the Julian Calendar, which is the
-    13th of December 37 in the proleptic Gregorian Calendar.</li> <!--
-    This might not be true. I can't find a reference that gives his
-    birthday with an explicit statement about the calendar being
-    used. However, it seems unlikely that it would be given in the
-    Gregorian calendar, so I assume sites use the Julian one. -->
+    introduction of the Gregorian calendar (insofar as moments in time
+    before the formation of UTC can be unambiguously identified), the
+    date has to be first converted to the Gregorian calendar from the
+    calendar in use at the time (e.g. from the Julian calendar). The
+    date of Nero's birth is the 15th of December 37, in the Julian
+    Calendar, which is the 13th of December 37 in the proleptic
+    Gregorian Calendar.</li> <!-- This might not be true. I can't find
+    a reference that gives his birthday with an explicit statement
+    about the calendar being used. However, it seems unlikely that it
+    would be given in the Gregorian calendar, so I assume sites use
+    the Julian one. -->
 
     <li>The time and time-zone offset components are not optional.</li>
 
     <li>Dates before the year one can't be represented as a datetime
     in this version of HTML.</li>
 
+    <li>Times of specific events in ancient times are, at best,
+    approximations, since time was not well coordinated or measured
+    until relatively recent decades.</li>
+
     <li>Time-zone offsets differ based on daylight savings time.</li>
 
    </ul></div>

diff --git a/source b/source
@@ -4386,6 +4386,15 @@ a.setAttribute('href', 'http://example.com/'); // change the content attribute d
   zones is -12:00 to +14:00, and the minutes component of offsets of
   actual time zones is always either 00, 30, or 45.</p>
 
+  <p>Times in dates before the formation of UTC in the mid twentieth
+  century must be expressed and interpreted in terms of UT1
+  (contemporary Earth solar time at the 0&deg; longitude), not UTC
+  (the approximation of UT1 that ticks in SI seconds). Time before the
+  formation of time zones must be expressed and interpeted as UT1
+  times with explicit time zones that approximate the contemporary
+  difference between the appropriate local time and the time observed
+  at the location of Greenwich, London.</p>
+
   <div class="example">
 
    <p>The following are some examples of dates written as <span
@@ -4396,9 +4405,9 @@ a.setAttribute('href', 'http://example.com/'); // change the content attribute d
 
     <dt>"<code>0037-12-13T00:00Z</code>"</dt>
 
-    <dd>Midnight UTC on the birthday of Nero (the Roman Emperor). See
-    below for further discussion on which date this actually
-    corresponds to.</dd>
+    <dd>Midnight in areas using London time on the birthday of Nero
+    (the Roman Emperor). See below for further discussion on which
+    date this actually corresponds to.</dd>
 
     <dt>"<code>1979-10-14T12:00:00.001-04:00</code>"</dt>
 
@@ -4423,21 +4432,27 @@ a.setAttribute('href', 'http://example.com/'); // change the content attribute d
     zero-padded. The date "37-12-13" would not be a valid date.</li>
 
     <li>To unambiguously identify a moment in time prior to the
-    introduction of the Gregorian calendar, the date has to be first
-    converted to the Gregorian calendar from the calendar in use at
-    the time (e.g. from the Julian calendar). The date of Nero's birth
-    is the 15th of December 37, in the Julian Calendar, which is the
-    13th of December 37 in the proleptic Gregorian Calendar.</li> <!--
-    This might not be true. I can't find a reference that gives his
-    birthday with an explicit statement about the calendar being
-    used. However, it seems unlikely that it would be given in the
-    Gregorian calendar, so I assume sites use the Julian one. -->
+    introduction of the Gregorian calendar (insofar as moments in time
+    before the formation of UTC can be unambiguously identified), the
+    date has to be first converted to the Gregorian calendar from the
+    calendar in use at the time (e.g. from the Julian calendar). The
+    date of Nero's birth is the 15th of December 37, in the Julian
+    Calendar, which is the 13th of December 37 in the proleptic
+    Gregorian Calendar.</li> <!-- This might not be true. I can't find
+    a reference that gives his birthday with an explicit statement
+    about the calendar being used. However, it seems unlikely that it
+    would be given in the Gregorian calendar, so I assume sites use
+    the Julian one. -->
 
     <li>The time and time-zone offset components are not optional.</li>
 
     <li>Dates before the year one can't be represented as a datetime
     in this version of HTML.</li>
 
+    <li>Times of specific events in ancient times are, at best,
+    approximations, since time was not well coordinated or measured
+    until relatively recent decades.</li>
+
     <li>Time-zone offsets differ based on daylight savings time.</li>
 
    </ul>