First off. In general icalendar files are required to include the
definitions of any time zone ids they reference in the form of a
BEGIN:VTIMEZONE block.
Neither the old or new icalendar RFCs define standard time zones.
Rical allows processing of calendars which don't by using either the
TZInfo gem which is a wrapper for the tz database (commonly referred
to as the Olson database) or the equivalent implementation of tzinfo
in activesupport.
Now the problem is that EDT, despite what your dad might have told you
is not a timezone, in the context of the timezone used in the eastern
US, it's the name of a period during which the local time has a
particular offset from UTC. I'm pretty sure that it's also ambiguous
since other time zones may also use the abbreviation EDT to name a
period.
A time zone, is a geographical region which agrees about the times
when the UTC offset changes back and forth between daylight saving (or
summer time) and standard time. In general the Olson database uses a
combination of a large region, and a prominent city. So what you are
probably looking for is America/New_York
http://en.wikipedia.org/wiki/Zoneinfo#Definition_of_a_time_zone
--
Rick DeNatale
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