Question on 'date' command: why UTC_sign_number_ is inverted?

[Masataro Asai]

Hi, everyone.

I'm confused by the behavior in the `date` command.

>[guicho coreutils]$ TZ='Asia/Tokyo' src/date -R --date="2014/1/1"
>Wed, 01 Jan 2014 00:00:00 +0900
>[guicho coreutils]$ TZ='UTC+9' src/date -R --date="2014/1/1"
>Wed, 01 Jan 2014 00:00:00 -0900
>[guicho coreutils]$ TZ='America/Los_Angeles' src/date -R --date="2014/1/1"
>Wed, 01 Jan 2014 00:00:00 -0800
>[guicho coreutils]$ TZ='UTC-8' src/date -R --date="2014/1/1"
>Wed, 01 Jan 2014 00:00:00 +0800

Assuming that I live in Japan and I use JST (Japan Standard Time)
 which is identical to
(UTC+9)[http://en.wikipedia.org/wiki/Japan_Standard_Time],
this is not what I expected. The third and fourth case, in PST=US/LA,
seems odd as well.
Is this a bug or the intended behavior?
The machine is running on ubuntu linux 12.04 and I used the latest
master branch.

BTW, I found it while I was writing a script that helps me submitting my
paper in time,
which get the time in UTC-12.
Some of you may know, conference paper deadlines are sometimes defined
with UTC-12
so that: "If you are in time anywhere on the world, you are in time. "

-- 
Masataro Asai

Department of General Systems Studies
Graduate School of Arts and Sciences, The University of Tokyo

Tel: (81)-44-856-9009
Twitter/github id: guicho271828