std-unix@ut-sally.UUCP (Moderator, John Quarterman) (01/19/86)
Date: Tue, 14 Jan 86 12:04:40 est
>From: seismo!cbpavo.cbosgd.ATT.UUCP!mark@sally.UTEXAS.EDU (Mark Horton)
In the context of standardizing the handling of time zones for UNIX,
the question has arisen: is a timezone offset in minutes good enough,
or does someone need to be able to say "We're at 2 hours, 14 minutes,
and 23 seconds east of GMT"?
I've noticed that most places in the world are on standard
time, and the offsets are either whole hours or half hours.
However, I understand that Saudi Arabia is on "solar time",
which I take it means that the time zone is based on the
exact position of the sun for each town. I also understand
that there may be other countries that don't use standard time.
I'd appreciate a note from anyone who is familiar with the time
zone customs of such countries. What I'd like to know is:
(1) Are offsets always to the nearest minute, or are they sometimes
done to the nearest second?
(2) Are any means taken to compensate for the fact that the Sun is
sometimes up to 8 minutes fast or slow? That is, does the clock run
faster or slower at certain times of the year?
(3) How accurate are times? In official places (such as telephone
companies, airports) that make real use of clocks, are clocks expected
to be correct right down to the second, or are errors of a minute or
so typical? (Even in the USA, people's wristwatches and wall clocks
are usually off by a few minutes, but computers can now synchronize
their clocks to WWV.)
(4) How important is the accuracy of the time? Is it a major religious
ritual to have the time accurate down to the millisecond, or does somebody
just set the clock from a sundial and hope it's within 10 minutes?
Thanks in advance for replies. I'll summarize later to mod.std.unix.
Mark Horton
Volume-Number: Volume 5, Number 19