I recently designed a time zone converter and reference site using the excellent database that is maintained at this site. Conversions between time zones appear as expected except when the time zone involves one of the Etc/GMT+ or Etc/GMT- designations. To provide a specific example (and maintain my own sanity) assume the following time zones: GMT, Etc/GMT-5, and US/Central With DST currently in effect, US/Central is 5 hrs behind GMT. Therefore, GMT - US/Central = +5. However, the database indicates that GMT - 'Etc/GMT-5' = -5. Or, stated another way that GMT plus 5 hrs equals Etc/GMT-5 (?) Most people would associate GMT-5 with "the time zone which is 5 hrs behind GMT." However, the database seems to have this defined as "the time zone for which GMT is 5 hrs behind." Can someone confirm that the results I obtained are reproducible? Is there something I do not understand or are the definitions for the Etc/GMT+n and Etc/GMT-n designations reversed in the database? Thanks for your help. Rich Shockney Timezoneconverter.com
"Richard L. Shockney" wrote on 1999-06-09 17:42 UTC:
I recently designed a time zone converter and reference site using the excellent database that is maintained at this site. Conversions between time zones appear as expected except when the time zone involves one of the Etc/GMT+ or Etc/GMT- designations.
The sign of the Etc/GMT+-... files is as defined in POSIX.1 http://www.cl.cam.ac.uk/~mgk25/volatile/posix-1-8-1-1.pdf for the TZ environment variable, which many people consider to be counterintuitive and also incompatible to the ISO 8601 notation http://www.cl.cam.ac.uk/~mgk25/iso-time.html#zone Hope this helped Markus -- Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>
Thanks markus! As I suspected... Yuk! Rich -----Original Message----- From: Markus Kuhn [mailto:Markus.Kuhn@cl.cam.ac.uk] Sent: Wednesday, June 09, 1999 1:45 PM To: rshockney@ibm.net Cc: tz@elsie.nci.nih.gov Subject: Re: GMT Delta Confusion "Richard L. Shockney" wrote on 1999-06-09 17:42 UTC:
I recently designed a time zone converter and reference site using the excellent database that is maintained at this site. Conversions between time zones appear as expected except when the time zone involves one of the Etc/GMT+ or Etc/GMT- designations.
The sign of the Etc/GMT+-... files is as defined in POSIX.1 http://www.cl.cam.ac.uk/~mgk25/volatile/posix-1-8-1-1.pdf for the TZ environment variable, which many people consider to be counterintuitive and also incompatible to the ISO 8601 notation http://www.cl.cam.ac.uk/~mgk25/iso-time.html#zone Hope this helped Markus -- Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>
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Richard L. Shockney