[ntp:questions] Re: Problems with the Timezone

David Woolley david at djwhome.demon.co.uk
Thu May 11 21:13:33 UTC 2006

In article <1147351652.229009.51090 at j73g2000cwa.googlegroups.com>,
Marvin Garcia <marvingm at gmail.com> wrote:

> But what i dont get is why with a local reference clock i always used
> GMT-4 in solaris and even in windows has always work fine with GMT-4.
> But now that we decided to change to a external reference clock the
> timezone have to change. that's what i dont now why?

Probably because your machine's time was completely broken before but 
you never noticed, because you never had something with a correct 
timestamp.  GMT-4 is doubly broken; GMT is only suitable for zero 
offsets, and because the sign is wrong.

Old style Unix time zone codes almost certainly use positive numbers for
the USA because Bell Labs was in the USA.  On the other hand, the proper
international standard uses negative numbers for the USA.

Also, the old style timezone codes DO NOT contain the string GMT, unless
the standard time is GMT.  GMT is ALWAYS followed by 0.

Examining the (rather dated) Olsen timezone data that I have, you are
fortunate that you haven't used daylight saving time since January 1974
(although there was a time in Autumn 2000 when you were on the +0500
timezone).  That means one doesn't have to worry about simple timezone
codes assuming obsolete US legislation.

Your correct, old style, Unix timezone code is AST4, assuming that there
have been no more glitches since 2000-12-03T06:00:00Z.   AST4 should work
on even the oldest of Unices.  America/Santo_Domingo only works on those
that have the Olsen package (e.g. not on standard SCO Openserver).

PS  Could you please not post three copies of everything; it makes a
mess of threading.

PPS, for the person who said that XXX9 is a name.  It's not.  It's 
a code that is interpreted by the time libraries.  E.g. XXX9 is 
completely fictious, but still works:

$ date -u
Thu May 11 21:11:46 UTC 2006
$ TZ=XXX9 date
Thu May 11 12:11:56 XXX 2006

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