bug#7997: Feature request for date command

[Richard Stallman]

    For date input (using --date=STRING) you can use the TZ variable to
    specify the input timezone.  Here is an example.

      $ date -R --date='TZ="Europe/Rome" 2004-10-31 06:30'
      Sat, 30 Oct 2004 23:30:00 -0600

      $ TZ="America/New_York" date -R --date='TZ="Europe/Paris" 2004-10-31 
06:30'
      Sun, 31 Oct 2004 01:30:00 -0400

That does the job, but it is not documented in the manual.
Could you document it, and add these examples?

-- 
Dr Richard Stallman
President, Free Software Foundation
51 Franklin St
Boston MA 02110
USA
www.fsf.org, www.gnu.org