NAME

       Data::ICal::Entry::TimeZone::Daylight - Represents a Daylight Time base offset from UTC
       for parent TimeZone

DESCRIPTION

       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.

METHODS

   ical_entry_type
       Returns "DAYLIGHT", its iCalendar entry name.

   mandatory_unique_properties
       According to the iCalendar standard, the following properties must be specified exactly
       one time in a daylight declaration:

               dtstart  tzoffsetto  tzoffsetfrom

   optional_repeatable_properties
       According to the iCalendar standard, the following properties may be specified any number
       of times for a daylight declaration:

               comment  rdate  rrule  tzname

AUTHOR

       Jesse Vincent "<jesse@bestpractical.com>" with David Glasser, Simon Wistow, and Alex
       Vandiver

LICENCE AND COPYRIGHT

       Copyright (c) 2005 - 2009, Best Practical Solutions, LLC.  All rights reserved.

       This module is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself. See perlartistic.

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