FW: tztab entries (forwarded with permission)

Dave Kelly dkelly at lhr-sys.DHL.COM
Wed Aug 13 16:02:05 UTC 1997


>From           : x>eggert at twinsun.com
To             : dkelly at lhr-sys.DHL.COM
Subject        : Re: FW: tztab entries (forwarded with permission)
CC             : tz at elsie.nci.nih.gov
Date           : 13/08/97 00:46


Hi Paul

Thanks for your help on this.

> Here's what I think you're asking for.  If you're interested only in
> times now and in the future, then the Olson database contains too many
> names, partly because it goes back to 1970 and thus must track
> historical changes, and partly because it insists on at least one name
> per country.  You want just one distinct name for each time zone
> future, regardless of country.

Yes, this is exactly what we need.

> This script assumes that the only thing that
> matters about a time zone is its UTC offset; it ignores the time zone
> name (e.g. "EST", "EDT") and whether the time is daylight-saving time.

Just to reassure me - I assume that futures with the same UTC offsets
but with different daylight savings time change dates are considered
to be distinct by the script?

Can you offer any guidelines on the allocation of canonical names to
these futures?  The tztab entry on HP-UX does seem to follow a
convention of <zone name><offset><dst zone name>, e.g.:

 GMT0BST, WET0WETDST, PST8PDT, CST-9:30CDT

but there appear to be different variations of these, e.g.  for
Central Europe I could use CET-2CEST or CET-2CETDST (and that's
without considering MEDST, MEST, MESZ, METDST).  Also "CST" is used
in China/Australia/US.  What would you recommend as the most common
set?

Thanks again for the help

Dave Kelly



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