GMT Delta Confusion

Richard L. Shockney rshockney at
Wed Jun 9 17:42:08 UTC 1999

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

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