Need confirmation of "Posix time standard" on FreeBSD

Someone mentioned recently that a timezone style of "GMT+0800" was on
their FreeBSD machine as an allowed time zone, that its behavior was
the same as the usual ISO8601 timezone of "-0800", and that this
conformed to some sort of Posix standard.

I had posted patches for this, and have just modified the patch to be
cleaner and more robust.

Before committing this (or at least before completing our upcoming
beta period), I'd like confirmation that this actually matches
expected behavior for a machine implementing a "GMT+0800" (or similar)
time zone, and that it is indeed a Posix standard? Anyone??

- Thomas

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Thomas Lockhart lockhart(at)alumni(dot)caltech(dot)edu
South Pasadena, California