[Zope3-dev] Can we remove ZopeLegacy for now?

[Guido van Rossum]

[Guido]
> > So are April 6 and 7, US/Eastern, in the same timezone or not?

[Wade Leftwich]
> Is: If by "US/Eastern" you mean a jurisdiction that switches to DST during 
> the night of 4/6 - 4/7, NO. You go to bed in EST, and you wake up in EDT.

This is a good example of my confusion as to what people mean when
they say "timezone", which is why I want to avoid it like the plague
in the documentation and API for the implementation.  Is US/Eastern
the timezone, or are EST and EDT the timezones?  Or are they all three
timezones?  Or is EST/EDT one timezone?  And how does it differ from
US/Eastern?

IMO, EST and EDT are names for specific offsets from UTC (-5 and -4
hours, respectively).  This can be seen as a simple function from UTC
to local time (adding a fixed amount).

On the other hand, US/Eastern names a more complex function from UTC
to local time: this function sometimes subtracts 4 hours, and
sometimes subtracts 5 hours.  The transition points (the UTC values
where the offset changes) are also part of the function's definition.
Note that the exact behavior of the function in the distant future is
unknowable, and in the distant past it makes no sense, but for
argument's sake, it is nevertheless extended indefinitely in both
directions.

I'll reply about US/Indiana (which IMO is *not* a timezone in any
meaningful sense of the word) in a separate response to Tim.

--Guido van Rossum (home page: http://www.python.org/~guido/)