How to get the time zone offset using to_char

I need to convert timestamp to a format with a time zone offset, like this:

select clock_timestamp()::text;

which returns:

"2011-12-30 11:59:06.538+01"

What is the default format for timestamp::text conversion? I've tried this:

select to_char(clock_timestamp(), 'YYYY-MM-DD HH24:MI:SSTZ');

But it gives me "CET" instead of "+01":

"2011-12-30 11:59:06CET"

--
Cezariusz Marek http://midicat.net/