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286.txt
108 lines (84 loc) · 5.35 KB
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286.txt
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[FIG(quote)[
[FIGCAPTION[
[1] [CITE@en-US[Floating time zone support? | Communities]]
( ([TIME[2016-06-15 12:46:58 +09:00]]))
<https://discussions.apple.com/thread/1080972?start=0&tstart=0>
]FIGCAPTION]
> iCal has a handy feature where you can set the time zone of an event to "Floating". What this means is that the event is no longer tied to a specific time zone. So, let's say you want to schedule lunch at 12pm every day no matter where in the world you are, you set the time zone to floating, and that way you don't get an alert to have lunch at 4am if you're visiting another country.
]FIG]
[FIG(quote)[
[FIGCAPTION[
[2] [CITE[DateTime::TimeZone::Floating - search.cpan.org]]
( ([TIME[2016-06-15 12:47:27 +09:00]]))
<http://search.cpan.org/dist/DateTime-TimeZone/lib/DateTime/TimeZone/Floating.pm>
]FIGCAPTION]
> This class is used to provide the DateTime::TimeZone API needed by DateTime.pm, but for floating times, as defined by the RFC 2445 spec. A floating time has no time zone, and has an effective offset of zero.
]FIG]
[FIG(quote)[
[FIGCAPTION[
[3] [CITE[DateTime::TimeZone - search.cpan.org]]
( ([TIME[2016-06-15 12:48:15 +09:00]]))
<http://search.cpan.org/dist/DateTime-TimeZone/lib/DateTime/TimeZone.pm#USAGE>
]FIGCAPTION]
> If the "name" parameter is "floating", then a DateTime::TimeZone::Floating object is returned. A floating time zone does have any offset, and is always the same time. This is useful for calendaring applications, which may need to specify that a given event happens at the same local time, regardless of where it occurs. See RFC 2445 for more details.
]FIG]
[FIG(quote)[
[FIGCAPTION[
[4] [CITE@en-US[Working with Time Zones]]
( ([TIME[2011-07-05 21:14:06 +09:00]]))
<https://www.w3.org/TR/timezone/#floating>
]FIGCAPTION]
> Some observed time values are not related to a specific moment in incremental time. Instead, they need to be combined with local information to determine a range of acceptable incremental time values. We refer to these sorts of time values as "floating times" because they are not fixed to a specific incremental time value. Floating times are not attached and should never be attached to a particular time zone.
> Some examples of floating time events include a user’s birth date, a document's publication date, a list of official holidays, or the expiration date for an offer (if not tied explicitly to a time zone).
> Example 4:
> Suppose that your application delivers newspapers to users. Your application wants to show the publication date of each issue so that, for example, The Sunday News is always shown as being published on a Sunday. The publication date is thus a "floating time" value.
>
]FIG]
[FIG(quote)[
[FIGCAPTION[
[5] [CITE@en-US[Working with Time Zones]]
( ([TIME[2011-07-05 21:14:06 +09:00]]))
<https://www.w3.org/TR/timezone/#guidelinessummary>
]FIGCAPTION]
> When comparing times, floating times with no time zone information should use UTC as the time zone.
]FIG]
[FIG(quote)[
[FIGCAPTION[
[6] [CITE@en[RFC 5545 - Internet Calendaring and Scheduling Core Object Specification (iCalendar)]]
( ([TIME[2016-06-05 16:19:53 +09:00]]))
<https://tools.ietf.org/html/rfc5545#section-3.3.5>
]FIGCAPTION]
> FORM #1: DATE WITH LOCAL TIME
> The date with local time form is simply a DATE-TIME value that
> does not contain the UTC designator nor does it reference a time
> zone. For example, the following represents January 18, 1998, at
> 11 PM:
> 19980118T230000
> DATE-TIME values of this type are said to be "floating" and are
> not bound to any time zone in particular. They are used to
> represent the same hour, minute, and second value regardless of
> which time zone is currently being observed. For example, an
> event can be defined that indicates that an individual will be
> busy from 11:00 AM to 1:00 PM every day, no matter which time zone
> the person is in. In these cases, a local time can be specified.
> The recipient of an iCalendar object with a property value
> consisting of a local time, without any relative time zone
> information, SHOULD interpret the value as being fixed to whatever
> time zone the "ATTENDEE" is in at any given moment. This means
> that two "Attendees", in different time zones, receiving the same
> event definition as a floating time, may be participating in the
> event at different actual times. Floating time SHOULD only be
> used where that is the reasonable behavior.
> In most cases, a fixed time is desired. To properly communicate a
> fixed time in a property value, either UTC time or local time with
> time zone reference MUST be specified.
> The use of local time in a DATE-TIME value without the "TZID"
> property parameter is to be interpreted as floating time,
> regardless of the existence of "VTIMEZONE" calendar components in
> the iCalendar object.
]FIG]
[7] [CODE(HTML)@en[<input type=datetime-local>]] が扱うのも[[浮動時]]です。
[CODE(JS)@en[Date]] への変換では、 [[UTC]] とみなされた値になります。
[8] [CITE@ja['''['''perl''']'''DateTimeのtimezoneについてのメモ - $shibayu36->blog;]]
( ([TIME[2016-06-15 13:01:25 +09:00]]))
<http://blog.shibayu36.org/entry/20111002/1317542196>