FW: Question about: TWiki.org Service: Date and Time Gateway

Paul Eggert eggert at CS.UCLA.EDU
Mon Feb 14 23:36:04 UTC 2005

This confusion basically stems from twiki's adoption of the tz
convention, which in turn comes from POSIX, which in turn is backwards
from the normal.  I'll add something like the following text to
tz-link.htm.  I don't see any simple fix to the twiki.org page, other
than a footnote containing the following info (which would probably
cause more confusion than it'd cure).

<li>Numeric time zone abbreviations typically count hours east of
UTC, e.g., <code>+0900</code> for Japan and <code>-1000</code> for
Hawaii. However, the <abbr>POSIX</abbr> <code>TZ</code> environment
variable uses the reverse convention. For example, one might use
<code>TZ="JST-9"</code> and <code>TZ="HST10"</code> for Japan and
Hawaii, respectively. One should never set <code>TZ</code> to a
value like <code>"GMT+5"</code>, since this would mean local time
is five hours behind UTC and the time zone is called "GMT". If the
<code>tz</code> database is available, it is usually better to use
settings like <code>TZ="Asia/Tokyo"</code> and
<code>TZ="Pacific/Honolulu"</code> instead, as this should avoid
confusion, handle old timestamps better, and insulate you better from
any future changes to the rules.</li>

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