tztab entries (forwarded with permission)

[Paul Eggert]

   Date: Wed, 13 Aug 1997 17:02:05 +0100 (BST)
   From: Dave Kelly <dkelly at lhr-sys.DHL.COM>

   Can you offer any guidelines on the allocation of canonical names to
   these futures?

For the names I mentioned (e.g. `Europe/Paris'), the guidelines are in
the `africa' file in the tz distribution.  Look for ``Here are the
general rules I used for choosing location names''.  This is an
admittedly an odd place for the guidelines; they should get moved
someday.

   "CST" is used in China/Australia/US.  What would you recommend as
   the most common set?

But now you seem to be asking about time zone abbreviations.  This is
a different issue.  If you're worried about these abbreviations, then
the list that I gave you is too small, and more work would have to be
done.

For example, computers in Singapore generally use the abbreviation
`SGT' for ``Singapore Time'', whereas those in China generally use
`CST' for ``China Standard Time''; but the list I sent you had just
one entry `Asia/Shanghai' that covers both locations, since they're
both 8 hours ahead of UTC all year.  The Asia/Shanghai entry also
covers many other locations that are always 8 hours ahead of UTC,
ranging from Asia/Ishigaki (which uses `CST') to Antarctica/Casey
(which uses `WST').

   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?

Yes.