Calendar Types

Glynn Clements glynn at
Mon Feb 14 15:46:36 EST 2005

Bayley, Alistair wrote:

> > From: Ashley Yakeley [mailto:ashley at] 
> > 
> > * Should we include a timezone field in CalendarTime?


> Should it include the timezone name? Although the name determines the
> offset, a given offset could match many names, so to preserve information
> we'd probably want to retain the timezone name internally. Do we want to
> support timezone names?

Yes. A timezone name incorporates DST behaviour, i.e. it specifies
different offsets at different times of the year.

> Do we want to embed summer-time (daylight-savings) timezone behaviour into
> the library? This would obviously be useful for displaying the correct local
> time, but makes the timezone part of the library quite complex.

Yes. The library wouldn't be much practical use without it.

I'm aware that this results in ill-specified behaviour. E.g. if the
DST dates are changed (as happens occasionally), calculations
involving future dates will vary depending upon whether the system's
timezone database has been updated.

Glynn Clements <glynn at>

More information about the Libraries mailing list