AT TIME ZONE and interval arguments

Hi all

I'm mildly thrown by this:

regress=> SELECT TIME '04:00' AT TIME ZONE '01:00';
  timezone
-------------
 19:00:00-01
(1 row)

regress=> SELECT TIME '04:00' AT TIME ZONE (INTERVAL '01:00');
  timezone
-------------
 21:00:00+01
(1 row)

regress=> SELECT TIME '04:00' AT TIME ZONE (TEXT '01:00');
  timezone
-------------
 19:00:00-01
(1 row)


and was wondering if anyone knows why the sense of the offset is
reversed for typed intervals vs bare literal or text. Is this another
one of the issues caused by the various standards' disagreements about +
vs - time offsets?

--
 Craig Ringer                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services