[tz] Posix time zone question

[Guy Harris]

On Jan 11, 2012, at 1:38 PM, Bennett Todd wrote:

> And notation like EST5EDT is the old format, prior to the zoneinfo database, and says it's GMT+5, with no provision for summer time;

Actually, that would be EST5; EST5EDT is GMT+5, with summer time, using some unspecified rules (in practice, whatever happened to be built into the C library; with the Olson code, it's whatever rules came from the "posixrules" file).