Data::ICal::Entry::TimeZone::Daylight - Represents a Daylight Time base offset
from UTC for parent TimeZone
A time zone is unambiguously defined by the set of time measurement rules
determined by the governing body for a given geographic area. These rules
describe at a minimum the base offset from UTC for the time zone, often
referred to as the Standard Time offset. Many locations adjust their Standard
Time forward or backward by one hour, in order to accommodate seasonal changes
in number of daylight hours, often referred to as Daylight Saving Time. Some
locations adjust their time by a fraction of an hour. Standard Time is also
known as Winter Time. Daylight Saving Time is also known as Advanced Time,
Summer Time, or Legal Time in certain countries. The following table shows the
changes in time zone rules in effect for New York City starting from 1967.
Each line represents a description or rule for a particular observance.
Effective Observance Rule
Date (Date/Time) Offset Abbreviation
1967-* last Sun in Oct, 02:00 -0500 EST
1967-1973 last Sun in Apr, 02:00 -0400 EDT
1974-1974 Jan 6, 02:00 -0400 EDT
1975-1975 Feb 23, 02:00 -0400 EDT
1976-1986 last Sun in Apr, 02:00 -0400 EDT
1987-* first Sun in Apr, 02:00 -0400 EDT
Note: The specification of a global time zone registry is not addressed by this
document and is left for future study. However, implementers may find the
Olson time zone database [TZ] a useful reference. It is an informal,
public-domain collection of time zone information, which is currently being
maintained by volunteer Internet participants, and is used in several
operating systems. This database contains current and historical time zone
information for a wide variety of locations around the globe; it provides a
time zone identifier for every unique time zone rule set in actual use since
1970, with historical data going back to the introduction of standard time.
Returns "DAYLIGHT", its iCalendar entry name.
According to the iCalendar standard, the following properties must be specified
exactly one time in a daylight declaration:
dtstart tzoffsetto tzoffsetfrom
According to the iCalendar standard, the following properties may be specified
any number of times for a daylight declaration:
comment rdate rrule tzname
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