iCalendar UNTIL rule must be of the same type as DTSTART property?
<p>In <a href="https://www.rfc-editor.org/rfc/rfc5545#section-3.3.10" rel="nofollow noreferrer">iCalendar RFC 5545, section 3.3.10</a>, I see the following UNTIL parameter description:</p>
<blockquote>
<p>The value of the UNTIL rule part MUST have the same
value type as the &quot;DTSTART&quot; property.  Furthermore, if the
&quot;DTSTART&quot; property is specified as a date with local time, then
the UNTIL rule part MUST also be specified as a date with local
time.  If the &quot;DTSTART&quot; property is specified as a date with UTC
time or a date with local time and time zone reference, then the
UNTIL rule part MUST be specified as a date with UTC time.</p>
</blockquote>
<p>However, in <a href="https://www.rfc-editor.org/rfc/rfc5545#section-3.8.5.3" rel="nofollow noreferrer">3.8.5.3 Recurrence Rule</a> paragraph, UNTIL is always specified in UTC, regrdless of DTSTART property:</p>
<pre><code>   DTSTART;TZID=America/New_York:19970902T090000
   RRULE:FREQ=DAILY;UNTIL=19971224T000000Z

   DTSTART;TZID=America/New_York:19970902T090000
   RRULE:FREQ=WEEKLY;UNTIL=19971007T000000Z;WKST=SU;BYDAY=TU,TH
</code></pre>
<p>There are 5 of such examples in total.</p>
<p>I also found that at least 2 CalDAV clients (iOS and Mozilla Lightning) always submit UNTIL parameter in UTC, regardless of DTSTART property.</p>
<p>The only place where UNTIL must be always in UTC is RRULE in VTIMEZONE. Or am I not getting something?</p>