What is a time zone?

[Gwillim Law]

Syed Sajjath wrote,
> > if an Australian user asks for 10:00 am EST, we know it is australian
time,
> > not US.  Whether it is Standart or Summer we calculate based on the
> > scheduled time(our assumption is user just wants the conference at that
> > local time).

Eric Ulevik replied,
> Of course, this isn't enough. Right now, in Sydney EST means Eastern
Summer
> Time and in Brisbane EST means Eastern Standard Time.

Syed responded,
> You are correct, we do offer two timezones EST(no daylight Savings) and
> EST(with daylight Saving) in Australia for the user to select.

How does the user know which one to select, if he or she isn't familiar with
Australian time zones?  Besides, Australian EST(with daylight Saving) in
Sydney is different from Australian EST(with daylight Saving) in Hobart.
Currently, daylight saving time begins on the first Sunday in October in
Hobart.  It begins on the last Sunday in October in Sydney.

Yours,    Gwillim Law